excessive over bite in orthodontics

1. 1 Excessive over bite in orthodontics Excessive over bite in orthodontics Prepared by: Prepared by: Dr Mohammed Alruby Dr Mohammed Alruby ليحرلا دارا نم ديب كسمت لا نكلو ادحا رجهت لا E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

2. 2 Over bite: it is vertical relationship between maxillary and mandibular anterior teeth in centric occlusion Significant of over bite: 1-Proper extent of over bite relation permits a functional mandibular movement against the maxillary arch without interference 2-Proper over bite relations of incisors and canines enables the posterior maxillary and mandibular teeth to only contact upon centric, this canine guidance serves in preventing trauma from occlusion that may disturb the periodontium and TMJ Concept of ideal over bite: In normal occlusion the maxillary central incisors slightly overlap the mandibular one, this overlap is either describe in mm or as percentage of mandibular incisor crown length overlapped by the maxillary central incisors. Since the crown length of lower incisors significantly varies in individuals, the expression of the overbite in percentage is more descriptive and accurate. Normal overbite ranges from 5% to 25% overlap of mandibular incisors. The ratio 20% to 40% overlap without any functional problem during various mandibular movements may also considered normal Over jet: it is a horizontal relationship between maxillary and mandibular teeth in centric occlusion Causes: 1-Smaller mandibular arch than maxillary one that result in overhanging of maxillary teeth relative to mandibular one 2-The lingual angulation of crowns of mandibular teeth relative to crowns of maxillary teeth 3-Greater parabolic curvature of maxillary arch Significant of over jet: 1-Establishment of faciolingual inter-cusp relation when the mandibular teeth come into centric occlusion 2-Protects the cheeks, lips and tongue during mastication by preventing them from being interposed between maxillary and mandibular teeth while they approach their occlusal contact Deep over bite: excessive over bite: It is a combination of skeletal, dental and neuromuscular features that causes increase amount of vertical overlap in the incisor region It is a complex orthodontic problem, so the correction of this problem needs a careful diagnosis and treatment planning and careful selection mechanics Prevalence of deep bite: Vertical deviation from the ideal overbite are less frequent in adults than children but occurs in half of adult population. Deep overbite found in 20% of children and 13% of adult while open bite while open bite occurs in less than 1% There is striking difference between the racial group in vertical relationship, excessive overbite is nearly twice as prevalent in whites as blacks, while open bite is five times more prevalent in blacks than whites E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

3. 3 Factors considered in the development of deep overbite 1-Hereditary factors: One of the important factor for the development of deep bite or other malocclusion because it controls the development of craniofacial skeleton Several studies indicate that: - the position of maxilla and mandible - size of maxilla and mandible, cranial base - anterior and posterior facial height -length of ramus -tooth size and morphology -direction of growth -gonial angle shows a component of genetic background 2-Pressure habit: as lip sucking and lip biting that lead to increase over jet followed by lack of incisal stop, that lead to development of deep bite dental deep bite: in class I malocclusion the degree of over bite seemed to be controlled by dental factors as: 1-length of clinical crowns at the incisor region 2-length of clinical crown of maxillary first molars and molar cusp height 3-the incisor position, the degree of over jet and inter-incisal angle 4-mesial drifting of first molars with collapsed anterior segment 5-anomalies of tooth size (mesio distal width) and number 6-malposition of the teeth 7-canine position. Skeletal deep bite: In skeletal deep bite the skeletal features are combined with the dental factors. Most of dee bite cases are associated with: 1-anterior posterior dysplasia especially skeletal class II, with lack of incisal stop that lead to development of deep overbite 2-deficient lower face height and defect ramus vertical growth ---- skeletal deep bite type 3-loss of vertical growth coordination between cranial base and posterior dento-alveolar segment 4-the posterior chain of muscles is more anteriorly and strong that lead to greater depressive force on the posterior teeth that lead to lack of normal eruption, normally the teeth are in state of equilibrium under the muscles and eruption force 5-excessive binding of posterior cranial base that cause forward positioning of glenoid fossa often directly below sella that lead mandible to rotate upward in anticlockwise rotation manner 6-idiopathic vertical dysplasia ------ idiopathic short face mandibular growth rotation and deep bite: the potential risk for the forward growth rotation during active growth period is the developmental of skeletal deep bite, that is largely influenced by the incisor relationship, for example: if there is proper incisor relationship and adequate incisal stop, there will be a great chance that deep bite is not developed E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

4. 4 Bjork reported that, under ideal circumstances, the fulcrum for the mandibular growth rotation will located at incisors, in such circumstances the incisal stop will act as safety valve against Deeping the bite If the incisal stop is lacking for any reason, the patient often developed a skeletal deep bite, because the fulcrum of rotation will move farther back to the premolar region Complication (sequelae) of deep bite: 1-poor facial esthetic 2-periodontal disease especially in lower anterior segment due to crowding and traumatic injury of gingival tissue by the extruded teeth 3-wear of the teeth as a result of bruxism 4-sometimes pain due to muscle spasm. 5-Traumatic occlusion and translocated mandibular overclosure, the upper incisors act as a guiding factor in mandibular overclosure (in overclosure the mandible is locked behind the maxillary anterior teeth, this may affect normal mandibular growth) 6-TMJ dysfunction, abnormal position and inclination of anterior teeth guide the mandible to overclosure which causes irreparable damage in TMJ TMJ x-ray shows: posterior displacement of the condyle which moves behind the articular disc occluding on the nerve fiber of the retrodiscal pad Clicking and crepitus sounds developed early and pain later on, additional pain caused by muscle spasms and reflex action between the posterior fibers of temporalis and lateral pterygoid muscles Path of mandibular closure: in cases of deep bite with class II div 2 = some authors believed that there is true posterior displacement of the mandible when closing from rest position to occlusion = the initial contact of the lower incisors with the palatal surface of upper incisors was thought to produce a reflex avoiding action displace the mandible posteriorly that has deleterious effect on the function of TMJ and produce painful symptoms = Ballard has shown that, in most cases, there is habitual mandibular rest position which is downward and forward from the true postural position Closing from this forward position into occlusion gives that false illusion of posterior mandibular displacement The purpose of treatment: 1-To improve the facial esthetics 2-To prevent periodontal disease 3-To improve masticatory function and prevent traumatic occlusion 4-Prevent mandibular overclosure and thus allows forward mandibular growth 5-To maintain normal function 6-To alleviate pain caused by muscle spasm and TMJ Diagnosis of excessive overbite The determination of the causative factors is the most important step in diagnosis of excessive overbite Successful treatment of deep bite depends upon careful analysis of the factors contributing to the problem Excessive overbite is rarely seen as a separate or isolated entity, but most frequently seen as a part of total malocclusion E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

5. 5 Detailed clinical examination of the dentition, occlusion, jaw movement and soft tissue profile is very important Clinical examination: 1-Extra-oral examination: a-Dental deep bite Patients with dental deep bite may have normal facial proportions, no abnormality detected in frontal or profile view if another condition not existing b-Skeletal deep bite: the patient characterized by: 1-Broad square face, the width equal to the length 2-Competent lips 3-Broad nose with enlarged nasal apertures that present clearly in class II division 2 4-Obtuse nasolabial angle as in case of class II div 2 but in class II div 1 the angle is more acute 5-Wide mouth in most cases 6-The upper and middle 1/3 of the face are of normal height while the lower third of face is short. The lower facial height is shorter than that present in most cases. (normal ratio: UAFH: LAFH= 45% : 55% ) 7-Well-developed pogonion (prominent chin) with accentuated labiomental sulcus 8-When the mandible in physiologic rest position, the maxillary incisors are minimally exposed or completely hidden behind the lower lip, when the patient speck or smile there is a difficulty in showing his frontal teeth, the patient has an edentulous appearance On the other hand, many deep bite cases have high lip line exposing much of anterior teeth or gingival tissues when smiling (gummy smile) 9-The chain of muscles (masseter, temporalis, internal pterygoid) are attached anteriorly to the mandible stretching it vertically in nearly straight line. The molar lies under the impact of these muscles that gives a greater depressive force on the dentition that lead to lack of normal eruption, that present clearly in class II div2 10-The skull is brachycephalic, the forehead is prominent, the nasion is deeply seated between frontal and nasal bones 2-Intra-oral examination: = Both dental and skeletal deep bite may have the same intra-oral features. In dental deep bite the problem lies mainly with the dentition, the majority of this type are created by: a-Loss of permanent teeth that lead to collapse of anterior segment ---- change in their inclination ------- lack of incisal stop ------- deep bite b-Mesial drift of posterior teeth c-Teeth size discrepancy = Gingiva: gingivitis and marginal periodontitis are common in lower anterior segment = Tongue: the tongue of normal size and behavior, it set posteriorly within the large pharyngeal space and does not interfere with breathing, that is more characteristics in class II div 2 than any other classes = Teeth: in some rare classes the teeth smaller than normal and there are abnormalities in tooth morphology = The long axis tends to be parallel as in class II div 2 and generally there is a large inter-incisal angle E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

6. 6 = Upper arch is more characteristic in class II div 2 (wide, square, with flat palatal vault), but in class II div 1 upper arch is avoid with high palatal vault. = The lower arch shows accentuated curve of spee Molar relationship: deep bite associated most commonly with class I, II, div 1 and2 and less commonly in class III (reversed deep bite) Model analysis: Excessive over bite with varying degrees of over jet a-The lower arch shows excessive curve of spee and crowding of anterior segment b-The maxillary arch is wide in class II div 2 but more ovoid in div 1 c-The maxillary arch rarely shows crowding, the maxillary teeth may space as in class II div 1 d-The palatal vault is broad and flat as in class II div 2, high in class II div 1 Cephalometric analysis: In dental deep bite (simple deep bite) the depth is largely determined by the dental factors, for example, dental deep bite in class I malocclusion has the following criteria: a-Abnormal inclination of upper and lower incisors b-Large inter-incisal angle c-Excessive over bite Criteria of skeletal deep bite: a-The four planes of the face (cranial base plane, palatal plane, occlusal plane, and mandibular plane) are horizontal and nearly parallel b-Small cranial base angle c-Small gonial angle d-Small XI angle e-Large mandibular arc angle, -------- 26 -+4 (ANS. XI. PM) f-Anterior upper facial height within normal range g-Anterior lower facial height is reduced than normal h-The facial breadth is nearly equal to the anterior total facial height; the anterior total facial height is nearly equal to the posterior facial height that give square face. i-Small SN – MP angle and FMPA j-The posterior maxillary dento-alveolar height is decreased (line perpendicular to palatal plane and tangent to the mesio-buccal cusp of upper first permanent molar k-The posterior mandibular dento-alveolar height reduced significantly l-Upper anterior dento-alveolar height may be: -Normal: which the lower anterior dento-alveolar increased or may be reduced (vertical maxillary deficiency) so intrusion of maxillary incisors is contraindicated -Increased: (gummy smile): in this case the lower dento-alveolar height may be normal so intrusion of upper incisors is the treatment of choice m-More wide symphysis Treatment of deep overbite There are certain basic methods for treatment of deep overbite: 1-Levelling of arch through intrusion of anterior teeth and extrusion of posterior teeth (combination) 2-Intrusion of upper and /or lower incisors E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

7. 7 3-Labial inclination of incisors 4-Extrusion of molars The primary factor in the treatment planning is to decide whether correction of deep bite requires intrusion of incisors or extrusion of molars or both, so the selection of proper method depending on the following basic consideration: 1-Inter-labial gap: The inter-labial gap between the upper and lower lips in relaxed posture (normal from 2 – 4mm) larger value contraindicate the extrusive mechanics, in this cases intrusion of incisors is the treatment of choice, since molar extrusion may increase this gap the lead to poor esthetic in addition to difficulty in closing lips without active contraction of lips 2-Incisors stomion distance: The distance from incisal edge of upper incisors to the lower border of upper lip (normally 2 -4mm) normal value contraindicate intrusion of maxillary incisors, while larger value that give gummy smiling and indicate intrusion of maxillary incisors 3-Lower incisors lower lip relation: In normal individuals, the lower lip covers the lower incisors in a relaxed position, if can be seen, intrusion of lower incisors is the treatment of choice. 4-Vertical relationship: Increased anterior facial height and vertical growth tendency contraindicate the extrusive mechanic When mandibular plane angle is low, the extrusive mechanics is the treatment of choice Clinically the extrusion of posterior teeth results in: - increase in lower face height - clock wise rotation of the mandible -increased inter-labial gap and reduction in anterior overbite 5-anterior posterior relationship: ** in class I and class II div 2 with reduced lower anterior facial height, the extrusion of posterior teeth is the treatment of choice ** in class II div 1 with large lower anterior facial height, the extrusion of posterior teeth increases the functional, esthetic and stability problem ** in class III deep bite cases, the extrusion of posterior teeth is the treatment of choice, because it corrects the deep bite and reduce the mandibular prognathism. 6-Occlusal plane: One of the objectives of the treatment is to provide the patient with flat occlusal plane, this objective if not considered along with lip and vertical facial height consideration may result in unpleasant and unstable conditions In an individual where the vertical position of the posterior teeth cannot be changed and anterior teeth need intrusion because of lip considerations, a steep type occlusal plane may be created between anterior and posterior teeth On the other hand, a slight or moderate curve of spee in the mandibular arch may be left intact if the lip and facial height consideration demand treatment by intrusion of maxillary incisors 7-Inter-occlusal space: It is the distance between the occlusal surface of upper and lower teeth when the mandible in relaxed position (normally 2 -4mm) Normal inter-occlusal space contraindicates the extrusive mechanics, on the other hand, when inter-occlusal space is larger than normal, extrusion of posterior teeth is the treatment of choice 8-Muscle force: E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

8. 8 Muscular deep bite is very difficult to be treated by molar extrusion, since the extrusive mechanics must work against large occlusal force 9-Age of patient: Early treatment of deep bite is more successful as it utilizes the vertical growth vector in correction of deep bite. Molar extrusion in early treatment may has no adverse effect on AFH or FMA because the increase in AFH as a result of molar extrusion is compensated by increase in PFH through the condyle growth. Treatment mechanics 1-Primary dentition: Excessive over bite in primary dentition is most likely to have a skeletal basis, an excellent result with maxillary bite plate during this period. The activator can also be used to direct vertical alveolar growth, reduce the inter-occlusal distance by extrusion of posterior teeth and improve the skeletal morphology. 2-Mixed dentition: Deep bite with class I molar relationship occur immediately after eruption of permanent incisors, then become reduced with full eruption posterior teeth. Several factors may consider in the development of deep bite as: a-Vertical over development of incisor region b-Under development of posterior region ** if deep bite caused by first factor ----- intrusion of incisors is the treatment of choice using upper and /or lower utility arches ** if deep bite caused by the second factor ----- extrusion of molars is the treatment of choice by using maxillary bite plane, if there is adequate freeway space for their use, this help eruption of molars, correction of deep bite and reduction of curve of spee Deep bite with class II molar relationship, the treatment directed to all the class II problem. Activator is the treatment of choice for vertical and anterior posterior dysplasia in class II cases, the early treatment with activator improve the vertical and anterior posterior growth factors Deep bite with class III and anterior cross bite (reversed deep bite): the correction of reversed deep bite depends mainly on the correction of reversed over jet. The incisors should be placed in a correct anterior posterior relationship by Proclination of upper incisors and / or retroclination of the lower incisors, inclined planes, reversed activator, Frankel III, can be used for the treatment. In class III deep bite, the extrusion of posterior teeth is the treatment of choice since it will reduce the deep bite as well as the mandibular prognathism 3-Permanent dentition: Labial inclination of incisors Intrusion of upper and /or lower incisors Extrusion of molars a-Labial inclination of incisors: This can correct the simple deep bite associated with abnormal axial inclination of incisors b-Intrusion of upper and /or lower incisors: This method is used in correcting the majority of deep bite cases 1-The maxillary utility arch: E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

9. 9 Indication: -Deep bite cases with high lip line and gummy smiling -Anterior vertical maxillary excess with high FMA Contraindication: -Low lip line -Reduced incisor stomion distance and low FMA Construction: Wire 0.016 x 0.022 stst which design to deliver force from 120 to 150gm of intrusive force upon incisors Torque should be incorporated to the wire in the anterior segment or using pre-torqued bracket to avoid root resorption of incisors. Toe in bends 30 degree should be placed to maintain ideal molar position. Tip back bends 45 degree is made just anterior to the molar tube to deliver about (120—150) gm intrusive force, anterior teeth should be ligated together with ligature to prevent their distal movement Anchorage preparation: To prevent the reciprocal extrusive on posterior teeth, the anchorage should be reinforced by: a-Banding of premolars and 2nd molars and using buccal sectional arch to tie these together b-Using transpalatal arch which serve to increase the anchorage value, and prevent palatal tipping of molars c-Using of high pull headgear because its upward and backward vector that tend to counteract the extrusive vector of the utility arch, so the triple molar tube should be used, one for the buccal sectional arch, one for the base arch and the third for the inner bow of the headgear. Intrusive force for individual teeth: -25gm for each maxillary incisors -20gm for mandibular incisors -50gm for each maxillary canine -40gm for each mandibular canine The activation range is 3 to 4 weeks and the base arch should intrude the incisors 1mm /month. The use of proper recommended force provides more controlled intrusion and minimize the risk factors, and also may eliminate the use of headgears 2-Lower utility arch: It is similar to the upper utility arch but differ in the following: a-It constructed from 0.016x0.016 stst wire because the intrusive force for lower incisors is less than that of upper (75gm) b-Incorporated buccal root torque to utilize an anchorage for lower arch Side effect of utility arch and prevention: 1-Extrusion /or distal tipping of the molars, both effects can cause bite opening and steepness of mandibular plane, this risk factor specially with vertical growth pattern and can be prevented by use of high pull headgear. N: B: cervical headgear causes extrusion of molars and opening rotation of the mandible so that it is contraindicated in the treatment of class II vertical pattern, however of its efficiency in reducing maxillary prognathism, some authors developed modification for its use as: = applying cervical headgear to maxillary molar without any maxillary appliance E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

10. 10 = using lower utility arch with buccal root torque to create a cortical anchorage and prevent lower molar extrusion = bending of outer bow 20 degree downward 2-Utility arch has the potential to tip molars lingually and decreasing the inter-molar width. This can be solved by using transpalatal arch in maxilla and lingual arch in the mandible. 3-By using utility arch there is high potential to cause root resorption of maxillary incisors due to using of heavy force and flushing of roots against labial or palatal cortex, this can be alleviated by produce proper force magnitude and introducing a proper torque or using pretorqued brackets. 4-By using utility arch there is proclination and flaring of incisors. This effect can be prevented by tying back the arch to the molar tubes 5-Spacing of incisors may occurs, so the incisors should be tied together with figure 8 ligature c-Extrusion of the molars: Indication: -Low FMA -Normal growth pattern -Class II div 2 and class III -Large inter-occlusal space -Small inter-labial gap Contraindication: -Vertical growth pattern -Small inter-occlusal space -Large inter-labial gap Mechanics: 1-Maxillary bite plate: flat acrylic plate built in palatal surface of the maxillary incisors and soldered to the molar bands, when the mouth closed the mandibular incisors come in contact to this plate causing distocclusion of posterior teeth which allows acceleration of passive eruption of posterior teeth. Bite opening should not exceed 2mm to avoid TMD and myofunctional changes. With progress of treatment, small increment can be added to the acrylic plate to allow further extrusion 2-Reverse curve of spee: nitinol reverse curve is excellent method for reduction of overbite and levelling curve of spee. Rectangular wire is preferred because there is lack of control over the round wire, Disadvantage: Flaring and proclination of incisors Abnormal axial inclination of molars Intrusion of anterior teeth 3-Inter-maxillary elastics: as class II, III, cross elastics and vertical elastics 4-Magnets 5-Cervical headgear 6-Functional appliances: that help in positioning the lower jaw forward to an edge to edge bite and dis-occluding the posterior teeth which free to erupt, eruption can be augmented by using elastics during fixed appliance mechanotherapy Side effect of extrusive mechanics: 1-Increase lower anterior facial height E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

11. 11 2-Clockwise rotation of the mandible and increase the FMA 3-Increase the facial convexity 4-Increase the muscle tone and increase the possibility of relapse N: B: occlusal equilibrium must be made after end of active treatment and after end of retention period Retention: One of the problem of deep bite treatment and must be made carefully to prevent relapse after orthodontic treatment so the following can be made: -Build a potential bite plate into the retainer which lower incisors contact to it for several years after removal of fixed appliance -Put the incisors in a correct relationship, that allow proper incisal stopper -Use fixed retainer from canine to canine or from premolar to premolar to preserve the vertical dimensions of the incisors after treatment The following factors must be kept in mind when planning retention in deep bite cases: 1-Age: deep bite correction is usually achieved by intrusion of incisors and extrusion of posterior teeth. In growing patients, the active vertical growth during deep bite correction ensure greater stability 2-Facial type: certain facial types have greater potential for permanent correction than others Hyper-divergent facial type usually exhibits more favorable reaction to over bite correction when compared with hypo-divergent facial type 3-Molar extrusion and incisor intrusion: any eruptive movement beyond the inter-occlusal space might not be able stable due to strong posterior occlusion or muscle stretch especial in low angle individuals There are some factors that can lead to relapse of incisors intrusion as: -Canting occlusal plane -Incomplete levelling of curve of spee -Forward rotation of mandible 4-Inter-incisal angel: Riedel suggested that large inter-incisal angel at the end of treatment is associated with relapse of deep overbite Nanda and Burzin suggested that, the following factors are important for stability: -Ideal axial inclination of incisors at end of treatment -Optimum inter-incisal angle -Incisal stops -Guidance between the maxillary and mandibular incisors in essential for maintaining overbite correction == inter-incisal angle can be higher in dolichol-facial patterns and less in brachy-facial patterns == angle of 125degree to 135 degree ensure good stability for deep bite correction Orthognathic surgery for deep bite cases Some cases of deep bite have severed skeletal discrepancy that cannot treated by orthodontic appliance alone so the orthognathic surgery is indicated: 1-To improve the efficiency of orthodontic mechanics 2-To improve the facial esthetics 3-To provide long term stability == lefort osteotomy with maxillary impaction E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

12. 12 == mandibular autorotation == vertical reduction and advancement genioplasty == sagittal split osteotomy with set back as in cases of class III mandibular excess == lefort osteotomy with maxillary impaction and advancement as in class III maxillary deficiency N: B: Bite plates for extrusion of posterior teeth: 1-Removable bite plates consist of an acrylic plate form anchored to the maxillary dentition with arrow head (adams or crip clasp). Anteriorly, there is a labial bow which helps to stabilize the bite plate and contract the teeth at the incisal one third 2-Fixed or bonded bite plate, consist of blocks of composite or glass ionomer cement that can bonded on the lingual surface of maxillary incisors to dis-occlude the posterior teeth (no need for patient cooperation. N: B: Combination of intrusion and extrusion: By positioning anterior brackets more occlusally and posterior bracket gingivally or by using reverse curve of spee arch wire. However, there is no definite control over such mechanics (intrusion in anterior teeth and extrusion in posterior teeth) Drawbacks: = change axial inclination in buccal teeth = flaring of incisors = extrusion is more easily accomplished than intrusion in reverse curve of spee N: B: Implant for deep bite correction; Mini-implant can be used effectively for enmass intrusion of anterior teeth Treatment procedures 1-Intrusion arch: = An intrusion arch can be made from 0.016 x 0.022 or 0.017 x 0.025 nickel titanium Connecticut arch wire (CAN) which is performed arch active unite and passive unite is stiff rigid segmental wires, 0.017 x 0.025 stst in molar and premolars bilaterally. = The intrusion arch is activated by placing 30-degree gingival bend 2 – 3mm mesial to the molar tube so that the wire pass passively in the vestibular sulcus, activation is accomplished by bringing it occlusal and tying it to the anterior segment as a point contact. = The intrusion arch can also be tied back or cinched to prevent flaring of incisors if the intrusive force is being applied anterior to the center of resistance of the incisors E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

13. 13 As a general guide line 10 to 15gm of force per-incisors is acceptable to prevent posterior side effect = Another useful clinical application of intrusion arch is in preventing the side effects associated with canine retraction as: rotation, flaring and extrusion of canine = However, when arch wire with low load deflection rate is used it tends to deform, leading to undesirable side effect on anterior teeth in form of intrusion of incisors which term as iatrogenic deep bite which means deep bite induced by the clinician. ((development of deep bite during canine retraction (sliding mechanics) due to occlusal deflection of arch wire)) 2-Utility arch: Ricketts: Similar to CTA but the difference is that for intrusion, the utility arch is tied into the incisor bracket which create two couple of force system, the moment of which tend to tip the incisor crown facially and the molar distally The facially tipping of incisors can be avoided by: a-Cinching or tying back the intrusion utility arch b-Torque bend or twist bend in anterior segment, this will increase the intrusive force on the incisors and intrusive force on molars E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

14. 14 3-Three pieces’ intrusion arch: Use segmental mechanics that intrude and retract the incisors at the same time a-Passive segment at molar and premolars b-Two active segment0.016 x 0.022 or 0.017 x 0.025 CAN wire activated by placing 30 /45degree gingival bend 2 to 3 mm mesial to the molar tube The gingival bend can be increased or decreased based on the desired amount of intrusive force. The wire of anterior part is hooked to the distal extension on the anterior segment Use of class I elastics to the posterior segment 4-K – SIR arch: It is continuous 0.019 x 0.025 TMA arch wire with closed loops at extraction site (simultaneous intrusion and retraction) can be achieved. 5-Curve of spee: It mainly causes extrusion of posterior teeth, there may be undesirable changes in the axial inclination of buccal teeth and flaring of incisors. N: B: Relative intrusion: -Curve of spee -K-SIR arch -Three-piece intrusive arch -Utility arch -Intrusion arch - Absolute intrusion: -micro-implant mechanics -j- hooks headgear N: B: Path of mandibular closure: in cases of deep bite with class II div 2: = some authors believed that there is a true posterior displacement of the mandible when closing from rest position to occlusion. The initial contact of lower incisors was thought to produce a reflex E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby

15. 15 avoiding action displace the mandible posterior, that has a deleterious effect on the functions of TMJ and produce painful symptoms = Ballard has shown that, in most cases, there is habitual mandibular rest position, which is downward and forward from the true postural position. Closing from this forward position into occlusion gives the false illusion of posterior mandibular displacement. E Ex xc ce es ss siiv ve e o ov ve er r b biite te in in O Orthodontics rthodontics Dr Mohammed Alruby Dr Mohammed Alruby