lower incisor extraction

1. 1 Lower incisors extraction Lower incisors extraction Prepared by Prepared by Dr. Mohammed Alruby Dr. Mohammed Alruby L Lower ower incisor extraction incisor extraction Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 = introduction = diagnosis and treatment plane = contraindication = advantages. = dis advantages. = Case selection = retention. = stability. L Lower ower incisor extraction incisor extraction Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 Lower incisors extraction Introduction: Several approaches for crowded mandibular anterior teeth are currently employed: 1- distal movement of posterior teeth. 2- labial movement of incisors teeth. 3-inter-proximal enamel reduction. 4- removal of premolars. 5- lateral movement of canines. 6- removal of one or two incisors. 7- Or various combination of above. Selecting the best treatment is often difficult and all guide lines do not apply to every case. = lower incisor extraction to solve mandibular crowding is not a new idea: In 1904 jaackson had illustrated a case where on incisors had been previously removed and he chose to remove a second one because, the remaining three were crowded and the inter-canine distance was too narrow for their alignment. = in 1921, case extracted 2 lower incisors in periodontally affected and close the extraction space orthodontically. = after reviewing 1- years post retention records of pts. who had two mandibular incisors removed, Reidel observed that the arches in these pts.appears less crowded post retention than those of similar patients who had been treated with the premolars extraction, he added, that the extraction of two mandibular incisors may satisfy the requirements of maintaining the arch form without expansion of inter-canine width. N:B: with non-extraction treatment (expansion) or premolar extraction therapy, the original inter- canine width must be increased in order to gain adequate alignment and arch form. == Fisher 1940 demonstrate several cases with two incisors extraction plan and no retention. == Schwarz reviewed 20 years post retention records of one pt.who had congenitally missing two mandibular incisors, he was surprised to observe good long –term stability. == Solzman, reviewing Edward Angle’s philosophy regarded that extraction of an incisors, when the tooth was sound, to be an excusable. == Angle warned that extracting on incisors, as advocated by some, would lead to a less acceptable harmony between the occlusal planes of the remaining teeth in addition to an abnormal incisor over bite. *** Diagnosis and treatment plane: According to Owen 1993: the following diagnostic criteria are usually required for single mandibular incisors extraction: 1-Class I molars relationship, indicating that the final buccal inter-digitation will be acceptable. 2-Permanent dentition. 3-Moderate crowding lower incisors: sever---- extraction, mild-------non extraction 4-Mild or no crowding in upper arch which allow correction by inter-proximal reduction alone. 5-Acceptable soft tissue profile, because there will be minimal change in the maxillary arch. 6-Minimal to moderate over bite and over jet. L Lower ower incisor extraction incisor extraction Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 7-No growth potential. In growing patients, non-extraction therapy should be considered before incisors extraction. 8-Tooth size discrepancy of more than 5 mm anteriorly, such as missing or peg shaped laterals that can be used to resolve tooth size discrepancy without stripping. 9-Loss of original tissue and bone overlying the labial surface of incisors root. *** Orthodontic indication for extracting mandibular incisors: 1-Supernumerary teeth: = prevalence of supernumerary teeth in mandibular incisors region is 2% of total supernumerary and it is the lowest in the oral cavity. = identify the supernumerary teeth could be difficult because, there is no significant between the incisors. 2-Congenital missing mandibular incisors: = some orthodontist found that the congenital missing of both mandibular central incisors is advantageous, as the extraction of mandibular centeral incisors is considered as the treatment of choice in crowded Class I malocclusion especially when there is tooth size discrepancy. 3-Severe Bolton discrepancy: = Black 1902 was one of the 1st investigators to measure tooth sizes, Bolton analyzed the relationship between the mesiodistal tooth width of maxillary and mandibular teeth and calculate ant.ratio and over all ratio. 4-Moderate Class III malocclusion with anterior open bite: = in patient with Class III malocclusion, correction is aimed at achieving Class I relation and normal over jet and over bite. = removing a single mandibular incisor tooth in Class III malocclusion is indicated when the mandible is over size and the anterior percentage relation (APR) (Bolton) can be converted to acceptable figure. The occlusal area of the mandible is reduced and the extracted incisor is replaced by adding the premolar to anterior segment that will reduce the APR and over bite. NB: APR: if less than 18% after extraction may produce an open bite. 5-Ectopic eruption of incisors: The presence of ectopic mandibular lateral incisor can result in root resorption and early exfoliation of deciduous canine and 1st molar if not treated early may develop into partial or complete transition of permanent canine. *** Contraindication: 1-Class II division 2 with deep bite: all cases with severe deep bite, severe crowding with no size discrepancy and excessive over jet. 2-Premolar extraction: all cases require premolar extraction while canine Class I. 3-Triangular lower incisors: and minimum crowding with less than 3mm, should be treated without extraction by stripping of incisors to prevent reopening of spaces, and loss of inter- dental gingival papilla between the remaining incisors. 4-Excessive over bite: when the diagnostic set up demonstrate that lower incisor extraction may result in excessive over bite. 5-High insertion of labial Frenum: in case high insertion of lower labial Frenum may cause gingival recession when trying to move lower incisor to the Frenum area. 6-Gingival recession: is a predisposing to periodontal disease especially when the roots of the adjacent teeth are not positioned close together. L Lower ower incisor extraction incisor extraction Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 *** Advantages: Brandt and Safirtein 1975, stated that the following advantages of mandibular incisors extraction: 1-Maintain the overall arch form. 2-Improve the root parallism. 3-Extraction within the area of crowding, so it allows for rapid space closure. 4-Simple treatment mechanics, that can achieve good results within short period of time. 5-Low risk of anchorage loss. 6-Reducing the retention time. 7-Minimize the change in profile. 8-Easy alignment of anterior segment. *** Disadvantages: Brandt and Safirtein 1975 stated the following disadvantages of mandibular incisor extraction: 1-Occlusion not always perfect Class I. 2-When the central incisors were extracted, there is tendency to space open. 3-Mesio-distal dimension between maxillary and mandibular teeth------ there is slight maxillary anterior teeth excess that can result in: Increased over jet Increased over bite Class III canine relationship, this problem can be resolved by interdental enamel reduction in maxillary anterior teeth 4-Absence of mandibular midline. *** Case selection for treatment: Certain criteria will aid in the selection of suitable cases: 1-Normal maxillary dentition. 2-Class I malocclusion. 3-Good buccal inter-digitation in which there is severe lower anterior crowding. 4-Provided that the lower anterior arch length deficiency is 4mm to5mm. 5-The anterior ratio is more than 83mm. Retention: = retention is being accomplished with maxillary and mandibular removable retainers. = the maxillary retainer may have an anterior bite plane to prevent over bite relapse. = in critical case lower fixed retainer canine to canine is used. Post retention stability: = Riedel et al 1992: suggested that the extraction of lower incisors can provide greater stability in anterior area in absence of permanent retention. = in long term cases with extraction of lower incisors show less crowding relapse after retention than cases treated with premolar extraction due to: 1-Low effort on anchorage unite. 2-Muscle pressure is less likely to produce instability. = Valinoti 1994 suggested that the extraction of lower incisors is less likely to have crowding relapse after retention because the incisors is located closest to the area where the problem is located. L Lower ower incisor extraction incisor extraction Dr. Mohammed Alruby Dr. Mohammed Alruby