Mandibular incisor extraction for management of class I malocclusion-A case report

Introductions: A class I malocclusions is a condition in which the tip of mesiobuccal cusp of first maxillary molar occlude in the anterior buccal groove of mandibular first molar tooth, however malocclusion presents on other teeth.Cephalometric specific classification also present to conclude the skeletal base as class I malocclusions.One of the most critical decisions in treatmentplanning is whether to extract teeth. This extraction decisions also influences the patients treatment seeking behavior and co-operations.To conclude this decision of extraction for orthodontic corrections could easily be made on the basis of Bolton’s tooth tissue ratio analysis for a specific populations with comparing its norm. Several approaches for crowded mandibularanterior teeth are currently employed: distalmovement of posterior teeth, lateral movement ofcanines, labial movement of incisors, interproximalenamel reduction, removal of premolars, removalof one or two incisors, and various combinationsof the above. Selecting the best treatmentis often difficult, and all guidelines do not apply toevery case.


Introductions:
A class I malocclusions is a condition in which the tip of mesiobuccal cusp of first maxillary molar occlude in the anterior buccal groove of mandibular first molar tooth, however malocclusion presents on other teeth. 1 Cephalometric specific classification also present to conclude the skeletal base as class I malocclusions. 2 One of the most critical decisions in treatmentplanning is whether to extract teeth.This extraction decisions also influences the patients treatment seeking behavior and co-operations. 3To conclude this decision of extraction for orthodontic corrections could easily be made on the basis of Bolton's tooth tissue ratio analysis for a specific populations with comparing its norm. 4veral approaches for crowded mandibularanterior teeth are currently employed: distalmovement of posterior teeth, lateral movement ofcanines, labial movement of incisors, interproximalenamel reduction, removal of premolars, removalof one or two incisors, and various combinationsof the above.Selecting the best treatmentis often difficult, and all guidelines do not apply toevery case. 5cording to Owen, 6 patients who are suitablefor single lower incisor extractions usually fit thefollowing diagnostic pattern: Class I molar relationship,moderately crowded lower incisors, mildor no crowding in the upper arch, acceptable softtissueprofile, minimal to moderate overbite andoverjet, no or minimal growth potential, and missinglateral incisors or peg shaped laterals.The aim of this case report was to assess thetreatment outcome and changes in dentofacialstructures especially mandibular incisor position after extraction of one single lower incisor.

Report of the cases:
A 22 years male from rangpur reported to a private dental practice office in Dhaka with the chief complain of irregularities in his teeth (specially in the lower anterior region) and gradual discoloration and decay of incisal edge of that particular lower anterior teeth over last two years.He reported that a local dentist in rangpur prescribes him scealing and polishing of that tooth to correct the discoloration, however he could not remember any history of trauma to that tooth.With a routine intraoral periapical radiograph (IOPA) of that tooth shows so evidence of periapical lesion or widening of periapical membrane space of that tooth.Pulp vitality test with electric pulp tester shows response higher electric level on that tooth compare to neighboring teeth, which indicate that the tooth is going to be non-vital.
On extra oral examinations patients having normal straight profile, which clearly does not indicated for extraction of teeth to manage this case.Cause extraction of teeth in such case will depress the upper and lower anterior alveolar base resulting a plate dish shape profile on post treatment appearances.No history of trauma to the teeth or tempero-mandibular joint, known medical history was reported.On introral examinations class I molar and class I canine relationship were noticed, however incisor relationship was edge to edge to bight with reduced overjet and over bite.Crowding on lower anterior arch was noticed.On routine radiographic examination with oral panoramic radiograph (OPG), and lateral cephalometric radiograph no sign of underlying bony pathology were noted with all periodontally healthy standing tooth, without any absence or missing tooth.On lateral cephalometric radiograph SNA, SNB, and ANB angle were recorded within its normal limit.This concluded this case a class I malocclusion with crowding on lower anterior segment.The treatment goal was set to correct the anterior crowding without changing the face profile, the SNA and SNB angle.To perform this clinically additional space is required to eliminate the crowding.Reproximation or disking of lower anterior teeth could be an option for that, however the arch perimeter and total anterior tooth material of lower jaw conclude that almost 3mm space is required.Extraction of any premolar in any side of the arch could affect the post treatment facial appearance; moreover unilateral premolar extraction could result the midline shift.So extraction of a mandibular incisor was plane for that.The challenge of extracting mandibular incisor is that it could reduce the SNB angle ultimately increasing the ANB angle that ultimately increases the chances of developing a deep bite.The treatment goal was set to correct the anterior crowding without changing the face profile, the SNA and SNB angle.To perform this clinically additional space is required to eliminate the crowding.Re-proximation or disking of lower anterior teeth could be an option for that, however the arch perimeter and total anterior tooth material of lower jaw conclude that almost 3mm space is required.Extraction of any premolar in any side of the arch could affect the post treatment facial appearance; moreover unilateral premolar extraction could result the midline shift.So extraction of a mandibular incisor was plane for that.The challenge of extracting mandibular incisor is that it could reduce the SNB angle ultimately increasing the ANB angle that ultimately increases the chances of developing a deep bite.In our cases the crowded incisor will need the extraction space for their leveling that ultimately maintain the SNB and ANB angle in its original position.With fixed orthodontic slandered edgewise bracket of 0.018× 0.025 slot and loop mechanics and proper torque in upper anterior teeth the class I relationship was maintained after finishing.Extraction of mandibular left central incisor tooth was done on to gain space for leveling the other incisor in a arch shape.That ultimately maintain the Class I incisor relationship with opposite arch teeth while retracting the upper anterior teeth.After retention phage bonded lingual retainer was placed with 'flexible spiral wire' of 0.012 millimeter (by OROMCO) that was placed by 'Super Bond C&B' (by Sun Medical Con.Japan).Over a two year post treatment patient found satisfied with his smile and occlusion and reveal good periodontal condition on the radiological follow-up in 2012.

Discussions:
The Class I molar and canine relationship wereestablished with satisfactory interdigitation of posteriorteeth.The negative overjet was transformed into a positive overjet, and theoverbite was improved.The upper and lower archlength deficiencies was eliminated and the toothsizediscrepancy was managed successfully.Themandibular dental midline was become the centerof the remaining lower central incisor.The dentitionand the periodontal tissues remained healthyduring treatment.Unaesthetic loss of the interdentalpapillae between the lower central incisorswas occurred as an unwanted sideeffect.Post-treatment radiographs showed that minimalroot resorption had occurred during treatmentand that root parallelism was satisfactory.Cephalometric evaluation revealed that no significantchanges were occurred except the increasingof the overbite.The lower and the upper incisorswere retroclined slightly, and the interincisal anglewas decreased.Lower cast analysis showed thatthere was no change in the arch length, the intercaninewidth was decreased, and interpremolarand intermolar widths were increased.A class I malocclusion with a significant mandibular tooth-size excess can frequently be treatedby extracting one mandibular incisor in the literature. 5A mandibular tooth-size excess greaterthan 1.6 mm, as determined by the Bolton analysis, 4 is considered significant and can typically behandled in 1 of 3 ways: interproximal reduction,extraction, restoration.Extraction of one mandibularincisor is generally done in patients withBolton discrepancies greater than 2.0 mm.Thedecision to extract should be supported by initialrecords, diagnostic wax setup, and clinical experience.Additional information, such as Boltonanalysis, shape of maxillary incisor crowns, andamount of interproximal enamel is also important. 7Reidel 8 has suggested that in patients with severelycrowded mandibular arches, the removalof one or more mandibular incisor(s) is the onlylogical alternative which may allow for increasedstability of the mandibular anterior region withoutcontinuous retention. 9In this case, we believedthat treatment results would be stable because ofthe fact that inter-canine width was decreased, andthe lower incisors were not protruded

Conclusions:
One single mandibular incisor extraction canbe an effective treatment choice for the appropriatemalocclusion with a Bolton discrepancy.However,several factors must be considered beforemaking the final treatment decision.In addition,evaluation of a diagnostic wax set-up will allowthe orthodontist to predict the success of the proposedtreatment plan

Figure 1 :Figure 2 :
Figure 1: Extra-oral photograph shows pretreatment smile of the patients(A), post treatment smile (B), pretreatment profile of the patients.The inter incisal gap showing in the pretreatment photograph (A) is eliminate after treatment (B).