Retention , Relapse and Stability in Orthodontics

1. 1 Retention Retention Relapse Relapse Stability Stability Prepared by: Prepared by: Dr. Mohammed Alruby Dr. Mohammed Alruby Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 Retention Definition: = it’s an attempts of biological and mechanical preservation of tooth and dental arches in their new position obtained by active orthodontic treatment. =It is a continuation of treatment. =Or it maintaining newly moved tooth position long enough to aid in stabilizing their correction. Why retention is necessary: Orthodontic results are potentially unstable; the teeth have a tendency to move in the direction of original malocclusion after removal of active appliances. Therefore, retention is necessary for the following reasons: The gingival and periodontal tissues are affected by the teeth movement and require a time for reorganization after appliance removal. The orofacial musculatures are stretched and require time for adaptation to the new position. The growth changes may alter the orthodontic treatment results, so that the retention should not discontinued until growth is mostly completed in most cases. Retention should be considered as a part of orthodontic treatment, and should be applied until all the tissues in the system: teeth, - alveolar bone, - jaw bone, - muscles, - become in a state of balance both structurally and functionally to meet a new requirement The concept and reasons of retention are given by (Angle1972) as: {after the malposed teeth have been moved into the desired position, they must be mechanically supported until all the tissues involved in their support and maintenance become modified in both structure and function to meet the new requirements} History and schools of retention: The occlusion school (1880): According to Kingsly, the occlusion of the teeth is the most potent factor in determining the stability of the teeth moved to new position. The musculature school: According to Rogers 1951, functional muscle balance that maintains the dentition in stable position is an important factor in retention. There should be balance between the outer buccal envelop and inner group of muscles such as tongue musculatures. The mandibular incisors school: According to Grieves (1944) and Tweed (1954) the angulation of mandibular incisors is an important factor in retention, post treatment stability is increased when the mandibular incisors were slightly retroclined or placed ideally in upright position over the basal bone. The apical base school: =Alex lundstom 1925 suggested that the apical base (the area between the alveolar bone and the basal bone), was one of the most important factors in the correction of malocclusion and maintenance of corrected occlusion. =McCauly 1944 suggested that inter-canine width and inter-molar widths should be maintained as originally presented to minimize retention problems. =Nance noted that arch length may be permanently increased only to limited extent Theories of retention: Riedel has been listed a nine theories that explaining retention, the tenth theory was added by Moyers as an extension to the existing theories. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 Theorem 1: = The teeth that have been moved tend to return to their former position. =This particularly true for rotation than any other tooth movement, and for anterior teeth than posterior teeth which have a firm occlusion. Theorem 2: =Elimination of the causes of malocclusion will prevent recurrence. =Many causes of the malocclusion are not known, failure to remove the etiological factors may be lead to relapse. =The importance of this factors can be seen in malocclusion associated with abnormal habits such as thumb sucking tongue thrust, etc. Theorem 3: =Malocclusion should be over corrected as a safety measure. This concept has been practiced in treating certain malocclusion such as rotation, deep bite, class II and Class III. =Solzman found no advantage obtained by over correction of buccal segment, furthermore over correction can initiate traumatic occlusion. Theorem 4: =Proper occlusion is a potent factor in holding the teeth in their corrected position. =Angel 1907 believed that, the stability of orthodontic results could be achieved by creating normal occlusion he stated that (nature always starts out to build a perfect denture in each person). = Moyers found that, the occlusal positions that obtained by orthodontic treatment should be coincide with the unconscious reflex swallowing position which is very important factor in stabilization of the corrected occlusion. Theorem 5: Bone and soft tissues should be allowed an enough time to reorganize around the newly positioned teeth. This theory is the base for using of retainer after active orthodontic treatment. It takes a considerable time for the reorganization of bone and collagen fibers of periodontal ligament and gingiva. Theorem 6: If the lower incisors are placed in an upright position over the basal bone, they are more likely to remain in good alignment. Up-righting means that, lower incisors are perpendicular to mandibular plane plus or minus 5 degrees, this too difficult to be applied in cases with sever anteroposterior discrepancies. Theorem 7: correction carried out during periods of growth are less likely to relapse. This due to the greater adaptability of the orofacial structures during these period, retention should be maintained till active growth phase is over. Theorem 8: The farther the teeth have been moved, the lesser is the risk of relapse. This theory is strange in logic and there is no evidence to support it. Theorem 9: Arch form, particularly the mandibular arch, cannot be permanently altered by the appliance therapy. This is particularly true for cases treated with fixed appliance after growth is over, while treatment in mixed dentition with bite plates, extra-oral or functional appliances may provide some natural widening of the mandibular arch diameter. So that, treatment should be directed toward maintaining the arch form. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 Theorem 10: Moyer theorem: This theorem is added by Moyers which stated that, many treated malocclusion require permanent retention. Graber pointed out that, the retaining of teeth in an abnormal position by permanent retainers can causes permanent damage to both teeth and supporting tissue as they attempt to hold them against the functional forces, so permanent retention is an unhealthy condition. Keys to eliminate the lower retention: Williams and Raleigh (1985) put 6 keys to eliminate the lower retention and achieve lower arch stability after orthodontic treatment: The incisal edge of the lower incisors should be placed on A-pog line or 1mm in front of it and this give a good soft tissue balance. The apices of the lower incisors should be spread distally to the crown, lateral incisors spread more distal than the central incisors. The apex of lower cuspid should be positioned distal to the crown. When viewed in lateral radiograph all four lower incisor apices must be at the same labiolingual plane. Lower cuspid root apex must be positioned slightly buccal to the crown apex. Flattening of lower contact points prevent their slippage. NB: Centroid theory: according to Huston (1989) the incisal edge of lower incisors should be anterior to the centroid of the roots of upper central incisors. Factors to considered in planning retention phase of treatment: Periodontal force: =Widening of the periodontal space and disruption of the collagen fibers supporting the teeth are the normal response to orthodontic tooth movement, even if the tooth stops before appliance removal, reorganization of periodontal tissue will not occur as long as the teeth are splinted together with rigid arch wires, so that holding the teeth with passive arch wires cannot be considered the beginning of retention. =Once the appliance is removed each tooth can respond individually to occlusal stress, reorganization will take place within 3 to 4 months and the slight mobility present at appliance removal disappear. The teeth normally withstand occlusal force because of the shock absorbing properties of the periodontal system. =the gingival fibers are composed of elastic and collagen fibers, both reorganize more slowly than the other group of periodontal fiber. Collagen gingival fibers remodel within 4 to 6 months, while elastic supracrestal fibers remodel very slowly, and can exert displacing force upon the teeth approximately for one year after appliance removal, for this reason some author recommended Supracrestal fibrotomy before or just after appliance removal in cases of sever rotations. =Reitan: in his microscopic studies of post retention changes (1959, 1966, 1967) found that supracrestal gingival fibers appear histologically altered and directly deviated after rotational movement, and this condition did not lessen even after years of retention. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 =Parker: in clinical study of trans septal fibers (1972) stated that, rotational relapse is a normal response to an abnormal force, the paralleling of the teeth roots, sectioning of free gingival fibers, and elongation o retention period are very important in stability aft rated cases. =Kaplan: 1967: in national survey on the extent of fibrotomy, concluded that, while the surgical technique is not widely prescribed, it seems problem free and its use will be increasing in the future. Muscle force: Normal function and balance of orofacial musculatures are very important factors in facial balance and occlusal stability after orthodontic treatment. Moyers (1965): study the effect of muscle activity on retention, he stated that, failure to deal with any one or all of the functional problems can lead to relapse. He further emphasized that, if the results to be stable the treated or new occlusion must be in harmony with muscular pattern. Tweed: said that abnormal muscle function is a major factor in relapse. The muscle effect is of great importance after inter-maxillary correction than intra-maxillary correction as in intra- maxillary the muscles will be stretched behind their normal resting position as a result of new jaw relation. In such cases the retention should be for long periods until the muscles accommodate themselves to the new position and re-stablish their lost balance. The early treatment during active growth period is advantageous because the muscles are still actively growing, their origin and insertion are changeable and can easily move in the direction that favorable to achieve. Rogers (1953-1951): introduce a consideration of necessity to establish proper muscle function and balance after orthodontic treatment. He introduces an exercise training program for proper strengthening of the muscles of mastication and facial muscles to aid in treatment as well as retention. Change in masticatory function brought about by change in dental occlusion require time for their establishment. Clinical consideration: muscle aberration should be expected in the following: Class II and III muscular malocclusion. Skeletal deep bite and skeletal open bite. Persistence of abnormal pressure habits. Over expansion of posterior teeth and procumbancy of anterior teeth. Growth changes: Residual growth is troublesome particularly in patients whose initial malocclusion is due to abnormal growth pattern. Comprehensive orthodontic treatment usually starts in the early permanent dentition (12years) and take about 18 to 30 months, so it ends at 14 to 15 years but the growth may continue till 20 years. Furthermore, the long term growth studies have indicated that, growth takes place at very slow rate during adult life. It was found that, various facial types have different term of growth and treatment response, as: Patients with long face syndrome express more backward mandibular rotation which result in relapse of corrected open bite deterioration of class II treatment results. Patients with short face express more forward mandibular rotation which can influence the potential for deepening the bite and contribute to mandibular incisor crowding. Zaher A, and his colleagues concluded that the facial types does not play a significant role in stability of orthodontic treatment results. It extremely important to pay attention to the person’s growth pattern which should be individualized and not based upon statistics obtained from growth studies in general population, so that each patient has its own growth pattern that should be taken into consideration. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

6. 6 Timing of pubertal growth spurt: Nanda and Nanda, found that, the pubertal growth spurts for patients with skeletal deep bite occur in average 1.5 to 2 years later than the case of open bite so, longer retention period for the skeletal deep bite Age of patients: Early treatment is advantageous for both ease of treatment and stability results due to higher adaptability of dento-facial structures to the new situation, in addition to the higher rate of turnover of bone and periodontal tissue. Sex: Girls mature earlier than boys so that retention is expected to be longer in boys than in girls. Type of treatment: =little et al studied 65 premolar extraction cases for at least 10 years post retention, they report mandibular arch shortening was seen in 63 cases and post treatment crowding that not associated with the degree of arch inter canine width changes during treatment. Kinne: examined 55 patients at least 10 years after serial extraction and showing post treatment irregularity. Elms et al: studied a sample of patients with class II division 1 malocclusion who treated without extraction and with headgear and fixed appliance after 6.5 years post retention and they found 90% irregularities. They concluded that the factors that responsible for the stability seen: The application of proper mechanics. Cooperation of patients. Favorable downward and forward mandibular growth. Nieke et al: found more significant relapse of crowding and rotation in extraction case than non- extraction cases. Length of treatment: The more rapid the treatment, the higher the tendency to relapse Mershon: pointed out that, the orthodontic treatment should be carried out in a phases, period of active treatment followed by period of rest. He stated that if the tissue permitted to adjust themselves through functional adaptation during the rest periods, no form of mechanical retention will be required. Presence of third molars: Late lower arch crowding was found to be influenced by the presence of 3rd molars. Broadbent: was an early advocated of insignificant role played by third molars in lower incisors crowding either impacted, erupted, missing or extracted. Niek et al; make a comparison between groups of bilateral erupted or impacted 3rd molars and agenesis or extraction revealed no significant difference in post retention changes. Ades et al; studied groups include absent, present, aligned or extracted 3rd molars, the results showing that no significant differences between these groups either in lower labial segment crowding or in growth pattern. Alteration of arch form: It is generally agreed that arch form and width should maintained during orthodontic treatment. Mills; =found stability after proclination in cases with skeletal deep bite and retroclined incisors. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

7. 7 = inter-canine and inter-molar widths decrease during post retention period, especially if there is expansion during treatment, so maintenance of arch form rather than arch development is generally recommended. =expansion is thought to be better tolerated in class II division 2 cases that show a significant greater stability to maintain inter-canine expansion than class I and II division 1 cases. Type of initial malocclusion, pre-treatment: The needs and duration of retention may differ according to the type of initial malocclusion as follow: A= cases requiring minimum or no retention appliance as: Blocked out canine in class I extraction cases with no incisor crowding. Class I anterior and posterior cross bite with very steep cusps and no anterior crowding. Teeth that have been treated with serial extraction. B= routine cases, extraction or non-extraction should have retaining appliance fixed or removable, at least until eruption of 3rd molars. C= cases that will need indefinite retention: Class II div. 2 deep bite. Expansion treatment. Patients with uncontrolled tongue or muscular habit. D= cases require an operative procedure with indefinite retention: Large maxillary teeth which may result in increased over bite or super class I will need stripping and canine to canine bonded palatal arch. Larger mandibular teeth which may result an edge to edge bite and spacing of maxillary incisors will require stripping and permanent bonded lingual retainer. Lack of incisal stop for any reasons will lead to deepening of over bite unless permanently retained. Also the type of retention is influenced by the type of original malocclusion: Retention after class II correction: Relapse toward a class II relationship must result from some combination of teeth movement (forward of upper arch and backward in lower arch) so: Over correction of occlusal relationship as a finishing procedure is an important step in controlling tooth movement, that would lead to class II relapse. Avoid much procumbency of lower incisors as a general guide line, if the lower incisors moved forward more than 2 mm relapse will occur by the pressure of lower lip unless permanent retention is applied. If maxillary growth has been restrained by either extra oral force or functional appliances, forward growth of maxilla is expected to occur after stopping of active treatment. Part time headgear should be used in conjunction with retainer to preserve the obtained results. If the patient is uncooperative, the alternative is to use functional appliances as a retainer to be worn on a part time basis in conjunction with day time retainer with conventional type. Retention should be between 12 to 24 months. Retention after class III correction: For class III the following must be considered: Over correction of over jet as a safety measures. The protraction appliances should be worn at least 3 to 6 months after active treatment as a part time. The chin cup should be worn part time until mandibular growth mostly completed. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

8. 8 Frankel 3 or reversed activators should be used as active retainer and at the same time patient should observed periodically until growth completed. Retention after deep bite treatment: Correcting of excessive deep bite is an almost routine part of orthodontic treatment, so wear a potential bite plane into the retainer which the lower incisors will contact to it because of vertical growth is continue to late teens. Retention after open bite: Relapse can occur by any combination of intrusion of incisors or extrusion of posterior teeth; the most important aspects are: Control the habits like thumb sucking or tongue thrust. Prevent extrusion of posterior teeth particularly the upper molars. High pull headgear in conjunction with upper and lower conventional retainer for day wear are effective in preventing relapse. Other alternative is to use open bite activator for night wear and conventional retainer for day wear from the beginning of retention period. Retention after incisors alignment: if the mandible grows forward or rotate downward, the effect carries the lower incisors into the lip which create force that =maxillary and mandibular incisors must be present in proper incisal stops. =a retainer in lower incisor region is needed to prevent crowding from developing until growth has declined to adult level. =Reidal 1992, stated that, incisor extraction may give greater stability at this area in absence of permanent retention. =Valinot, stated that, incisor extraction cases seem to exhibit less post retention recrowding. This may be due to the maintenance of these teeth near to their original position where muscle pressure is less likely to induce instability. Retention after correction of rotation: There is a high risk of relapse seen after rotation type of tooth movement due to resiliency of gingival fibers, so the following should be do: Long term retention. Circumferential supracrestal fibrotomy to prevent relapse. Retention after midline diastema: A removable simple Hawley’s retainer or bonded fixed bonded retainer from canine to canine on palatal side. Retention after cleft palate cases: Should be of longer duration than the normally used in non-cleft patients and sometimes it may necessary to maintain for a life time. Tissue reaction during retention period (post treatment tissue reaction) Fibrous tissues: Rearrangement of the fibrous tissues means that, the periodontal fiber bundles are again running more or less perpendicular to the root surface. Marginal area: The fibrous components of the marginal region are the transseptal and free gingival fibers. = Retain found that, after 28 days some rearrangement was observed on mesial and distal sides of the root. = The free gingival and transseptal fibers attached to the labial and lingual aspects of the root were still under tension after retention period of 232 days. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

9. 9 = Retain, Parker, and others, demonstrate oxytalan fibers in the periodontium of orthodontically treated teeth. These fibers increase in the area of stress which indicate that the oxytalan fibers is produced by the body as a safe guard against abnormal forces causing separation and destruction of the tissues. These fibers appear originated from soft tissue and inserted into cementum just apical to the transseptal collagen fibers. Middle area: The periodontal fibers in the middle area of the root rearranged in more perpendicular orientation to the root surface after 147-232 days. Apical area: The rearrangement was similar to that of middle region. NB: the exact mechanism by which the periodontal fibers reorganized and rearranged is still not fully understood, however several theories explain this process. Intermediate plexus: Sicher referred to the existence of intermediate plexus that, = Dissolute the fibrous connection = production of new fiber. = formation of new fibrous connection that adapt to the new situation This theory could not be demonstrating histologically in most experimental studies. Slippage theory: Postulated by Orban, which the reorientation of the existing collagen bundles occurs by slippage of some collagen fibers from the parent fiber bundle to join with other adjacent fiber bundle and thus involved in its lengthening. Osseous tissue remodeling: The periodontal fibers adapt to the new teeth positions by progressive osteogenic and cementogenic activities that ply an important role in shortening the extended fibers and reattachment of new fibers developing during teeth movement. The alveolar bone: = In all regions, the alveolar bone showed a very little rearrangement after 15 days = partial re arrangement occur after 28 days which the new bone formed as a tongue like spicules surrounded the stretched fiber bundle then laid down to fill the spaces among the primary bony spicules. = complete reorganization of alveolar bone and formation of mature bone occur after 147-232 days. Cementum: Root resorption is commonly associated with certain types of tooth movement, as expansion intrusion torque moving the root against the more-dense labial or buccal cortex. = Shallow resorbed area of the root may be repaired during retention period by new cellular cementum. = Extensive resorption of the root is questionable for repair. Orofacial musculatures: = Moyers 1960, studied the effect of muscle activity on retention and stated that, “failure to deal with any one or all of the functional problems can lead to relapse”. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

10. 10 = Tweed said that, “abnormal muscle function is the major factor in relapse, although I do not know how much one could change muscle function as a result of orthodontic therapy, I would try to overcome the preserve muscle and tongue habits. After inter-maxillary correction retention requires longer period until the muscles adapt themselves to the new position and re-stablish their lost balance. = Rogers 1935-1951 introduced an exercise training program for proper activation of muscles of mastication and orofacial muscles to aid in treatment as well as retention, however, his efforts not always crowned with success because some children were uncooperative. Clinical considerations: The Supracrestal fibers still represent a great problem during retention, these fibers are of special importance in certain tooth movement particularly rotation and closure of extraction site. Rotations: A number of clinical measures are introduced to prevent relapse tendency of rotated tooth: Retain stated that rotation should be corrected as early as possible before complete apical closure. This permit the root apex to close to close after the tooth moved to the new position with formation of new apical fibers that aid to stabilize the tooth to the new position. Rotation should be over corrected as a safety measure. Occlusal equilibration should be performed immediately before retention to give firm occlusion. Rotation should be corrected early in the course of treatment to permit longer period of fixation before turning to retention phase. Retainer should be inserted immediately after removal of active appliances. Parker among others stated that 50% of total relapse occurs during first 12 hours. Corrected rotation should be retained for longer periods, fixed retainer is preferred. Using surgical techniques as: Skosporg in 1927 introduced the technique of Septotomy that based on the tension theory of Walkoff. He believed that remaining tension in the bone tissue after phenomena of resorption and deposition was the major cause of orthodontic relapse, so the septotomy was designed to relief this tension. This technique consists of vertical sectioning of buccal and lingual cortex between the teeth from the level parallel to the root apex until the alveolar crest. Thompson in 1959 demonstrate that the apparent success of this technique not due to bone removal but due to severing the transseptal fibers. Immediate torsion: Hallett in 1956, de-rotate the tooth by surgical forceps and immobilized with fixed splints. He believed, that, this method severs the transseptal fibers that regenerate and adapt to the new position, but this method has a greater risk to pulpal degeneration and does not appear to reduce relapse significantly. Kole surgically removed the labial and lingual cortical plates prior to tooth movement. Brauer and tsopel transecting the Supracrestal fibers in mesial and distal direction with vertical incision. Radical gingivectomy introduced by Thopmson by removing all the attached gingiva around the rotated tooth, reduce the amount of relapse after initial retention period of 4 – 8 weeks. Edward transecting the Supracrestal fibers all around the tooth (circumferential fibrotomy) by using No 11 surgical blade to cut all the free gingival fibers to a depth of 3 mm. and below the alveolar crest. This procedure was performed immediately after 8 weeks of mechanical retention and no further retention was needed. Application of soft laser: Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

11. 11 Some studies as El-Namarawy and Eid used soft laser during retention period, they found that it redused the amount of relapse from 100% in control teeth to 43.6% in test teeth. Closure of extraction space: When the tooth is extracted, the transseptal fibers at the extraction site are severed, when the wound heals a newly formed transseptal fibers appears and capping the extraction site. As extraction space is closed orthodontically the new transseptal fibers coiled and compressed between the approximating teeth which cause: = resorption of the alveolar crest which does not re-generate again. = compression force re-open the extraction space again. Erickson and co-workers, concluded that, “it is biologically unsound to expect good proximal contact in areas where dental units have been removed and teeth approximated”. Burket, commented “the transseptal fibers remained in a coil fashion after extraction to such a degree that contact is impossible. Parker concluded that, the key of success in treated cases are: Paralleling of the teeth roots. Transection of transseptal fibers. Adequate time of mechanical retention. NB: on tension side, mesial to the tooth retracted, the transseptal fibers elongated rapidly and become stretched, further retraction lead to cutting of fibers or distal migration of tooth medial to active one, so (incisors should tie together with figure 8 ligature wire during canine retraction. NB: factors affecting retention: Factors enhancing retention: Achievement of proper occlusion: =proper inter-cuspation =proper axial inclination. =normal proximal contact. =normal overjet and overbite. =proper alignment of teeth. =flat occlusal plane. =proper and early correction of rotation. =absence of premature contact. Removal of causative factors. Proper muscle function. Proper knowledge about growth. Good general and oral health. Post treatment follow up until growth ceased. Factors interfering with retention: are the same that causing relapse. Failure to place the teeth in proper occlusion. Failure to remove the causative factors. Improper muscle function or failure to adapt the muscle to the new situation. Persistent pressure habits. Low rate of periodontal ligament turnover. Large size of tongue. Over expanded dental arch. Improper planning retention. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

12. 12 Lack of clinical experience and basic knowledge. Factors influencing the length and type of retention: Age of patient. Type of orthodontic correction. Degree and number of rotation. Health of oral tissues. The distance that the teeth moved. Retention period: Retention is needed for all patients wear orthodontic appliances, it should be: Essential full time wear for at least 5 months, except during eating (some cases need permanent splinting) Continued as part time wear for at least 12 months to allow time for remodeling of gingival tissues. If significant growth remains, continued as part time use until completion of growth. For practical purpose: all patients treated in early permanent dentition will require retention of incisor alignment until late teens. In those patients with skeletal disproportion initially part time of functional appliances or extra- oral force will be needed. # Some authors divide the retention into 2 phases = healing phase for 12 months to allow stabilizing of the teeth to the newly position. = maintenance phase to guard against the maturational changes in tooth position and need long time. NB: as a general rule retention at least should be equal to the treatment period. Clinical application of retention: Retention planning is divided into three categories depending on the type of treatment: Limited retention. Moderate retention in terms of both time and appliance wear. Permanent or semi-permanent retention. Limited retention: =corrected cross-bites: Anterior: when adequate overbite has been established. Posterior: when axial inclination of posterior teeth is good and patient having steep cusps. An exception is posterior cross-bites treated with either orthopedic or surgical expansion of mid palatal suture which need over correction and longtime retention. =dentition that has been treated with serial extraction: The percentage of complete satisfaction secondary to extraction depend on the degree of perfection desired by orthodontist. Extraction of 2nd premolars give more satisfactory results than extraction of 1st premolars. =high canine extraction case. =corrections that have been achieved by retardation of maxillary growth after the patient is through growing. =dentition in which teeth are separated to allow eruption of teeth previously blocked out, as partially impacted lower 2nd premolars and maxillary canines. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

13. 13 II- Moderate retention required: A = Class I non extraction cases characterized by protrusion and spacing of maxillary incisors these cases require retention until normal lip and tongue function has been achieved. B = class I or II extraction cases until lip and tongue function can achieved a satisfactory balance. It is generally desirable to use a maxillary Hawley retainer until normal functional adaptation occur. Sometimes desirable to use either maxillary headgear whose force is directed to permanent fist molars, or labio-buccal type of retainer with cervical or occipital resistance at night. The time for this type is reduced as patient adapt to new tooth position, proceeding from full time wear to once or twice each week. C =corrected deep overbite in either class I or II which require retention in vertical plane. =Anterior teeth depressed to achieve overbite correction then maxillary bite plane on retainer to allow prevention of relapse. =overbite correction is achieved as a result of mandibular clock wise rotation; vertical dimension should be held at least until growth of mandibular ramus height catches up. {NB: sever occlusal plane tipping also may require extended retention protocols and possibly additional maxillary restraint as well.} D= early correction of rotated teeth to their normal position: Before root formation has been completed. In mandibular incisor area, fixed lingual retainer or removable one with labial bow is probably best. Early correction of rotation, transeptal fibrotomy and long term fixed retention may be proving to be most satisfactory. E= cases involving ectopic eruption of teeth or presence of supernumerary teeth require varying retention time usually prolonged and occasionally a fixed or permanent retentive device such as bonded lingual retainer. Excessive spacing between maxillary incisors require prolonged retention after space closure. Supernumerary teeth may be encountered in the maxillary anterior area and on the removal of these teeth the maxillary teeth erupt slowly and incompletely. F= the corrected Class II div. 2 malocclusion generally requires extended retention to allow the adaptation of musculatures. These cases may have some increase in mandibular inter canine width and present of malalignment incisors, which needs to be maintained during retention. III- permanent or semi-permanent retention: Cases in which expansion has been the choice of treatment particularly in mandibular arch, may require permanent or semi-permanent retention to maintain normal contact alignment. Cases with considerable or generalized spacing may require permanent retention after space closure has been completed. Cases of sever rotations, particularly in adults or sever labiolingual malposition may require permanent retention as bonded lingual retainer. Spacing between maxillary central incisors. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

14. 14 Methods of retention: Functional: =Rogers and others have been stressed for the value of muscle exercise in maintaining the tooth position, particularly lip exercise. =activator may be used as a functional retainer, it can maintain teeth position and dental arch relationship. Natural: In which the proper inter-cuspation and proper incisor relationship will prevent relapse as corrected cross-bite. Appliances: Removable and fixed retainers. Requirement of ideal retainer: Should be restrain each tooth in desired position against the direction of relapse movements. Should permit the functional forces to acts freely upon the retained teeth permitting them to respond in physiologic manner as possible. It should be easily constructed and tolerated by the patient. It should be strong enough to achieve objective over the required period of use. It should be self-cleansing and can provide a good oral hygiene. It should be esthetically pleasant Removable retentive appliances: Advantages: Permit normal function of the teeth and investing tissues. It is a rigid fixation so allow some root movement, so that, the teeth can respond physiologically to the functional forces. Allow the periodontal ligament to rearrange themselves. It is easily fabricated and non-expensive. It is more hygienic. Disadvantages: Problems of patient cooperation. Hawley’s retainer: Designed by Charles Hawley in 1920, it is one of the most commonly used retainer, it can bring minor tooth movement by activating the labial bow. Components: Adams clasp. Short passive labial arch. Acrylic base material. = an acrylic plate to fit the palate, it should be festooned to fit the cervical contour of teeth. = two Adams clasp om molars or premolars. = a variety of labial bows can be used, as short labial, long labial, high labial bow. = the acrylic plate prevents palatal movement of the teeth, Advantages: Easy to fabricate because it is simple design. Good patient acceptance due to reduced bulk. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

15. 15 Can used in maxillary and mandibular arches. Its acrylic component offers bite plane to control deep over bite cases. Disadvantages: Susceptible to fracture or loss. Lower Hawley’s retainer difficult to insert in some cases due to due to undercut at premolar and molar region. Modification of Hawley’s retainer: Retainer with C clasp on molars: This type is used when there is tight occlusal contact and the occlusal arms may cause occlusal interference, this type is less retention than the conventional one Retainer with long labial bow: Incorporation of labial bow from premolar to premolar rather than from canine to canine, used when there space distal to canine and need to be closed. Retainer with contoured labial bow: The labial bow is contoured and fitted on the cervical margin of the anterior teeth, it is used when more retention is needed in anterior segment, and it gives better control to the anterior segment. Retainer with light elastic on incisors: Use stretched light elastics on anterior segment rather than labial bow, used to close spaces in anterior segment. Retainer with labial bow soldered to the bridge of Adams clasp: The terminal ends of labial bow is soldered to the bridge of Adams clasp, this design allows: =space closure at the extraction premolar area. = avoid the risk of space opening between canine and premolar. Retainer with bite plane: Bite plane is incorporated to the maxillary retainer lingual to the maxillary incisors, that, allow maintenance of normal over bite. Retainer with lingual extension clasp on molar: Extension of lingual clasp instead of Adams or C clasp but its retentive capacity is less, it is indicated when there is tight occlusal contact. Retainer with occlusal rest: Retainer has occlusal rest on molars instead of Adams or C clasp, indicated when there is tight occlusal contact. Begg retainer It was designed by PR Begg, it consists of extended labial bow till the last erupted molars and curves around it to embedded in acrylic base. Advantages: There is no cross over wire thus eliminate the tendency for space opening. Less occlusal interference. Can used in cases of partially erupted molars. Disadvantages: Retention is not good. It can be modified as single arrow head wrap around retainer. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

16. 16 Clip on retainer / spring retainer Made of wire framework that runs labial over the labial surface of the incisors and then pass between canines and premolars and then recurved to lie on the lingual surface of incisors, the both labial and lingual wires are embedded on acrylic. By adjusting the thickness of acrylic pads can have used for correction of rotation commonly seen in incisors lower, it can have used as active retainer. It is indicated when position of lower incisors must be retained after finish orthodontic treatment. Wrap- around retainer It is modification of clip on retainer but it covers all the teeth, it consists of wire that pass along the labial as well as lingual surfaces of all erupted teeth and embedded on acrylic. It is indicated in cases of week periodontal condition. Kesling’s tooth positioner =Developed by HD Kesling in 1945, it covers the clinical crown of maxillary and mandibular teeth with spares of inter-occlusal space and small portion of gingiva. =There are no wire components it is made up of thermoplastic rubber-like material. =It can be used as active retainer when minor adjustment is required. Construction: = an impression is taken after removal of fixed appliance, then poured and duplicated the model. = the teeth are cut off from the model and then reset in an ideal position. = the positioner is then fabricated to this relationship. Advantages: It is durable. Not need activation. Can used as active removable retainer. Disadvantages: Difficulty in speech. Need special equipment for called biostar. Need patient cooperation. Invisible retainer (Osamu’s invisible retainer) Essix retainer =Retainer fully covered the clinical crowns and part of gingival tissues. It is fabricated from ultra-thin thermoplastic materials without any wire components. =It is more esthetic and more accepted by patients, but it requires special equipment called Biostar. =Most likely used in maxillary arch, and more accepted by the patients more than other type of retainer, there are some limitation for this type of retainer: Thickness of the material over the occlusal surface can cause problem especially of the other arch use the same retainer, we can overcome that by use only on arch with this type. Maintain alignment but does not control deepening of the bite. After few months the retainer tend to crack and discolored. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

17. 17 NB: positioner as a retainer: Tooth positioner can have used as retainer after serving initially as finishing device. Positioner does not make a good retainer because: Pattern of wear of positioner is differ than that for retainer. Positioner does not retain incisor irregularities and rotation as well as standard retainer. Overbite tend to increase while wear positioner as a retainer. Fixed retainer Retainers that fixed on the teeth and are cannot removed by the patients. Types: Passive corrective fixed retainer. Bonded lingual retainers. Banded canine to canine retainer. Band and spur retainer. Passive corrective fixed retainer = The fixed appliance that was used for correction can be left passive in place to serve as a retainer. Bonded lingual retainer According to evolution this type classifies into several generations: Blue Elgiloy of dimension 0.032—0.036 inch that introduced in 1944. 1970 lower fixed retainer soldered to 1st molars band or canines ban, by 0.032-inch steel wire. 1994 lingual fixed bondable retainer by 0.030—0.032-inch stainless steel which sand-blasted with aluminum oxide to improve mechanical retention. Recently 0.0215-inch multistrand wire or 0.030-0.032-inch sand-blasted round stainless steel. = Fixed retainer that are bonded on the lingual surface of the teeth, most commonly used in lower anterior region. = Multi-braided stainless steel or blue Elgiloy wire is adapted ligually to follow the contour of anterior teeth. The ends are curved over the canines or premolar as it is bonded. Advantages: Invisible and permit good retention with some movements which is essential for the biologic integrity. Keep extraction spaces closed and maintain the midline diastema closure. Favorable to prevent relapse at 5 years and 10 years post retention. Disadvantages: Deposition of calculus and plaque around retainer. Require extra effort to maintain good oral hygiene. Indication: Prevent incisor crowding. Hold the incisor position. Banded canine to canine retainer Commonly used in lower anterior segment. The canines are fitted with preformed bands, then thick wire is adapted over the lingual contour of anterior teeth and soldered the ends at the canine’s band. Disadvantages: Lack of esthetic due to metallic nature of bands and less of hygiene due to food accumulation. Band and spur retainer Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

18. 18 Used in tooth with labiolingual displacement or rotation, the teeth banded using anterior band material and spurs are soldered onto the bands to overlap the adjacent teeth. Advantages: Very conventional in design. Permit good oral hygiene. Disadvantages: Unaesthetic because metallic parts are visible. Periodontal procedures for successful orthodontic results Healthy periodontium is very important for successful orthodontic results. After finished orthodontic treatment periodontal procedures are useful to preventing relapse. Circumferential fibrotomy: The more sever rotation, the greater amount of relapse. Supracrestal fibers are considered the main cause for relapse, so cutting all gingival fibers surrounded the tooth until depth below the crest of alveolar bone. It is best performed after correction of rotation prior removal of the appliances. In case of gingival inflammation, the procedure is postponed until inflammation is subside . Maxillary frenectomy: Highly attached maxillary frenum (closely approximates inter dental margin) considered responsible for relapse after diastema closure. When stretching the upper lip, the inter dental tissue is blanching. Abnormal frenum should be excised before space closure. This procedure increases the stability of orthodontically closed maxillary midline. Autogenous gingival graft: Supra- periosteal dissection to remove epithelium, connective tissue and muscle fibers. The graft creates adequate zones of attached gingiva, and provide, = enhance the health of affected area. = obtain root coverage after recession. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

19. 19 Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

20. 20 Reorganization of Periodontal and Gingival fibers Widening of PL and disruption of collagen fibers bundles are normal response to orthodontic treatment. Even if tooth movement stops before orthodontic appliance is removed, restoration of PL will not occur as long as the tooth is strongly splinted by rigid orthodontic arch wires. Once the teeth can respond individually to forces of mastication, reorganization of PDL occurs over 3—4 months and the slight mobility present at appliance removal disappears.Gingival fibers are also disturbed by orthodontic tooth movement and must be remodeled to accommodate the new tooth position. It occurs more slowly than PDL.It takes 4-6m for collagen fibers to complete their reorganization. While the elastic fibers remodel extremely slowly & can still exert forces displacing tooth at a year after removal of appliance. Periodontal fibers reorganization takes 3-4m. Gingival collagen fibers reorganization takes 4-6m. Gingival elastic fibers reorganization takes 1 year Therefore, relapse potential can be predicted by evaluation of initial occlusion: teeth tend to move back in the direction from which they came because of the elastic gingival fibers and unbalanced tongue-lip force Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

21. 21 Relapse: Definition: It is the free movement of the teeth toward their original position following cessation of orthodontic force or the tendency of the teeth to undergo changes of position immediately after removal of orthodontic appliances. =Hellman differentiate between relapse and failure as follow: Relapse: return in whole or in a part to the former state of malocclusion (original position). Failure: uncomfortable factors which interfere with attainment the successful result as loss of anchorage or loss of space. Causes of relapse: Occlusal interferences. Placement the teeth outside the area of functional tolerance. Improper retention period after orthodontic treatment that not allow the temporary bundle bone that formed to change into permanent lamellated and not allow the periodontal fibers to re- organize again into the new position. Abnormal tongue size and position. Failure to put the incisors over the basal bone, that lead to recrowding and opening of space. Dento-facial habits. Over expansion of dental arches. Low rate of turn-over of gingival and periodontal fibers. Abnormal proximal contact. Abnormal axial inclination. Unfavorable results of retention: The retaining of the teeth in an abnormal position by permanent retention mat cause permanent damage of the teeth and their supporting tissues as the retainer hold the teeth against direction of functional forces. Recovery after relapse: If despite the utmost care in treatment and retention, relapse or further post treatment maturational changes occur then the following suggestion may be useful: Retreatment may take the form of re-banding or re-bonding some or all teeth. Permanent or prolonged retention is likely preferable after retreatment. The mandibular lingual arch may be used to realign teeth and recon touring the arch. Springs and clasps can be added to removable retainer to assist repositioning and control labiolingual deviations. A headgear or functional appliance may be used against the maxillary arch during growth to provide maintenance or re-correction of relapse toward a class II relationship. Habit training in the form of myo-functional therapy may be beneficial when abnormal habit pattern has attributed to orthodontic relapse. Occlusal adjustment and interproximal reduction may reduce tendency to relapse. In certain cases, the patients can accept minimal relapse rather than continue with prolonged retreatment and retention. Oppenhim, stated, that, retention is one of the most difficult problems in orthodontia; in fact, it is the problem. Relapse in orthognathic surgery. Relapse following orthognathic surgery for correction of skeletal dysplasia may occur due to defect in functional occlusion, because a stable occlusion is mandatory, the following factors must take in account t to prevent relapse: Removal of dental compensation: decompensation. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

22. 22 Correction of tooth mass discrepancies: by interproximal stripping or cosmetic re-contouring. Correction of transverse discrepancies: that allow proper inter-cuspation Over extension of tissues, muscles, submucosal tissues allow high tendency of relapse. In mandibular advancement: the suprahyoid muscle which pull the mandible, so suprahyoid myotomy is recommended Relapse in cleft lip and palate Cases with unilateral or bilateral cleft palate has bony defect in midline or in alveolar segment. Dento-alveolar expansion is carried out before bone graft is done to: =Achievement of good inter cuspation =maintenance the occlusion =allow apace to restore the missing teeth = maintain the integrity of the arch A rigid fixed retainer with wire components extended lingually for all teeth to prevent relapse. How to minimize relapse Pretreatment: Consider extraction of very displaced tooth or rotated tooth During treatment: = maintain arch form = maintain inter canine width = do not alter the position of lower incisor, teeth must position in neutral zone between the extrinsic and intrinsic force =correction of rotation early in treatment =Interproximal enamel reduction for triangular teeth to increase the area of interproximal contact = labial frenectomy before end of treatment = obtain an adequate centroid relationship =maximize interdigitation =Supracrestal fibrotomy for rotated teeth During retention: =Bonded retainer. =active retention for skeletal Cases most likely to relapse: Diastemas Rotations Open bite Risk factors for post treatment relapse: Pretreatment irregularity of maxillary anterior teeth Incomplete alignment during treatment Expansion of maxillary arch segment Rotational displacement Interdental spacing Clinical studies of relapse: Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

23. 23 Relapse in cases treated with 1st premolars extraction: Little et al 1981: =retention period of 2yrs, 65 cases. =mixed CI and II cases. =findings after 1Oyrs =70% became crowded (20% markedly crowded) =mean crowding was 5.25mm (range 1.96-10.4mm =Findings after 20yrs (31 cases): = crowding =1mm on average = mean crowding t to 6.02mm (range 2.38-11 .48mm) = arch length and arch widths reduced Same results in cases with 2nd premolars extraction Relapse in cases treated with serial extraction: Little et al 1990a =15 cases followed for 1Oyrs: =There was no difference between the serial extraction sample & a matched sample extracted and treated after full eruption. Relapse in cases treated by active expansion in mixed dentition: Little et al 1990b =26 cases followed for a minimum 6 years =89% demonstrate crowding =This group showing the worst relapse. Relapse in cases showing generalized spacing: Little and Riedel 1989 = 30 cases treated with edge wise mechanics. =satisfactory stability in 50% of crowded cases. =spacing did not reopen. Stability =Long term stability is a major goal for orthodontic treatment, Sadowsky among others were assumed that, if appropriate orthodontic therapy were provided most of patient exhibit a stable orthodontic results many years after end of retention. =the causes of post-retention relapse are multifactorial. Gorman’s keys for long term stability: Allow lower incisors to align themselves through serial extraction or by using bumper in early mixed dentition. Over correction of lower incisors rotation in early as possible. Re-approximation of incisors early in treatment and again at retention to enhance stability. Avoid increase in inter-canine width during active treatment. Extraction of 1st premolars when mandibular discrepancy is 4mm or greater except when facial esthetic dictate otherwise. The more tooth to move the more likely to relapse. Up-righting lower incisors at 90 degrees however the profile permits. Creating flat occlusal plane and over correction of deep over bite. Supracrestal fibrotomy of severely rotated teeth. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

24. 24 Retention of lower arch until growth is completed. Retainer must be placed the same day of removal. Alexander’s keys for stability: Balanced soft tissue profile. Good inter-incisal angle. mandibular incisors upright on basal bone. Cuspids not expanded. Normal root tip angulation. Uprights mandibular molars. Normal over jet and over bite. Class I cuspid, cuspid supported occlusion. Factors affect long term stability: Careful diagnosis. Treatment outcome: At the end of orthodontic treatment and before retention the orthodontist must be sure that the treated cases fulfill the following criteria: = teeth are placed over the basal bone. = teeth with average norm in angulation and inclination. = no broken contact between the teeth. = good relationship between the arches and good occlusion. = lower incisors should place in normal relation to mandible, FH plane, upper dental arch. = there is no any muscular abnormalities. = causes of malocclusion removed. “adequate inter-incisal angle may prevent overbite relapse and good posterior inter-cuspation prevent relapse of both cross bite and anteroposterior correction” Growth: The maxillary and mandibular growth takes place in slow rate during the adult life. Post pubertal mandibular growth was twice than that of maxilla. According to Bjork the mandibular growth rotation occurs normally in forward direction, but some individual was backward. Normal skeletal cases: According to Bjork, the forward rotation of mandible causes packing of lower incisors due to the restraining influences of the upper. In backward rotation, the lower incisors become retroclined, the posterior teeth not erupted distally and crowding developed anteriorly. Mild skeletal cases: border line cases Depend on the facial type. Short face type: may show: =lower incisor crowding =Deepening of the bite =Relapse of treated class III Long face type: may show: = backward rotation of the mandible = relapse of corrected open bite and deteriorate the classIII treatment. Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

25. 25 Prognathic face: = mandible grow more forward than maxilla. = relapse of cases and dished face. Nanda and Nanda found that, the pubertal growth spurt for patients with skeletal deep bite occurs in average 1.5 to 2 years later than the cases of open bite. For this reason, a longer retention period for skeletal deep bite patients is advocated to counteract the continuing effect of dentofacial growth after the completion of orthodontic treatment. Clinical application: Nature and duration of retention should depend on the maturation of individual. The retention device should be selected according to facial morphology and magnitude and direction of growth. Recommended to make over jet more than zero to act as safety valve for mandibular forward growth 5-Third molars The etiology of post pubertal mandibular crowding in both treated and non-treated cases is a multifactorial: = physiologic mesial drift. = anterior component force of occlusion. = presence of developing third molars. May cause movement of buccal teeth with shortening of the arch and crowding of lower arch. Richardson 1990 concluded that the presence of developing third molars may affect long term stability of cases. Kaplan 1974 concluded that the presence of third molars does not produce a greater degree of relapse after retention period. Broadbent was an early advocate of insignificant role played by third molars in late lower incisor crowding. Clinical application: Careful assessment of the developing third molars should be done. Retention should be continued till eruption of third molars. 6-Type of treatment performed: Extraction and non-extraction treatment: Paquette et al, studied the long term stability 10- 20 years post treatment in both extraction and non-extraction Class II patients, they found: =the majority of cases in both groups showed less than 3.5 mm of lower incisors crowding =significant decrease in inter-canine width in extraction group = the pattern of relapse not related to the type of treatment or post treatment position of denture Sadowsky et al, studied the long term stability in non-extraction patient with prolonged retention they found: = minimal but significant increase in the irregularities of maxillary and mandibular anterior teeth during the post retention stage = some degree of relapse in all variables measured including over-bite and over-jet = the prolonged retention time is an important factor in long term stability B-Arch form, length and width: Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

26. 26 De La Criz et al study Class I and II extraction case found: =a statistical significant reduction in arch length, inter-canine and inter-molar width. = increased anterior irregularities. = arch form tends to change toward its pretreatment shape. C-Late extraction with full treatment: Little et al, concluded that, the only way to ensure satisfactory alignment post treatment is the use of fixed or removal retention for life. D-Serial extraction without treatment: Kinne reported post treatment irregularities after 10 years of serial extraction without appliances. Person et al, showed re-development of crowding, but less pronounced than before treatment. E-Serial extraction followed by appliance therapy: Extraction lead to reduction in arch length and width which unpredictable relative to long term alignment. F-Early mixed dentition treatment without fixed appliances: Early establishment of an inter-molar width and improved occlusion in mixed dentition provides better long term stability post-retention. G-Non extraction with spacing: Mandibular spaces do not open in any case, however the maxillary arch showed more variation, the midline diastema was the most common areas of space recurrence. Of all treatment modalities only three showed acceptable long term mandibular incisors alignment post-retention, these will be: Early mixed dentition treatment with no fixed appliance therapy. Non extraction with generalized spaces. Lower incisors extraction cases. Basic principles; The patient pretreatment lower arch form should be maintained during orthodontic treatment as much as possible. Original inter-canine width should be maintained as much as possible because expansion of lower inter-canine width is the most predictable of all orthodontic relapse. Mandibular arch length decrease with time. The most stable position of lower incisors is its pretreatment position. Fibrotomy is an effective means of reducing rotational relapse. Lower incisors re-approximation shows long term improvement in post-treatment stability Factors affect arch parameter stability according to Kahl- Nike et al: Pretreatment anomaly: Posterior arch constriction Sever crowding Greater mesio-distal diameter of the incisors Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

27. 27 Increased over-bite Were associated post retention relapse of the mandibular width Kind of treatment: Post retention upper arch constriction was significantly higher in extraction group than non- extraction group. Degree of expansion: Moderate arch expansion during treatment, has greater ability to maintain the arch expansion than the severely expanded cases. End of treatment alignment. Clinical application: Extraction treatment are more likely to change the arch form during treatment then non- extraction Must maintained the original arch form and dimension to enhance stability Retention should be an important consideration when planning treatment. 7- Muscles: =The dento alveolar structures are very responsive and adaptive to pressure exerted from muscles of lips, cheeks and tongue. = the balance of oro-facial musculature is very important factor in long term stability of orthodontic outcome. = Moyers stated that, the new occlusion must be in harmony with the muscular pattern. = Rogers introduced an exercise training program for proper stretching the muscles to aid in treatment as well as retention. Clinical application: Removal any abnormal pressure habits. Avoid movement of teeth against the very powerful muscles of cheek and lips in case of over expansion of anterior or posterior teeth. Early treatment during active growth is advantageous because the muscles are still growing, and their origin and insertion is changeable and can easily move in favorable direction. The orthodontist must know the muscular aberration that associated with class II, III, deep-bite and open-bite cases. 8-Reorganization of the periodontal tissues: =Widening of periodontal ligament space and disruption of the collagen fiber bundles that support each tooth are normal response to orthodontic treatment. =Reorganization of periodontal ligament in orthodontically moved tooth is very important for stability. =it usually occurs over 3-4 months of retention except: Collagen fibers that need 4-6 months for reorganize. Elastic fibers that reorganize after one year or more. Clinical application: Holding the teeth with passive arch wire ca not considered the beginning of retention. Retention should be continued at least 12 months to permit reorganization of elastic fibers. Special consideration for the gingival fibers: A-Rotation: Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby

28. 28 The transeptal fibers attached to the labial and lingual surface of the root show tension after one year of retention that may affect the stability, so, the following should be taken: = fibrotomy = early treatment = longed retention A-Extraction site: The transeptal fibers in the extraction site become compressed after approximation of the teeth. This approximation exert force that tends to open the extraction space, so, the following should be taken: = paralleling the roots at the extraction site. = transection of the transeptal fibers. = prolonged retention. 9-Age: Generally, early treatment is preferred because: Higher rate of cell metabolism, bone and periodontal ligament turn over. Higher adaptability of the dento-facial structure to the new situation. In adult patient, the cell population and vascularization is reduced which decrease the rate of turn over, so the retention should be longer in adult than in adolescence. 10-Sex: Female patients which suspected to hormonal changes as in pregnancy and postmenopausal, which have estrogen defect that lead to bone loss and osteoporosis. 11-Duration of retention: Failure to detect and select the appropriate retention time affect the long term stability. 12-original malocclusion: Deep overbite cases: relapse tends to occurs in 1st 2 years post retention and maintenance of inter-canine width is thought to increase stability. Class II division 1: has slight change in overjet toward pretreatment value when compared with other malocclusion. 12-Other factors: = caries. = abnormal pressure habits. = improper restoration. = periodontal problem. = neglecting the orthodontic annual visits. Thanks Retention Retention, Relapse and S , Relapse and Stability in tability in orthodontics orthodontics Dr. Mohammed Alruby Dr. Mohammed Alruby