Bilateral congenital absence of maxillary lateral incisors: a craniofacial and dental cast analysis

Skeletal and dentoalveolar characteristics of maxillary lateral incisor agenesis patients: a comparative cross-sectional study

BACKGROUND

The aim of the study was to evaluate the cephalometric and dentoalveolar characteristics of maxillary lateral incisor agenesis patients, and to compare the findings to a matched control group without tooth agenesis, excluding third molars, from the same population.

METHODS

The pre-orthodontic records of 72 non-growing patients, who were treated at the Orthodontic Department, Faculty of Dentistry, Alexandria University, were used to address the aim of this retrospective study. Patients having unilateral or bilateral maxillary lateral incisor agenesis, with no history of previous orthodontic treatment, congenital craniofacial malformations, facial trauma, or surgeries were divided into two test groups based on the pattern of maxillary lateral incisors agenesis (group I: unilateral (UMLIA), group II: bilateral (BMLIA)). A control group (group III (CTRL)) having a complete set of permanent dentition (excluding third molars), and having no dental anomalies was age-matched with the test groups. Measurements were performed on the pre-orthodontic lateral cephalometric radiographs and the pre-orthodontic digital dental casts. The measured variables were compared between the groups using one-way ANOVA and Kruskal Wallis tests according to the normality of the variable. In case of significant results, both tests were followed by multiple pairwise comparisons using Bonferroni adjusted significance level. Significance level was set at P < 0.05.

RESULTS

BMLIA group showed a smaller SNA angle and maxillary length, a more negative ANB angle and Wits appraisal, and a larger Maxillo-mandibular differential than UMLIA and/or CTRL group. The dental and soft tissue cephalometric measurements did not show any significant differences between the groups. Dentoalveolar cast measurements showed that BMLIA patients presented with significantly smaller maxillary inter-canine width than UMLIA and CTRL patients.

CONCLUSIONS

Cephalometric analysis has shown that subjects with BMLIA have a statistically significant reduced ANB and maxillary length. Tooth eruption may play a role in the development of the maxillary arch.

Comparison of craniofacial morphology in individuals with and without hypodontia with a special focus on the number of congenitally missing teeth

Background

Hypodontia might negatively affect dental function and esthetics, what might affect patients' self-esteem, communication behavior, professional performance and thus quality of life. The aim of this study was to estimate the influence of number of congenital missing teeth on dentofacial features.

Methods

Lateral cephalograms of 60 individuals with hypodontia (study group) and 40 individuals without hypodontia (control group) were analyzed. Patients in the study group were divided into two subgroups according to the number of missing teeth (group A with hypodontia 1 to 4 teeth and group B with hypodontia 5 or more teeth). Cephalometric data were compared among the study and control groups and statistically analyzed.

Results

The results in the present study revealed a significantly shorter and more retrognathic maxilla, more prognathic chin position, more retruded incisors in both jaws, large interincisal angle, straighter facial convexity as well as more retruded upper and lower lips in the group B compared with the control group. In the group A only chin position was significantly more prognathic compared with the control group.

Conclusions

According to the results of present study impact of hypodontia on the craniofacial morphology and consequently on facial esthetics was found statistically significantly greater in patients with 5 or more congenitally missing teeth.

Multidisciplinary management of congenitally missing lateral incisors: A minimally invasive approach

The following case report demonstrates how a multidisciplinary team approach can be utilized successfully for the minimally invasive esthetic treatment of congenitally missing maxillary lateral incisors through space closure and canine re-anatomization.

Morphometric evaluation of cranial base and sella turcica in patients with bilateral agenesis of maxillary lateral incisors

The aim of this paper is to evaluate the dimensions and morphology of cranial base and sella turcica in patients with bilateral agenesis of maxillary lateral incisors (BMLI). This retrospective study was conducted on lateral cephalometric radiographs of 34 female patients with BMLI (17.69 ± 2.96 years) and 34 female patients with complete dentation and skeletal Class 1 relationship serving as a control group (17.22 ± 2.2 years). Basicranial and maxillomandibular variables together with linear dimensions and morphology of sella turcica were evaluated. Differences between groups were analyzed by Student's t test for parametric variables and Mann-Whitney U test for nonparametric variables. Chi-square test followed by post hoc test with Bonferroni correction was used for categoric variables (p < 0.05). When compared to control group, N-S-Se angle was less negative, dimensions between Ba-Se, N-Ba, and N-Ar were larger, and SNA angle was smaller in BMLI group. There were no significant differences between groups regarding the linear dimensions of sella turcica. However, variations in sella turcica morphology were more frequent in BMLI group (n = 17; 50%) when compared to control group (n = 2; 5.8%). The most common morphologic variations in BMLI group were oblique anterior wall (20.6%) and irregularity (notching) in the posterior part of sella turcica (14.7%). The present study showed a statistically significant relationship between the presence of BMLI with some craniofacial parameters and morphological variations of sella turcica. This information may be useful as an additional and early diagnostic tool for BMLI and to highlight the possible links to its development.

The influence of mild versus severe hypodontia on facial soft tissues? A three-dimensional optical laser scanning-based cohort study

OBJECTIVE

To determine whether there are differences in the facial soft tissue morphology between participants with mild (up to two) or severe (six or more) hypodontia.

DESIGN AND SETTING

A prospective hospital-based cohort study.

PARTICIPANTS AND METHODS

Ninety-two participants, aged 11-16 years, with confirmed hypodontia were recruited. Participants were sub-grouped based on the severity (mild, two or less and severe, six or more) and distribution of the missing teeth and age. They underwent a three-dimensional (3D) optical surface scan of the facial soft tissues. Facial surface scans were compared quantitatively, applying landmark measurements and surface-based analysis.

RESULTS

In total, 92 participants, with an equal distribution between the mild (n=46) and severe (n=46) categories, were recruited. Patients with severe hypodontia displayed a reduced alar base, lower facial height, nasolabial angle (P = 0.02) and transgonial width (P < 0.001) compared to those with milder hypodontia. Furthermore, significant differences were observed between mild-male and severe-female groups regarding alar base, lower anterior face height and transgonial width and between mild-male and mild-female groups regarding nasolabial angle and transgonial width.

CONCLUSION

Significant reductions were seen in the 3D soft tissue morphology of participants with severe hypodontia, in terms of the nasolabial angle, lower facial height, alar base and transgonial widths, emphasising the importance of using facial scanning as a relatively simple non-invasive method of assessment.

Relationships between skeletal morphology and patterns of bilateral agenesis of third molars in Japanese orthodontic patients

The aim of this study was to reveal the correlations between bilateral agenesis of third molars (M3s) and skeletal morphology in Japanese male and female orthodontic patients. Sixty patients (30 males, 30 females), with bilateral agenesis of maxillary M3s and without agenesis of mandibular M3s (group U), and 60 patients (30 males, 30 females), with bilateral agenesis of mandibular M3s and without agenesis of maxillary M3s (group L), were selected as agenesis groups. Additionally, 60 patients (30 males, 30 females) with all four M3s were selected as the control group (group C). Patients in these three groups had no agenesis of teeth other than M3s. Lateral cephalograms of each patient were used to evaluate skeletal morphology of the maxilla and mandible. Two-way analysis of variance was used for statistical comparisons. Groups U and L had significantly smaller maxillary length and area than group C. Group U exhibited a significantly smaller lower facial height than group C. Males showed significantly larger maxillary length; total mandibular and mandibular body length; mandibular ramus height; SNB angle; maxillary area; and mandibular symphysis, corpus and ramus areas than females. Females had significantly larger lower facial height, gonial angle and ANB angle than males. Smaller maxillary length and area and lower facial height should be considered in planning orthodontic treatment for patients with bilateral agenesis of maxillary and mandibular M3s.

Canine substitution of congenitally missing maxillary lateral incisors in Class I and Class III malocclusions by using skeletal anchorage

INTRODUCTION

This prospective cohort study aimed to evaluate canine substitution supported by skeletal anchorage as a viable treatment protocol for patients with maxillary lateral incisor agenesis (MLIA) and skeletal Class I or Class III.

METHODS

Patients (n = 30) who met the following criteria were recruited: (1) bilateral MLIA or unilateral MLIA with a riziform contralateral incisor with a planned extraction; (2) skeletal Class I or Class III; and (3) dentoalveolar discrepancy in the mandible <5 mm. The archwire sequence routine was administered, combined with a rapid palatal expander, temporary intraoral skeletal anchorage device, and intermaxillary traction with Class III elastics. The results of the cephalometric analyses, peer assessment rating indexes, and the patient's smile self-evaluation using the visual analog scale were compared between initial and final treatments.

RESULTS

This study indicated that closing the space in patients with Class I or Class III malocclusion by using temporary intraoral skeletal anchorage devices in the mandible, along with Class III elastics, yielded satisfactory outcomes. Proper occlusion was established by mesialization of the maxillary teeth and correction of the intermaxillary discrepancy, thereby yielding beneficial and significant cephalometric changes after the treatment. The soft tissue profile was maintained when it was harmonious before the treatment and improved posttreatment in patients in whom the profile was initially inharmonious. All occlusions improved, as evidenced by the peer assessment rating index. Smile esthetics were also enhanced after orthodontic treatment for all patients.

CONCLUSIONS

Canine substitution may be safely offered to patients with Class I and Class III skeletal pattern and MLIA.

Examination of craniofacial morphology in Japanese patients with congenitally missing teeth: a cross-sectional study

Background

The purpose of this cross-sectional study was to investigate the effects of congenitally missing teeth on craniofacial morphology and to characterize the features of maxillofacial morphology of oligodontia patients associated with individual skeletal maturity by assessment with the cervical vertebrae maturation (CVM) method.

Methods

A total of 106 non-syndromic Japanese patients with congenitally missing teeth (except for third molars) were selected and categorized into two groups according to the severity of congenitally missing teeth (hypodontia group, 1–5 missing teeth [n = 56]; oligodontia group, ≥ 6 missing teeth [n = 50]). A control group included orthodontic patients without either skeletal disharmony or congenitally missing teeth (n = 63). Subjects in oligodontia and control groups were further categorized into two subgroups on the basis of cervical stage (CS): stage I (CS2 or 3; n = 27 and n = 31, respectively) and stage II (CS4 or above; n = 23 and n = 32, respectively). Lateral cephalograms were analyzed by using eight angular and eight linear measurements. Z-scores were formulated on the basis of age and sex and were matched to the Japanese norm. Tukey tests and t tests were performed.

Results

Compared with the control group, the hypodontia group had significantly smaller U1 to FH plane angle and A-B plane angle; U1-L1 was significantly larger. The oligodontia group had significantly smaller ANS-Me, L1 to mandibular plane angle, and Ptm-A; U1-L1 was significantly larger. At stage I, the oligodontia group had significantly smaller ANS-Me, gonial angle, and ANS-U1. At stage II, the oligodontia group had significantly smaller U1 to FH plane angle, L1 to mandibular plane angle, Ptm-A, and Go-Pog; it also had significantly larger U1-L1.

Conclusions

The present study suggested that skeletal patterns differ along with the number of congenitally missing teeth and that, in oligodontia patients, skeletal patterns differ before and after growth peak. It is important to consider the skeletal characteristics of tooth agenesis patients when designing a treatment plan.

Association between severity of hypodontia and cephalometric skeletal patterns: a retrospective study

Objective

To assess if severity of hypodontia is related to a specific skeletal pattern.

Study design

Lateral cephalometric radiographs and dental panoramic tomographs of 182 hypodontia patients were analysed. The severity of hypodontia was recorded and the sample was divided into groups with mild (n = 71), moderate (n = 56) and severe (n = 55) hypodontia. According to ethnicity, the sample was further subdivided into White Caucasians, African-British, and Arabian/Indian subgroups. Cephalometric measurements were used to quantify the skeletal discrepancy and vertical facial dimensions. Mean and standard deviation for each group were obtained for comparison and an analysis of variance (ANOVA) was carried out to assess the level of significance between the means of the readings in different severity groups.

Results

In the white Caucasian group, increased severity of hypodontia, was related to a retrusive maxilla with concomitant reduction of A point, Nasion, B point (ANB), reduced mandibular plane angle and anterior lower facial height (P value: 0.0935-0.9371). For the Black-British and Arabian/Indian groups' findings were inconsistent, with no specific pattern as the number of missing teeth increased.

Conclusion

The white Caucasian group followed a pattern that has previously been reported in other studies. For Black-British and Arabian/Indian groups' findings were inconsistent and no specific pattern emerged for different degrees of hypodontia.

Association between skeletal morphology and agenesis of all four third molars in Japanese orthodontic patients

The purpose of this study was to clarify differences in skeletal morphologies between male and female orthodontic patients with and without agenesis of all four third molars. A total of 64 patients (32 males and 32 females) with agenesis of all four third molars without agenesis of other teeth were selected as the third molars agenesis group (group 1). In addition, 64 patients (32 males and 32 females) with all these teeth were selected as controls (group 2). Lateral cephalograms taken between the ages of 14 and 30 years were used to compare skeletal morphology between groups 1 and 2 and between sexes. Maxillary length (P < 0.001), lower facial height (P < 0.05), gonial angle (P < 0.001) and mandibular plane angle (P < 0.001) were significantly smaller in group 1 than in group 2. Irrespective of the presence or absence of all four third molars, males had significantly smaller lower facial height (P < 0.01) and mandibular plane angle (P < 0.001) and significantly greater total mandibular length (P < 0.001), mandibular body length (P < 0.001) and mandibular ramus height (P < 0.001) than females. Japanese orthodontic patients with agenesis of all four third molars had significantly small maxillary length, lower facial height, gonial angle and mandibular plane angle.

Evaluation of the skeletal and dental effects in orthodontic patients with maxillary lateral incisor agenesis

OBJECTIVE

The purpose of this study was to evaluate the transverse dimension of the dentoalveolar and skeletal widths in both unilateral (UMLIA) and bilateral (BMLIA) maxillary lateral incisor agenesis groups.

MATERIALS AND METHODS

The study sample consisted of 59 patients (34 females and 25 males) divided into three groups as UMLIA group (16 patients; 14.94 ± 1.37 years), BMLIA group (21 patients; 14.46 ± 1.53 years) and control group (22 patients; 15.28 ± 1.70 years) without tooth agenesis. Transversal measurements (maxillary and mandibular intercanine, interpremolar, intermolar, intercanine alveolar, interpremolar alveolar, intermolar alveolar widths) were done on dental casts. Craniofacial skeletal measurements were done with posteroanterior cephalometric radiographs. Statistical testing was performed with the one-way variance analysis, Kruskal-Wallis and post hoc tests.

RESULTS

UMLIA and BMLIA groups had statistically significantly narrower skeletal apical base of the maxilla, maxillary intercanine and intercanine alveolar widths compared with the control group (P < .05). Moreover, UMLIA and BMLIA groups had statistically significantly similar dental, alveolar and skeletal features (P > .05).

CONCLUSIONS

The UMLIA and BMLIA groups showed statistically significantly smaller values for maxillary intercanine, maxillary intercanine alveolar and skeletal maxillary widths compared with the control group.

CLINICAL SIGNIFICANCE

This study provides information the transverse dimension of the dental, alveolar and skeletal widths with maxillary lateral incisor agenesis patients. Knowledge of transverse dimension of the dental, alveolar and skeletal widths with maxillary lateral incisor agenesis patients is important for diagnosis and treatment planning.

Tooth Size in Patients with Mild, Moderate and Severe Hypodontia and a Control Group

Objectives:

To compare tooth size between subjects with mild, moderate and severe hypodontia and a control group.

Material and Methods:

The study comprised 120 patients with hypodontia divided into three groups of 40 mild (≤2 teeth congenitally missing), 40 moderate (3-5 teeth congenitally missing) and 40 severe (≥6 teeth congenitally missing) hypodontia; and 40 age and sex matched controls. Tooth size was recorded by measuring the mesiodistal and buccolingual dimensions of all fully erupted teeth on study models using digital callipers and compared between all hypodontia and control groups using Two-way ANOVA and Post Hoc Tests of subgroup comparison.

Results:

Two-way ANOVA revealed patients with hypodontia had significantly smaller mesiodistal and buccolingual tooth dimensions compared with controls (p<0.05). Furthermore patients with more severe hypodontia demonstrated significantly smaller tooth dimensions than those in the mild and moderate hypodontia subgroups (p<0.05). The most affected tooth in terms of tooth size reduction was the maxillary lateral incisor and the least affected tooth was the mandibular first molar.

Conclusion:

Patients with hypodontia have smaller tooth dimensions than control. Tooth size appears to be affected by the degree of hypodontia, with severe hypodontia having a greater effect on tooth size reduction. The findings of this study may contribute to understanding the aetiology of hypodontia and aid the multidisciplinary management of this complex condition.

Prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population

OBJECTIVES

This study was aimed to investigate the prevalence of maxillary lateral incisor agenesis and associated skeletal characteristics in an orthodontic patient population.

MATERIALS AND METHODS

The records of the 1066 patients seeking orthodontic treatment were screened for maxillary lateral incisor agenesis (MLIA). The following data were recorded for each subject: age; gender; unilateral or bilateral agenesis of MLI and side. The lateral cephalogram of each subject with MLIA was digitally traced. The data were compared to age-matched control orthodontic patients with skeletal Class I.

RESULTS

The prevalence of maxillary lateral incisor agenesis was 4.9% (52 patients) in which 63.5% were females. There was a significant difference between MLIA patients and controls in sagittal relationships (ANB, Wits, AB plane, angle of convexity and Co-A/Co-Gn differential analyses) p < 0.05.

CONCLUSIONS

Patients with maxillary lateral incisor agenesis showed a significant tendency for skeletal Class III compared with the Class I control. This could be attributed to maxillary hypoplasia/retrognathia.

Tooth agenesis and craniofacial morphology in pre-orthodontic children with and without morphological deviations in the upper cervical spine

AIM: To analyze differences in prevalence and pattern of tooth agenesis and craniofacial morphology between non syndromic children with tooth agenesis with and without upper cervical spine morphological deviations and to analyze associations between craniofacial morphology and tooth agenesis in the two groups together.

METHODS: One hundred and twenty-six pre-orthodontic children with tooth agenesis were divided into two groups with (19 children, mean age 11.9) and without (107 children, mean age 11.4) upper spine morphological deviations. Visual assessment of upper spine morphology and measurements of craniofacial morphology were performed on lateral cephalograms. Tooth agenesis was evaluated from orthopantomograms.

RESULTS: No significant differences in tooth agenesis and craniofacial morphology were found between children with and without upper spine morphological deviations (2.2 ± 1.6 vs 1.94 ± 1.2, P > 0.05) but a tendency to a different tooth agenesis pattern were seen in children with morphological deviations in the upper spine. In the total group tooth agenesis was associated with the cranial base angle (n-s-ba, r = 0.23, P < 0.01), jaw angle (ML/RLar, r = 0.19, P < 0.05), mandibular inclination (NSL/ML, r = -0.21, P < 0.05), mandibular prognathia (s-n-pg, r = 0.25, P < 0.01), sagittal jaw relationship (ss-n-pg, r = -0.23, P < 0.5), overjet (r = -0.23, P < 0.05) and overbite (r = -0.25, P < 0.01).

CONCLUSION: Etiology of tooth agenesis in children with upper spine morphological deviations was discussed. The results may be valuable for the early diagnosis and treatment planning of non syndromic children with tooth agenesis.

The relationship between occlusal support and maxillary development: An animal study

Objective:

To test the hypothesis that maxillary development may be affected by occlusal support.

Materials and Methods:

The sample was composed by Wistar rats (5 weeks old) divided into three groups: Control (n = 10), extraction of mandibular molar teeth – left side (n = 10), extraction mandibular molar teeth – left and right sides (n = 10). The rats were sacrificed 8 weeks postextraction. Cone beam computed tomography scan images were taken for posterior measurement of maxillary length and width. Data were analyzed by one-way analysis of variance (Tukey test as post-hoc test).

Results:

Maxillary length was significantly shorter (P < 0.005) in both groups after tooth extraction. No difference was observed regarding maxillary width and body weight.

Conclusion:

Reduced occlusal support may impair the development of the maxilla in rats.

Congenitally missing teeth (hypodontia): A review of the literature concerning the etiology, prevalence, risk factors, patterns and treatment

Congenitally missing teeth (CMT), or as usually called hypodontia, is a highly prevalent and costly dental anomaly. Besides an unfavorable appearance, patients with missing teeth may suffer from malocclusion, periodontal damage, insufficient alveolar bone growth, reduced chewing ability, inarticulate pronunciation and other problems. Treatment might be usually expensive and multidisciplinary. This highly frequent and yet expensive anomaly is of interest to numerous clinical, basic science and public health fields such as orthodontics, pediatric dentistry, prosthodontics, periodontics, maxillofacial surgery, anatomy, anthropology and even the insurance industry. This essay reviews the findings on the etiology, prevalence, risk factors, occurrence patterns, skeletal changes and treatments of congenitally missing teeth. It seems that CMT usually appears in females and in the permanent dentition. It is not conclusive whether it tends to occur more in the maxilla or mandible and also in the anterior versus posterior segments. It can accompany various complications and should be attended by expert teams as soon as possible.

A multidisciplinary treatment of congenitally missing maxillary lateral incisors: a 14-year follow-up case report

Absence of the maxillary lateral incisor creates an aesthetic problem which can be managed in various ways. The condition requires careful treatment planning and consideration of the options and outcomes following either space closure or prosthetic replacement. Recent developments in restorative dentistry have warranted a re-evaluation of the approach to this clinical situation. Factors relating both to the patient and the teeth, including the presentation of malocclusion and the effect on the occlusion must be considered. The objective of this study was to describe the etiology, prevalence and alternative treatment modalities for dental agenesis and to present a clinical case of agenesis of the maxillary lateral incisors treated by the closure of excessive spaces and canine re-anatomization. A clinical case is presented to illustrate the interdisciplinary approach between orthodontics and restorative dentistry for improved esthetic results. In this report, the treatment of a girl with a Class II malocclusion of molars and canines with missing maxillary lateral incisors and convex facial profile is shown. Treatment was successfully achieved and included the space closure of the areas corresponding to the missing upper lateral incisors, through movement of the canines and the posterior teeth to mesial by fixed appliances as well as the canines transformation in the maxillary lateral incisors. This is a 14-year follow-up case report involving orthodontics and restorative dentistry in which pretreatment, posttreatment, and long-term follow-up records for the patient are presented.

Implant rehabilitation of canines in case of bilaterally missing maxillary lateral incisors

This article reports the successful treatment of a patient with a malocclusion and missing maxillary lateral incisors with an unusual implant-prosthetic rehabilitation in place of the canines. A man, 25 years 5 months of age, was referred by his general dentist with the chief complaint of retained maxillary deciduous canines. He had a skeletal Class I and an Angle Class I malocclusion with an open-bite tendency and prolonged retention of both deciduous canines. The malocclusion was treated with extraction of the maxillary deciduous canines, a fixed edgewise appliance, and implant-prosthesis rehabilitation in place of the canines. A functional and an esthetic occlusion was achieved.

Comparison of mesiodistal tooth widths in Caucasian, African and Japanese individuals with Brazilian ancestry and normal occlusion

OBJECTIVE: To observe the presence of sexual dimorphism and compare the mesiodistal width of the teeth in Caucasian, African and Japanese individuals with Brazilian ancestry not orthodontically treated and with normal occlusion. METHODS: One hundred pairs of dental casts were used. It was measured, from first molar to first molar in both arches, the teeth's mesiodistal widths, using a digital caliper. For the statistical analysis of results Kolmogorov-Smirnov, t test, ANOVA and Tukey's test (p < 0.05) were used. RESULTS: Sexual dimorphism occurred on the three evaluated groups, and the highest mesiodistal widths were found in males. There was statistically significant difference between racial groups in all evaluated teeth in males. However, in females, this same difference was found only on upper lateral incisor and first molar; and lower lateral incisor, canine, first premolar and first molar. CONCLUSION: Most of mesiodistal measures present particular characteristics in relation to gender, with higher values for males, and to race, with a tendency for African to present greater mesiodistal distance of the teeth, followed by Japanese and Caucasians, respectively, important for the correct diagnosis and orthodontic planning.

Evaluation of tooth size in patients with congenitally-missing teeth

Background and aims

Hypodontia is a common developmental abnormality of dentition. This study aimed to determine tooth width in patients affected with mild hypodontia and compare the results with a control group without tooth agenesis.

Materials and methods

The orthodontic records of 25 patients with congenital missing of one or two teeth (hypodontia group), and 25 subjects with full dentition (control group) were selected. The greatest mesiodistal width of each tooth was measured on the study models by a digital caliper. Tooth width measurements were compared between the groups using a student t-test at p < 0.05 of significance.

Results

Patients with hypodontia showed narrower teeth than the control subjects. The differences in tooth size between the two groups were statistically significant for the first and second premolars and first molar in the maxillary right and for the second premolar in the maxillary left quadrants (p < 0.05). In the lower arch, the first and second premolars and also first molar in both sides of hypodontia patients demonstrated significant reduction in tooth size compared to the control group (p < 0.05).

Conclusion

These findings suggest that patients with mild hypodontia have narrower teeth than normal subjects especially in posterior segments, which may have clinical implications during the orthodontic treatment process.

Effects of severity and location of nonsyndromic hypodontia on craniofacial morphology

OBJECTIVE

To evaluate the effects of severity and location of nonsyndromic hypodontia on craniofacial morphology.

MATERIALS AND METHODS

A total of 154 patients with at least two or more congenitally missing teeth were selected and divided into two groups (group I [mild]: patients with two to five missing teeth; group II [severe]: patients with six or more missing teeth). The patients with hypodontia were divided into three groups according to the location of missing teeth in the dental arches (anterior, posterior, and both anterior and posterior) and location of missing teeth between the jaws (maxilla, mandible, and both maxilla and mandible). Fifty Class I patients without any missing teeth served as the control group. Twenty-one measurements were performed on lateral cephalograms. Intergroup differences for the severity and location of hypodontia were analyzed using analysis of variance (ANOVA) and post-hoc Tukey tests.

RESULTS

Significant decreases were found in mandibular plane angles (P < .05), upper and lower incisor measurements (P < .05), anterior (P < .001) and posterior (P < .05) face heights, and ramus height (P < .01), as well as a significant increase in the soft tissue convexity angle (P < .05) among the hypodontia groups and control group. These differences were more excessive in the severe hypodontia group. Upper lip-E plane measurements were significantly longer in the mandible group than in the maxilla group (P < .01).

CONCLUSIONS

Patients with congenitally missing teeth have different craniofacial morphologies. The severity and location of missing teeth have a significant effect.

Orthodontic Considerations in Restorative Management of Hypodontia Patients With Endosseous Implants

The use of implant-supported restorations in patients with hypodontia remains challenging and requires a multistage treatment that begins in late mixed dentition and continues into late adolescence. The aim of this article is to review the role of orthodontics in endosseous implant rehabilitation of patients with hypodontia. The MEDLINE, Web of Science, Scopus, Cochrane databases, and necessary scientific textbooks were searched for relevant studies and reviews, and as far as possible, they were only included if they had been cited at least once in the literature. Dental implants are susceptible to overloading as the periodontal ligament is absent and the proprioceptive nerve endings are either lacking or very limited. Patients with hypodontia may present with skeletal features such as short and retrognathic maxilla, prognathic mandible, and shorter lower anterior facial height, and they sometimes need orthognathic correction as part of their overall treatment. Dental problems vary and include bimaxillary retroclination of incisors, spacing, centerline discrepancies, microdontia, hypoplastic enamels, ankylosis of the retained primary teeth, overeruptions, and volume deficiencies of alveolar ridges. The challenges mentioned, as well as bone volume deficiencies, compromise the successful placement of implants. Orthodontic strategies and techniques, such as uprighting mechanics, extrusion/intrusion, delayed space opening, and orthodontic implant site-switching, can be used to create, preserve, or augment the implant site. After orthodontic site development, the final planned position of the teeth should be maintained with a rigid bonded retainer; overlooking this stage may compromise the implant site and require orthodontic retreatment.

Investigation of the maxillary lateral incisor agenesis and associated dental anomalies in an orthodontic patient population

Objectives: The aim of this study was to investigate the prevalence of maxillary lateral incisor (MLI) agenesis and associated dental anomalies as well as skeletal patterns in an orthodontic population, and then to compare it with the prevalence of these anomalies in the general population. Study Design: The material of the present study included the records of the 3872 orthodontic patients. The followings were recorded for each subject with the agenesis of MLI: Age, sex, unilateral or bilateral absence, anterior-posterior skeletal relationship of the maxilla and mandible, and presence of associated dental anomalies. The occurrence of these anomalies was compared with data previously reported for the general populations. Results: Of the 3872 patients examined, 94 were found to have agenesis of the MLI, representing a prevalence of 2.4 per cent, with females being more frequently observed. The most commonly found associated anomalies were ectopic eruption of maxillary canines and reduced or peg- shaped contralateral incisor with the frequencies of 21.3 per cent and 20.2 per cent respectively. Conclusions: Patients with agenesis of MLI showed a significantly higher prevalence of skeletal Class III malocclusion compared with the general population. The prevalence of ectopic eruption, transposition, and transmigration of the maxillary canine and reduced or peg- shaped MLIs were significantly increased.

Key words:Hypodontia, missing laterals, associated dental anomalies.

Tooth sizes in nonsyndromic hypodontia patients

OBJECTIVE

To evaluate and compare the sizes of teeth in mild and severe hypodontia patients with those of healthy controls.

MATERIALS AND METHODS

Dental casts of 154 patients with two or more congenitally missing teeth were obtained. Patients were divided into two groups according to severity of hypodontia. Group I (mild) consisted of 118 patients with two to five missing teeth. Group II (severe) consisted of 36 patients with six or more missing teeth. In addition, a control group was included, which consisted of 50 patients who had an Angle Class I jaw relationship and no missing teeth. Mesiodistal and labiolingual dimensions of the teeth were measured with a digital caliper on dental casts. The independent-samples t-test was used to evaluate the effect of gender on measurements. Intergroup differences for mesiodistal and labiolingual dimensions were evaluated with analysis of variance and post hoc Tukey tests.

RESULTS

Statistically significant differences were found between girls and boys with hypodontia in the mesiodistal dimension of the mandibular first premolar and the labiolingual dimension of the mandibular lateral incisor (P < .01). Mesiodistal and labiolingual width measurements of the teeth of hypodontia patients showed statistically significant differences compared with the control group (P < .05). Most teeth showed significant dimensional reductions in severe hypodontia compared with mild hypodontia (P < .05).

CONCLUSIONS

The mesiodistal and labiolingual dimensions of teeth in both mild and severe hypodontia groups were smaller than those in control subjects. The reduction in size was more excessive in the severe hypodontia group. The teeth showing the greatest difference in tooth dimensions were the maxillary lateral incisor (in mesiodistal dimension) and the mandibular canine (labiolingual dimension).

Multidisciplinary approach in the rehabilitation of missing lateral incisors: a new trend in daily practice

This article reports the case of a patient with bilateral hypodontia of the maxillary lateral incisors who was dissatisfied with the outcome of initial orthodontic treatment, highlighting the importance of a multidisciplinary interaction among Restorative Dentistry, Orthodontics, and Implantology to achieve satisfactory esthetics and functional results.

Effects of hypodontia on craniofacial structures and mandibular growth pattern

Introduction

This study was performed to examine craniofacial structures in persons with hypodontia and to reveal any differences, that may occur, when agenetic teeth are only found in the maxilla, the mandible or in both jaws. The groups consistent of 50 children (33 girls, 17 boys) aged between 9 and 13.5 years were analyzed and assigned to three subgroups. Group 1 = upper jaw hypodontia. Group 2 = lower jaw hypodontia. Group 3 = hypodontia in both jaws.

Materials and methods

Eleven angular and three index measurements from lateral encephalographs and two linear measurements from dental blaster casts were calculated. All data was statistically analyzed, parameters with p < 5% were investigated for each subgroup respectively.

Results

In comparison with standards the study group showed bimaxillary retrognathism and a reduction of the lower anterior facial height. Moreover both overbite and overjet significantly increased. Other values laid within the normal ranges. Evaluating results of the subgroups, differences in the means of SNA, SNB and overjet between the groups were observed.

Analysis of the mandibular growth pattern revealed, that neither vertical nor horizontal patterns are dominant in hypodontia patients.

Conclusions

In certain dentofacial parameters differences between persons with hypodontia and such with full dentition exist. According to our findings agenetic teeth may have a negative influence on the saggital development of a jaw and the lower face and may be responsible for increased overbites. This should receive attention in orthodontic treatment of hypodontia patients.

Craniofacial repercussions in maxillary lateral incisors agenesis

OBJECTIVES

Assessment of the influence of maxillary lateral incisor agenesis (MLIA) on the facial morphogenesis.

METHODS

Evaluation of the skeletal dimensions of the upper maxilla and its incisor region. Analysis was performed among three groups: individuals with MLIA, its relatives and the normal population. Among these a comparison between adults and growing individuals was performed.

RESULTS

MLIA may interfere with the maxillary length and the anterosuperior facial height, negatively conditioning on its potential growth. MLIA was not correlated with changes of the palatine plane inclination, maxillary height nor with adjustment of the anterior nasal spine dimensions related to the Frankfurt plan or to the posterior nasal spine-Frankfurt plan during the observed development stage; the backward angle of the incisors in children with bilateral agenesis of lateral incisors appear to have been corrected in adulthood.

CONCLUSIONS

MLIA is associated with an upper maxilla shortening, and appear to interfere significantly with the anterior facial height, reducing its potential size.

A cephalometric study to investigate the skeletal relationships in patients with increasing severity of hypodontia

OBJECTIVES

To determine the skeletal relationships in patients with hypodontia and analyze the effects of severity and pattern.

MATERIALS AND METHODS

Pretreatment lateral cephalograms from 277 patients with hypodontia, categorized by the number of missing teeth as mild (1-2), moderate (3-5), or severe (> or =6), were digitized recording angular measurements and ratios and compared with published norms matched for age and gender. Pattern was determined as mandibular, maxillary, bimaxillary, bilateral, anterior, posterior, and anteroposterior. Linear regression models assessed relationships between number of missing teeth and cephalometric parameters, controlling for the pattern of hypodontia.

RESULTS

For every additional missing tooth, SNA, SNB, and ANB decreased 0.3 degrees , 0.1 degrees , and 0.2 degrees , respectively; this was clinically significant for >4, >10, and >5 missing teeth, respectively. Mandibular to cranial base ratio decreased 0.3% for every additional missing tooth; this was clinically significant for >10 missing teeth. The MMPA decreased 0.3 degrees for every additional missing tooth; this was clinically significant for >7 missing teeth. Percentage LAFH decreased 0.2% for every additional missing tooth; this was significant for >7 missing teeth. Jarabak ratio increased 0.2% for each additional missing tooth; this was clinically significant for >10 missing teeth. Anterior hypodontia significantly decreased most cephalometric parameters.

CONCLUSIONS

Patients with hypodontia demonstrated a tendency toward a Class III relationship, caused by decreased maxillary and mandibular angular prognathism and MnCB ratio, though the effect was greater on the maxilla than the mandible. Clinical significance was only associated with severe hypodontia. Vertically, there was a tendency toward decreased MMPA and %LAFH; this was clinically relevant only with severe hypodontia. Anterior hypodontia had a significant effect on skeletal relationship.

Dentofacial characteristics of patients with hypodontia

This study aims to identify distinctive dentofacial characteristics of hypodontia patients. For this purpose, 189 young hypodontia patients (cases) were divided into subgroups, based on criteria from literature. Normalised differences between cases and controls were calculated for various parameters of dentofacial form. Subsequently, cluster analysis was applied to disclose subsets of hypodontia patients with distinctive dentofacial features. The ANB angle, interincisal angle and lower anterior face height were consistently significantly different amongst the subsets. Four clusters of patients with an increasing number of missing teeth and distinctive dentofacial characteristics could be identified. Patients in cluster 1 display a high-angle facial pattern. Patients in clusters 2 and 3 exhibit markable dentoalveolar characteristics (a relatively small and a large interincisal angle, respectively). Patients in cluster 4 exhibited notable sagittal-skeletal discriminative features predominantly because of a retrognathic maxilla. The smallest nasolabial angle and lower anterior face height were seen in this cluster. It is concluded that the anterior-posterior relationship between the jaws, the interincisal angle and the lower anterior face height are discriminative parameters of dentofacial form in hypodontia patients. Patients with hypodontia can be clustered in four groups, each with distinctive vertical-skeletal, dentoalveolar and sagittal-skeletal characteristics. This categorisation of patients with hypodontia into meaningful groups may be useful for treatment planning, interdisciplinary communication and as a means of identifying groups of patients that qualify for reimbursement of costs. Other dental factors should be appreciated as well during restorative clinical decision making in patients with hypodontia.

Craniofacial profile in Southern Chinese with hypodontia

The association between craniofacial morphology and congenitally missing teeth is at present unclear. The aims of this study were to investigate whether hypodontia is associated with changes in the sagittal skeletal profile and to identify putative relationships between the skeletal profile and the severity of hypodontia. In a cross-sectional analytical study, the craniofacial structure and profile based on two-dimensional lateral cephalograms of Southern Chinese hypodontia patients (n = 49, 24 males, 25 females, mean age 16.4 years) and a comparison group without hypodontia (n = 41, 15 males, 26 females, mean age 16.7 years) were compared. The hypodontia patients were divided into three subgroups according to the severity of hypodontia (mild: < or =5, moderate: 6-9, and severe: > or =10 congenitally missing permanent teeth). All hypodontia patients had a significantly reduced mandibular plane, ANB, and face height compared with the control group (P < 0.05). A significant increase in chin thickness was also observed in the hypodontia patients (P < 0.05). As the severity of hypodontia increased from moderate to severe, a tendency to develop a retrognathic maxilla and a Class III skeletal relationship was noted in addition to the above features, making the already thick chin even more prominent. Statistically significant correlations (Pearson's correlation coefficient) were found between the number of missing teeth and SNA, NAFH, and ANB angles, the mandibular plane, chin thickness, and face height. In Southern Chinese subjects, hypodontia was associated with a shorter face, a flatter mandibular plane, a more pronounced chin, and a Class III skeletal profile. In severe hypodontia subjects, the maxilla was more retrognathic with a greater predilection to a Class III skeletal relationship.

Congenitally missing mandibular incisors and mandibular symphysis morphology

OBJECTIVE

To explore the association between congenital absence of permanent mandibular incisors and craniofacial and mandibular symphysis morphology in Japanese orthodontic patients.

MATERIALS AND METHODS

A total of 27 girls with one or two congenitally absent mandibular incisors (group M) were selected and divided into group 1M (16 girls with the absence of one incisor) and group 2M (11 girls with the absence of two incisors). In addition, 20 other Japanese girls without hypodontia and with little or no mandibular incisor crowding were enrolled as a control (group C). Using the lateral cephalogram of each subject, 17 angular, 8 linear, and 3 area measurements were made for evaluation of craniofacial and mandibular symphysis morphology. The cephalometric data thus obtained were statistically analyzed and compared between the groups.

RESULTS

A significantly greater retroclination of the retained mandibular incisors was found in group 1M than in group C. Groups 1M and M showed a significantly greater retroclination of mandibular alveolar bone than group C. Groups 2M and M exhibited a significantly smaller mandibular symphysis area than group C.

CONCLUSION

The retroclination of the mandibular incisors and alveolar bone and the reduced mandibular alveolar bone area should be taken into consideration in planning orthodontic treatment on patients with congenitally missing permanent mandibular incisors.

Treatment stability with the eruption guidance appliance

INTRODUCTION

Although the eruption guidance appliance has been used to correct Class II malocclusions for many years and its effects have been demonstrated, there is no study on the stability of the changes it produces. Therefore, the objective of this study was to investigate the long-term stability of cephalometric dentoskeletal and occlusal changes after eruption guidance appliance therapy.

METHODS

Thirty-nine patients were evaluated. Occlusal evaluations were made with the peer asseessment rating index, and anterior tooth irregularity was evaluated with the Little irregularity index. Cephalometric and occlusal data were obtained at pretreatment, posttreatment, and postretention. The data were analyzed by dependent 1-way analysis of variance (ANOVA) for comparison between the 3 stages of the experimental group, with the Newman-Keuls test as a second step. To compare the cephalometric experimental group changes with mean population changes, the t test was used.

RESULTS

Cephalometrically, in the postretention stage, overjet remained stable, overbite showed significant relapse, and molar relationship improved toward a Class I relationship. The peer asseessment rating index showed stability of the occlusion. The Little irregularity index demonstrated a statistically significant relapse of crowding in the postretention stage.

CONCLUSIONS

Cephalometrically, overjet and molar relationship were stable in the long term after treatment with the eruption guidance appliance; however, there was relapse of the overbite. Occlusally, correction of the malocclusion elevated by the peer assessment rating was stable. There was relapse of the anterior teeth crowding.

Hypodontia Patterns and Variations in Craniofacial Morphology in Japanese Orthodontic Patients

Objective: The purpose of this study was to explore the association of hypodontia patterns and variations in craniofacial morphology in Japanese orthodontic patients.

Materials and Methods: A total of 50 girls with hypodontia (the total group) were selected and categorized into anterior, posterior, and anterior-posterior groups according to the location of the congenitally missing teeth. By using the lateral cephalograms of each subject, 28 angular and 37 linear measurements were made. The cephalometric data were statistically analyzed and compared among the groups and with the Japanese cephalometric standards from 36 age-matched female subjects without hypodontia or malocclusion (the control group).

Results: Every hypodontia group showed shorter anterior and overall cranial base lengths, shorter maxillary length, greater retroclination and elongation of mandibular incisors, and a larger interincisal angle than the control group. The total and anterior-posterior groups especially exhibited a significantly more prognathic mandible, larger retroclination of maxillary incisors, and a more counterclockwise-rotated occlusal plane. Furthermore, these skeletal and dental deviations were more remarkable in the anterior-posterior group than in either the anterior or the posterior group. Anterior hypodontia exerted as much influence on craniofacial morphology as posterior hypodontia.

Conclusions: When orthodontic treatment is performed on patients with hypodontia, not only the number but also the distribution of missing teeth should be taken into consideration, though there was no significant difference in craniofacial morphology between anterior hypodontia and posterior hypodontia.

Determinação das medidas dentárias mésio-distais em indivíduos brasileiros leucodermas com oclusão normal

Em 60 modelos de gesso ortodônticos foram medidas as larguras mésio-distais dos dentes, de segundo molar a segundo molar, em ambos os arcos, utilizando um paquímetro digital modificado. Este trabalho teve como objetivos determinar o valor médio para a largura de cada dente e observar a presença de dimorfismo sexual, em indivíduos brasileiros leucodermas, com a média de idade de 16,03 anos (25 do gênero masculino e 35 do gênero feminino), não tratados ortodonticamente e portadores de oclusão normal, apresentando no mínimo quatro das seis chaves de oclusão, conforme descrito por Andrews. Os valores das médias individuais dos dentes estudados foram utilizados para a elaboração de uma tabela, correspondentes aos arcos superior e inferior.

Developmental absence of maxillary lateral incisors in the Portuguese population

The aim of this study was to evaluate the prevalence and clinical manifestation of developmental absence of maxillary permanent lateral incisors in the Portuguese population. The study group comprised 16 771 patients observed between 1993 and 2000 at the Faculty clinic. Two hundred and nineteen patients were found to have missing upper lateral incisors (131 females and 88 males, with ages ranging between 3 and 71 years), a prevalence of 1.3 per cent in this population. Absence of these teeth was bilateral in 44.7 per cent of the patients; of the unilateral cases, 33 per cent occurred on the right side and 21.9 per cent on the left side. In children under 8 years of age (n = 12), two (0.26 per cent) also had developmental absence of the primary lateral incisors, one unilateral and the other bilateral. Among the 121 subjects with unilateral developmental absence, the contralateral maxillary lateral incisor was found to be microdont in 57.1 per cent (right lateral 23 per cent, left lateral 34.1 per cent), suggesting the possibility that microdontia represents a variable expression of the same developmental defect that results in absence.

Outcome of orthodontic space closure with a missing maxillary central incisor

Orthodontic space closure is one of the treatment alternatives when a maxillary central incisor is missing. Because no systematic analysis of such treatment results is available, a sample of 20 consecutively treated patients was examined in a follow-up study. All patients had received orthodontic treatment with the objective of closing the space for the missing central incisor. Biologic features and the clinical appearance of the recontoured lateral incisor (test tooth) replacing the missing tooth were compared with the neighboring intact central incisor, which served as control tooth. The patients' opinions regarding the treatment and the result were recorded in a questionnaire. The position of the examined teeth and the appearance of the surrounding soft tissues were similar in the test and control teeth. However, in some patients (25%), certain aspects of the recontoured incisor crown (such as the width at the gingival margin) mismatched the appearance of the controls. A somewhat increased mobility and probing pocket depth on the mesial aspect was recorded for some test teeth. No obvious detrimental effects were observed on the radiographs. Most patients expressed satisfaction with the treatment result. It is concluded that orthodontic mesialization of the lateral incisor to replace a missing central incisor is a valid treatment modality, if the indications for such treatment are present and careful attention to detail in orthodontic and restorative treatment is exercised.

Tooth agenesis and craniofacial morphology in an orthodontic population

Previous reports have produced conflicting conclusions regarding the relationship among tooth agenesis, the congenital absence of teeth, and variations in craniofacial morphology. Traditional cephalometric assessment and computer-assisted morphometric analysis of jaw size were used to reexamine this relationship in a white orthodontic population. A positive diagnosis of tooth agenesis (including third molar determination) was made in 89 subjects of mixed age and sex who previously had orthodontic treatment but who were not determined to have a recognized syndrome or a craniofacial anomaly. Cephalograms for these subjects were compared with control data from subjects reported in Bolton Standards of Dentofacial Developmental Growth. Missing teeth and their locations were correlated with changes in selected linear and angular measurements of the Bolton cephalometric analysis. Area measurements of the jaw size of the subjects grouped by age were compared with Bolton cephalometric templates. Relatively little correlation was found between missing teeth and changes in cephalometric measurements. Where identified, a decreased maxillary jaw size and maxillary tooth agenesis were generally associated. Two-dimensional area measurements showed that most age groups had significant decreases in maxillary jaw size associated with tooth agenesis. Relatively few groups had significant changes in mandibular size associated with tooth agenesis.

An analysis of the skeletal relationships in a group of young people with hypodontia

The objective of this investigation was to examine the dentofacial features of a group of patients with hypodontia, in particular assessing whether cephalometric analysis confirmed the clinical assumption of a reduced lower face height, and to determine the relationship of these facial features with different numbers of missing teeth. It took the form of a cephalometric study, undertaken in a dedicated Dental Hospital clinic for patients with hypodontia. The study group comprised 59 patients seen on the Hypodontia Clinic: 32 females, 27 males, mean age 13.1+/-3.1 years (range 6-23 years). The average number of missing teeth was 7 (SD 5), ranging from 1 to 21. The mean SNA, SNB, and MMA angles were within normal limits, but there was a statistically significant reduction in the MMA when more than one tooth type was missing (P = 0.007) and the ANB angle decreased as the number of missing tooth types increased (P = 0.034). The mean values for the whole sample were within the normal range and did not demonstrate any feature specific to the group, but patients with more severe hypodontia showed tendencies to a Class III skeletal relationship and a reduced maxillary-mandibular planes angle.

Management of missing maxillary lateral incisors

BACKGROUND

Missing maxillary lateral incisors create an esthetic problem with specific orthodontic and prosthetic considerations. The purpose of this article is to describe treatment protocols and problems encountered in the management of this disorder.

CASE DESCRIPTION

The two common treatment options are orthodontic space opening for future restorations or orthodontic space closure using canines to replace the missing maxillary lateral incisors. The required amount of space opening and the various prosthetic options are discussed. The methods for reshaping canines in orthodontic space closure and building them up to simulate lateral incisors also are described. The indications, advantages and disadvantages of both treatment modalities are outlined to help clinicians make decisions in borderline situations.

CLINICAL IMPLICATIONS

Teamwork between the orthodontist, general practitioner and restorative dentist is important when analyzing factors related to individual patients and establishing overall treatment plans. This also will allow treatment modalities and the various options for replacing missing maxillary lateral incisors in space opening to be discussed between team members and the patient.

The orthodontic management of congenitally absent maxillary lateral incisors and second premolars: a case report

The orthodontic management of congenitally missing maxillary lateral incisors and second premolars is the subject of this case report. The primary orthodontic consideration was the maintenance of facial esthetics in a 12-year-old boy while consolidating, aligning, and coordinating the dental arches. The maxillary canines were orthodontically positioned in the lateral incisor spaces. The maxillary posterior teeth, including the deciduous second molars, were protracted to esthetic positions where they could function without interferences. The stability of the occlusion depends on the longevity of the maxillary deciduous second molar roots, which did not resorb during active tooth movement.

Dental agenesis in the Dariusleut Hutterite Brethren: comparisons to selected Caucasoid population surveys

We report the results of a study of the prevalence of nonsyndromic dental agenesis among a sample of 208 individuals (105 females, 103 males) between the ages of 15 and 29 years from a North American religious and genetic isolate, the Dariusleut Hutterites of Western Canada. Direct examination of dental casts, oral examination reports, dental treatment records, and a limited number of dental radiographs reveals congenital absence and/or obvious morphometric reduction of at least one tooth (excluding third molars) in 98 subjects (55 females, 43 males), yielding a prevalence estimate of approximately 47%. This estimate is nearly four times those reported for nonisolate Caucasoid populations of European descent and substantially higher than the elevated prevalences observed in several other isolated populations. Although the prevalence of dental agenesis in the Dariusleut is indeed high, neither the incidence of bilateral agenesis (exhibited at least once in 58% of affected dentitions), number of affected teeth per person (mean, 2.4), morphologic tooth classes affected, or combinations of tooth classes affected ostensibly distinguish them from other populations with similar geographic origins. We conclude that the dental agenesis observed in this North American genetic isolate does not represent a private polymorphism or rare developmental variant. Consequently, the results of further study in these Dariusleut Brethren will be directly relevant to critically testing as yet unresolved hypotheses for the mode of gene action and the relative contributions of hereditary and environmental factors to the reduction of tooth numbers in human dentitions.

Techniques for improving orthodontic results in the treatment of missing maxillary lateral incisors. A case report with literature review

We have presented a case report of the orthodontic treatment of a patient with congenitally missing lateral incisors and with skeletal and dental deep bite. Information was provided on methods to improve clinical orthodontic results. Different sections deal with (1) various diagnostic criteria for the best treatment approach, (2) variations in maxillary arch wire manipulation, (3) biomechanical considerations, (4) modifications of clinical crown by special procedures so that the canines resemble and function as lateral incisors, (5) functional considerations of the occlusion, and (6) details in finishing. Particular emphasis was placed on the use of a special design of closing loops for simultaneous space closure and intrusion of the anterior teeth. This article has discussed the principles of incisor and canine intrusion, and has demonstrated that the closing loops described are capable of intruding incisors with minimal side effects on the posterior teeth. It has also demonstrated how control of the mechanical variables dramatically increased the efficiency and effectiveness of intra- and extraoral forces in the treatment of malocclusion.