• The korean journal of orthodontics
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• v.25 no.5 s.52
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• pp.593-604
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• 1995

Mandibular incisor crowding is one of the most common features of malocclusion and is interesting characteristic in view of relapse and stability after orthodontic treatment. There are many potential factors in the etiology of lower anterior crowding. The tooth size variation is one of them, but biologic significance for the faciolingual width of the teeth has been overlooked. Peck and Peck reported that persons with ideal mandibular incisor alignment were shown to have incisor with smaller mesiodistal and larger faciolingual dimensions than persons with incisor crowding. On the basis of these findings they suggested MD/FL index as a clinical guideline for the assessment for lower incisor crowding. The present study was undertaken to examine the relationship between mandibular incisor crowding and mandibular incisor dimension, and determine their correlation with arch length discrepancy. 154 dental casts of people from 11 to 17 years of age were made, and were divided into normal group with irregularity index less than of 1, and crowding group with irregularity index greater than 1.The casts were measured and analyzed statistically. The results were as follows. 1. The mean mesiodistal width for mandibular incisor was larger in crowding group, and has significant difference in central inciosr measurement. There are no significant differences in the faciolingul width and MD/FL index. 2. Irregularity index has significant correlation coefficients with mesiodistal width and MD/FL index for mandibular incisor in crowding group, but no correlation with faciolingual width. It also has correlation with maxillary and mandibular arch length discrepancy, total tooth material, mandibular intercanine width, and mandibular inter first premolar width. 3. Upper and lower arch length discrepancy have significant correlation with mesiodistal width of mandibular incisor and overbite, but have no correlation with faciolingual width. Lower arch lenth discrepancy has significant correlation with MD/FL index for mandibular incisor and upper arch length discrepancy has correlation with MD/FL index for mandibular lateral incisor. 4. Significant differences were observed between normal and crowding group for the mandibular arch length discrepancy and overbite.

• Imaging Science in Dentistry
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• v.51 no.2
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• pp.155-165
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• 2021

Purpose: This study aimed to evaluate changes of the alveolar bone and interdental bone septum of the mandibular incisors through cone-beam computed tomography (CBCT) after orthodontic treatment of mandibular dental crowding without dental extraction. Materials and Methods: The sample consisted of 64 CBCT images(32 pre-treatment and 32 post-treatment) from 32 adult patients with class I malocclusion and an average age of 23.0±3.9 years. The width and height of the alveolar bone and interdental septum, the distance between the cementoenamel junction (CEJ) and the facial and lingual bone crests, and the inclination of the mandibular incisors were measured. Results: The distance between the CEJ and the marginal bone crest on the facial side increased significantly (P<0.05). An increased distance between the CEJ and the bone crest on the facial and lingual sides showed a correlation with the irregularity index (P<0.05); however, no significant association was observed with increasing mandibular incisor inclination (P>0.05). The change in the distance between the CEJ and the marginal bone crest on the facial side was correlated significantly with bone septum height(P<0.05). Conclusion: Bone dehiscence developed during the treatment of crowding without extraction only on the incisors' facial side. Increasing proclination of the mandibular incisor was not correlated with bone dehiscence. The degree of dental crowding assessed through the irregularity index was associated with the risk of developing bone dehiscence. The interdental septum reflected facial marginal bone loss in the mandibular incisors.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.547-552
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• 2001

Extracting mandibular incisors for orthodontic treatment may adversely affect the occlusion. However, when properly used, extraction of mandibular inciors is a selection for the correction of the malocclusion. Generally, treatment for crowding needs to select between nonextraction and four premolar extraction. Approaches for crowded mandibular incisors include distal movement of posterior teeth, lateral movement of canines, labial movement of incisors, interproximal enamel reduction, removal of premolars, removal of one or two incisors, and various combinations of the above. Extraction of incisors is used in case of crowding, anterior tooth size discrepancy, absent of maxillary lateral incisors, and ectopic eruption. But severe overjet. overbite, and space are the contraindication of it. A patient had severe crowding on upper anterior teeth, impacted upper left lateral incisor, palatal ectopic eruption of upper right incisor and severe crowding on lower anterior teeth. Lower lateral incisors are extracted for space availability and facial esthetics. We report the case of orthodontic treatment of upper and lower anterior crowding through extraction of lateral incisor.

• The korean journal of orthodontics
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• v.47 no.3
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• pp.176-185
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• 2017

Objective: To evaluate the relationship of gingival thickness (GT) and the width of keratinized gingiva (WKG) with different malocclusion groups and the level of crowding. Methods: A total of 187 periodontally healthy subjects (121 females and 66 males) who presented at the Faculty of Dentistry in $Y{\ddot{u}}z{\ddot{u}}nc{\ddot{u}}$ Yil University for orthodontic treatment were enrolled in the study. The individuals involved in the study were divided into three groups; Angle Class I malocclusion, Angle Class II malocclusion, and Angle Class III malocclusion. Each group was classified as mild, moderate, or severe according to the level of crowding. WKG was determined as the distance between the mucogingival junction and the free gingival margin. GT was determined by the transgingival probing technique. Factorial variance analysis and the Duncan multiple comparison test were employed to identify the extent to which a difference was apparent between the groups according to these parameters. Results: It was determined that teeth in the mandibular anterior region display the thin gingival biotype. WKG and GT were observed as being higher at the mandibular incisor teeth in the severe crowding group and at the mandibular canine teeth in the mild crowding group. The GT of the mandibular right central and lateral incisors was found to be thinner in the Angle Class III group. Conclusions: Within the limits of this study, the results demonstrate that, there is no significant relationship of WKG and the mean GT in the mandibular anterior region according to the Angle classification.

• The korean journal of orthodontics
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• v.50 no.1
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• pp.52-62
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• 2020

This case report presents the orthodontic treatment of a 25-year-old patient with skeletal Class II and severe maxillary arch crowding, moderate mandibular arch crowding, anterior crossbite, and a missing lower incisor. He was treated with molar distalization using a modified C-palatal plate and temporary anchorage devices to create sufficient space for retraction. The total treatment duration was 21 months. After treatment, his occlusion and smile esthetics showed significant improvement. The modified C-palatal plate represents a treatment modality that enhances the prospects of non-extraction treatment and reduces the need for extraction.

• The korean journal of orthodontics
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• v.47 no.1
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• pp.11-20
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• 2017

Objective: This randomized controlled trial aimed to compare the stability of mandibular arch orthodontic treatment outcomes between passive self-ligating and conventional systems during 6 months of retention. Methods: Forty-seven orthodontic patients with mild to moderate crowding malocclusions not requiring extraction were recruited based on inclusion criteria. Patients (mean age $21.58{\pm}2.94years$) were randomized into two groups to receive either passive self-ligating ($Damon^{(R)}$ 3MX, n = 23) or conventional system (Gemini MBT, n = 24) orthodontic treatment. Direct measurements of the final sample comprising 20 study models per group were performed using a digital caliper at the debonding stage, and 1 month, 3 months, and 6 months after debonding. Paired t-test, independent t-test, and non-parametric test were used for statistical analysis. Results: A significant increase (p < 0.01) in incisor irregularity was observed in both self-ligating and conventional system groups. A significant reduction (p < 0.01) in second interpremolar width was observed in both groups. Mandibular arch length decreased significantly (p = 0.001) in the conventional system group but not in the self-ligating system group. A similar pattern of stability was observed for intercanine width, first interpremolar width, intermolar width, and arch depth throughout the 6-month retention period after debonding. Comparison of incisor irregularity and arch dimension changes between self-ligating system and conventional system groups during the 6 months were non-significant. Conclusions: The stability of treatment outcomes for mild to moderate crowding malocclusions was similar between the self-ligating system and conventional system during the first 6 months of retention.

• The korean journal of orthodontics
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• v.44 no.5
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• pp.268-277
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• 2014

A Brazilian girl aged 14 years and 9 months presented with a chief complaint of protrusive teeth. She had a convex facial profile, extreme overjet, deep bite, lack of passive lip seal, acute nasolabial angle, and retrognathic mandible. Intraorally, she showed maxillary diastemas, slight mandibular incisor crowding, a small maxillary arch, 13-mm overjet, and 4-mm overbite. After the diagnosis of severe Angle Class II division 1 malocclusion, a mandibular protraction appliance was placed to correct the Class II relationships and multiloop edgewise archwires were used for finishing. Follow-up examinations revealed an improved facial profile, normal overjet and overbite, and good intercuspation. The patient was satisfied with her occlusion, smile, and facial appearance. The excellent results suggest that orthodontic camouflage by using a mandibular protraction appliance in combination with the multiloop edgewise archwire technique is an effective option for correcting Class II malocclusions in patients who refuse orthognathic surgery.

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.3
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• pp.507-512
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• 1999

In the mixed dentition, many children have mild crowding of anterior dentition on the mandibular arch and mesial tilting of mandibular molar. Lip bumper have been used to gain arch length for the alignment of mild to moderate crowded dental arches. As such, they may provide an alternative to extraction therapy. The claimed therapeutic effect of the lip bumper is bodily forward incisor movement, flaring of the lower incisors, and distal tipping of the molar. The dental changes can be attributed to removal of lip pressure on the lower anterior dentition and the distal forces exerted at the molar abutment. The purpose of this study is to show more easily method of treatment for mild anterior crowding of mandible.

• The korean journal of orthodontics
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• v.45 no.4
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• pp.190-197
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• 2015

Objective: The aim of the study was to analyze the prevalence and distribution of ectopic eruption of the permanent maxillary first molar (EEM) in individuals scheduled for orthodontic treatment and to investigate the association of EEM with dental characteristics, maxillary skeletal features, crowding, and other dental anomalies. Methods: A total of 1,317 individuals were included and randomly divided into two groups. The first 265 subjects were included as controls, while the remaining 1,052 subjects included the sample from which the final experimental EEM group was derived. The mesiodistal (M-D) crown width of the deciduous maxillary second molar and permanent maxillary first molar, maxillary arch length (A-PML), maxillomandibular transverse skeletal relationships (anterior and posterior transverse interarch discrepancies, ATID and PTID), maxillary and mandibular tooth crowding, and the presence of dental anomalies were recorded for each subject, and the statistical significance of differences in these parameters between the EEM and control groups was determined using independent sample t -tests. Chi-square tests were used to compare the prevalence of other dental anomalies between the two groups. Results: The prevalence of maxillary EEM was 2.5%. The M-D crown widths, ATID and PTID, and tooth crowding were significantly greater, while A-PML was significantly smaller, in the EEM group than in the control group. Only two subjects showed an association between EEM and maxillary lateral incisor anomalies, which included agenesis in one and microdontia in the other. Conclusions: EEM may be a risk factor for maxillary arch constriction and severe tooth crowding.

• The korean journal of orthodontics
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• v.26 no.1 s.54
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• pp.33-41
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• 1996

Retrostpective study of two groups of patients was conducted to evaluate the physiologic drift of the mandibular teeth following the extraction of four first premolars. The concept of physiologic drift, commonly referred to as 'driftodontics', following first premolar extractions has been gaining acceptance in the orthodontic community, the exact nature and amount of drift has not been adequately documented. There were also no guide lines as to when drift should be allowed to now. The purpose of this study was to quantify physiologic drift of the untreated mandibular dentition following extraction of the four first premolars during the early permanent and late permanent dentition stages. The early permanent dentition extraction sample(Group 1) included 26 Patients and the mean age at pretreatment was approximately 13.5 years. The observation period following extraction was approximately 6.96 months. The late permanent dentition extraction sample(Group 2) included 31 patients. The mean age at pretreatment was 21.3 years, followed by a observation period of 7.26 months. During the observation period, except for the extractions, no other mandibular therapy was rendered. Pre-and post-treatment lateral cephalograms and dental casts were analyzed. The obtained results were as follows 1. Group 2 showed marked changes in movements of the mandibular incisors and canines but minimal changes in molars. 2. The amount of changes in movements of the mandibular incisors and canines were significantly greater in Group 1 than in Group 2. The results showed no differences in rates of molar movements between groups. 3. Physiologic drift of the dentition produced desirable changes such as decreased Incisor Irregularity.