Effects of severity and location of nonsyndromic hypodontia on craniofacial morphology

Tooth agenesis: An overview of diagnosis, aetiology and management

Patients with one or more developmentally absent teeth are routinely encountered in dental practice. Tooth agenesis can be associated with significant functional, aesthetic and psycho-social problems. The present article provides an overview of the prevalence and aetiology of tooth agenesis, as well as the condition's clinical characteristics and management options with reference to the evidence base. A timely diagnosis can facilitate the appropriate planning and management which might not be straightforward, and patient care will likely require multi- and inter-disciplinary input. It is critical that dental care practitioners are aware of the clinical characteristics and management options for tooth agenesis.

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.

Number of Teeth Is Related to Craniofacial Morphology in Humans

Simple Summary

In modern humans, congenital absence of one or more permanent teeth has a prevalence of 22.6% when considering the third molars and of 6.4% when not. Its high prevalence, in conjunction with evolutionary findings pinpointing to a steady reduction in teeth number, raises the question whether the congenital absence of teeth in modern humans is an evolutionary trend rather than an anomaly. Previous studies have shown that modern humans with less teeth also have smaller faces; however, the association between teeth number and craniofacial morphology remains unclear. Here, we show that less teeth are associated with a flatter profile and a decreased facial height. These findings support the claim of a broader relationship between number of teeth and overall craniofacial development and have evolutionary implications, since face reduction comprises also an evolutionary trend in humans.

Abstract

One of the most common dental anomalies in humans is the congenital absence of teeth, referred to as tooth agenesis. The association of tooth agenesis to craniofacial morphology has been previously investigated but remains unclear. We investigated this association by applying geometric morphometric methods in a large sample of modern humans. In line with previous studies, we report here that a reduced teeth number is linked to a less convex profile, as well as to a shorter face. The effects were similar for males and females; they increased as the severity of the tooth agenesis increased and remained unaltered by the inclusion of third molars and of allometry in the analysis. Furthermore, in cases with tooth agenesis only in the maxilla, there was no detectable effect in mandibular shape, whereas maxillary shape was affected independently of the location of missing teeth. The robustness of the present sample along with the shape analysis and the statistical approach applied, allowed for thorough testing of various contributing factors regarding the presence but also the magnitude of effects. The present findings suggest a relationship between number of teeth and overall craniofacial development and have evolutionary implications.

Evaluation of the effects of hypodontia on the morphology of craniofacial structures

OBJECTIVE

The study aimed to investigate the effects of hypodontia on the sagittal and vertical dimensions of the jaws, dentition and the related soft tissue.

MATERIALS AND METHODS

The hypodontia group included 111 patients whose growth was completed with one or more congenitally missing teeth (CMT). Sixty additional patients with skeletal and dental class I relationship, without CMT, and who completed growth, were included as the control group. The hypodontia group was divided into three subgroups according to the intermaxillary (maxillary or mandibular) location, intramaxillary (anterior or posterior) location and the severity of hypodontia (mild: 1-2 CMT or moderate: 3-6 CMT). Twenty-three measurements were performed on lateral cephalograms of the patients. The one-way and Kruskal-Wallis Analysis of Variance tests were used for the statistical analysis. The false discovery-rate analysis was applied for the multiple comparison adjustment.

RESULTS

No significant difference was found in the skeletal measurements between all hypodontia subgroups and the control (P > .05). Upper incisors were found to be retroclined in the anterior hypodontia group. The upper lip was found to be protruded in the mandibulary hypodontia group compared to the control (P < .05).

CONCLUSION

The mild-to-moderate hypodontia did not produce a significant skeletal effect. However, hypodontia can affect the incisors, especially when CMT is in the anterior region. Besides, the effects of severe hypodontia could not be evaluated due to the insufficient number of oligodontia patients.

Maxillofacial morphological characteristics in growing orthodontic patients with non-syndromic oligodontia

OBJECTIVE

Patients with oligodontia frequently show different types of malocclusions. However, how oligodontia affects the maxillofacial growth remains uncertain. This study aimed to investigate the maxillofacial morphological characteristics in growing patients with oligodontia.

SETTING AND SAMPLE POPULATION

The study subjects included 33 Japanese children with non-syndromic oligodontia (14 boys and 19 girls; mean age: 10.2 years) who visited the orthodontic clinic of Fukuoka Dental College Medical and Dental Hospital from 1999 to 2019.

MATERIALS AND METHODS

Cephalometric analyses were performed, and the variables measured in each subject were converted into Z scores in relation to the mean and standard deviation of the Japanese norms matched for growth stage. The one-sample t-test or Wilcoxon signed-rank test was performed to compare the mean scores in the patients with oligodontia with those of the Japanese norms.

RESULTS

Compared with the Japanese norms, patients with oligodontia showed a smaller convexity and larger A-B plane and SNB angles. The Frankfort-mandibular plane and gonial angles were smaller, whereas the height of the ramus was larger. The vertical height of the alveolar bone in the maxillary and mandibular incisors and molar areas was smaller in patients with oligodontia.

CONCLUSIONS

Patients with oligodontia showed Class III skeletal tendency with mandibular prognathism and flattened mandibular plane with a smaller gonial angle. These maxillofacial morphological features can be induced by a deficiency in the vertical growth of the alveolar bone in the maxillary and mandibular molar areas due to the lack of tooth germs.

Effect of Tooth Agenesis on Mandibular Morphology and Position

Congenital missing teeth (OMIM #106600) is the most common dental abnormality. The aim of the study was to evaluate the effects of tooth agenesis on the total mandibular length, length of the mandibular body and alveolar process, and the mandibular anteroposterior position. The material was obtained from the Department of Orthodontics, Medical University of Warsaw. The study group included 116 patients aged 9–18 years with a congenital absence of at least two permanent tooth buds in the maxilla and/or mandible (mean: 6.2 teeth missing/patient). All patients were Caucasians: 68 (59%) females and 48 (41%) males. The control group included 115 patients without tooth agenesis matched with the age and gender of the study group. A cephalometric analysis was performed, and it was focused on assessing anteroposterior mandibular measurements. This assessment was based on 17 measurements (12 linear and 5 angular). Statistical analysis of the cephalometric measurements between the study group and the control group showed significant changes regarding selected mandibular measurements. Tooth agenesis does not affect the total length of the mandible and the length of the mandibular body, but it might reduce the length of the mandibular arch length and result in a more retrusive mandibular position.

Missing and unerupted teeth in osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI) is a genetic disorder characterized by bone fragility and craniofacial and dental abnormalities such as congenitally missing teeth and teeth that failed to erupt which are believed to be doubled in OI patients than normal populations and were associated with low oral health quality of life. However, the etiology of these abnormalities remains unclear. To understand the factors influencing missing and unerupted teeth, we investigated their prevalence in a cohort of OI patients as a function of the clinical phenotype (OI type), the genetic variant type, the tooth type and the onset of bisphosphonate treatment.

METHOD

A total of 144 OI patients were recruited from The Shriners Hospital, Montreal, Canada, between 2016 and 2017. Patients were evaluated using intraoral photographs and panoramic radiographs. Missing teeth were evaluated in all patients, and unerupted teeth were assessed only in patients ≥15 years old (n = 82).

RESULTS

On average, each OI patient had 2.4 missing teeth and 0.8 unerupted teeth, and the most common missing and unerupted teeth were the premolars and the upper second molars, respectively. These phenomena were more prominent in OI type III and IV than in OI type I, and were not sex or age-related. Missing teeth were significantly more common in patients with C-propeptide variants than all other variants (p-value <0.05). Unerupted teeth were significantly more common in patients with α1 and α2 glycine variants or substitutions than in those with haploinsufficiency variants. Early-onset of bisphosphonate treatment would significantly increase the risk of unerupted teeth in patients with OI types III and IV (OR = 1.68, 95% CI (1.15-1.53)).

CONCLUSION

The prevalence of missing and unerupted teeth at the tooth type level in OI patients varies according to the nature of the collagen variants and the OI type. These findings highlight the role of collagen in tooth development and eruption.

Interdisciplinary management of nonsyndromic tooth agenesis in the digital age

BACKGROUND AND OVERVIEW

Tooth agenesis is the most common congenital condition affecting the oral cavity. This condition can involve single or multiple missing teeth. Severe forms of tooth agenesis are best managed by a team of specialists, as they can be daunting for a single provider.

CASE DESCRIPTION

As the goal of most patients is to replace missing teeth to improve cosmesis and function, a prosthodontist or restorative dentist plays a major role in the team's effort. Although diagnostic skills and careful planning are still the mainstay of this treatment, digital technology and modern materials can greatly facilitate implementation of the treatment plan. The authors present a case of a patient with nonsyndromic oligodontia who had a deficient occlusal vertical dimension that was treated by means of an interdisciplinary approach. The management included a combination of orthodontics, fixed and removable prosthodontics, and oral surgery.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

When treating patients with complex congenital tooth anomalies, the prosthodontist or restoring dentist is well positioned to take the lead and orchestrate treatment of the patient.

Is dental agenesis associated with craniofacial morphology pattern? A systematic review and meta-analysis

BACKGROUND/OBJECTIVE

Craniofacial discrepancies have been associated with congenital dental anomalies. The aim of this study was to determine if there is any scientific evidence in the literature regarding the association between dental agenesis and craniofacial morphology.

MATERIALS AND METHODS

A systematic review and meta-analysis following the PRISMA Statement were conducted and registered in PROSPERO database. A broad search was conducted on databases (PubMed, Virtual Health Library, Web of Science, and Scopus) and grey literature. Articles that were selected based on predetermined eligibility criteria were assessed for quality and risk of bias according to the guidelines described by Folkes and Fulton. Those articles with similarities were submitted to meta-analysis using the RevMan 5.3 program. The certainty of the evidence was tested using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation).

RESULTS

An electronic search of 975 articles resulted in 12 articles. These and four articles identified through manual search were eligible to be assessed for methodological quality and the risk of bias. Eleven articles presented moderate to high methodological quality. The included articles observed a reduced mandibular plane, a smaller maxilla and more differences with the increase in the severity of dental agenesis. Seven articles were included in the meta-analyses. Dental agenesis presented smaller SNA angle (P < 0.0001/CI -1.74 [-2.55, -0.92]) with moderate certainty of the evidence; and smaller ANB angle (P = 0.01/CI -0.80 [-1.44, -0.17]), with low certainty of the evidence.

CONCLUSIONS

This systematic review and meta-analysis demonstrated that dental agenesis may be associated with specific craniofacial morphology. Further studies are necessary due to the variation of the certainty of the evidence.

CONFLICT OF INTEREST

none declared.

REGISTRATION

PROSPERO (CRD42017055882).

Growth differences in patients with dental agenesis, how its location impacts facial morphology

Background/purpose

Non-formation of a tooth impacts the morphology of the alveolar bone, which may, in turn, generate an imbalance in facial growth. This retrospective case-control study aimed to determine whether observable differences exist in the facial growth of patients with dental agenesis relative to complete dentition controls.

Materials and methods

The sample comprised 75 patients with dental agenesis, and each case was paired with two controls of the same age and gender (n = 150). All patients were measured cephalometrically (31 variables), and both groups were compared with student's t- or Z-test (P < 0.05). Subsequently, ANOVA or Kruskal–Wallis tests (P < 0.05) were used to compare facial growth depending on the missing tooth's sagittal location in the dental arch (anterior or posterior agenesis); as well as its location in the affected bone (maxillary, mandibular, or both).

Results

Four measurements with significant differences were found, whereas ten were found in the sagittal location in the dental arch analysis. Regarding the affected bone, there were no affected variables.

Conclusion

it was found that patients with dental agenesis show differences in the sagittal growth of the upper jaw and in the position of the lower incisor. In the studied population, these changes are strongly influenced by the sagittal location of the missing tooth, while its location in the jaws does not affect facial growth.

Cervicovertebral anomalies and/or normal variants in patients with congenitally bilateral absent maxillary lateral incisors

OBJECTIVE

To determine whether there is a relationship between congenitally bilaterally absent maxillary lateral incisors (BAMLIs) and skeletal anomalies and/or normal variants.

MATERIALS AND METHODS

The records of 86 patients (62 girls, 24 boys; age 12-17 years) with congenitally BAMLIs and 86 patients (55 girls, 34 boys; age 13-18 years) without any dental or skeletal anomalies were collected and evaluated retrospectively. The study was based on the evaluation of lateral cephalometric and orthopantomographic radiographs. Posterior arch deficiency of the atlas bone (PADA); atlanto-occipital ligament calcification, known as "ponticulus posticus" (PP); and interclinoid ligament calcification, known as "sella turcica bridging" were recorded for each participant. Pearson χ2 and Fisher exact tests were used to evaluate and compare skeletal anomalies and/or normal variants between patients with BAMLIs and the control group.

RESULTS

The prevalence of cervicovertebral anomalies and/or normal variants seen in the lateral cephalometric radiographs was higher in patients with BAMLI than in the control group. The prevalence of PP was lower and that of PADA was higher in patients with BAMLIs than in the control group (P < .05).

CONCLUSION

The prevalence of PADA was increased and that of PP formation was decreased in patients with BAMLIs. There was a significant relationship between skeletal anomalies and/or normal variants.

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.

Association between craniofacial morphological patterns and tooth agenesis-related genes

Background

The aim of the present study was to assess if genetic polymorphisms in tooth agenesis (TA)-related genes are associated with craniofacial morphological patterns.

Methods

This cross-sectional, multi-center, genetic study evaluated 594 orthodontic Brazilians patients. The presence or absence of TA was determined by analysis of panoramic radiography. The patients were classified according to their skeletal malocclusion and facial growth pattern by means of digital cephalometric analysis. Genomic DNA was extracted from squamous epithelial cells of buccal mucosa and genetic polymorphisms in MSX1 (rs1042484), PAX9 (rs8004560), TGF-α (rs2902345), FGF3 (rs1893047), FGF10 (rs900379), and FGF13 (rs12838463, rs5931572, and rs5974804) were genotyped by polymerase chain reaction using TaqMan chemistry and end-point analysis.

Results

Genotypes (p = 0.038) and allele (p = 0.037) distributions for the FGF3 rs1893047 were significantly different according to the skeletal malocclusion. Carrying at least one G allele increased in more than two times the chance of presenting skeletal class III malocclusion (OR = 2.21, CI 95% = 1.14–4.32; p = 0.017). There was no association between another skeletal craniofacial pattern and some polymorphism assessed in the present study.

Conclusion

Our results suggest that the genetic polymorphism rs1893047 in FGF3 might contribute to variations in the craniofacial sagittal pattern.

Association between Maternal Smoking during Pregnancy and Missing Teeth in Adolescents

Tooth agenesis and disturbance of tooth eruption is the most prevalent oral defect, and is possibly caused by the interaction of genetic and environmental factors. We hypothesized that prenatal factors may affect tooth development. The objective of this study was to examine whether smoking during pregnancy was associated with missing teeth in the offspring during adolescence. The study population comprised pregnant women and their children registered (N = 1052) at Koshu city, Japan. When the expectant mothers visited the city office for pregnancy registration, a survey was conducted to ascertain their lifestyle habits. Data on missing teeth in the children were obtained from the compulsory dental health checkup during junior high school years. Multivariate logistic regression models were fitted to assess the association between missing teeth and lifestyle habits. A total of 772 children were studied. The prevalence of missing teeth in these children was 4.9%. Children whose mothers smoked six cigarettes or more per day were 4.59 (95% CI: 1.07-19.67) times more likely to present with missing teeth than those children whose mothers did not smoke, after adjustment for possible confounders. Our findings indicate that smoking during pregnancy can be a risk factor for missing teeth in the offspring.

Craniofacial shape differs in patients with tooth agenesis: geometric morphometric analysis

Aim

To evaluate the shape of the craniofacial complex in patients with tooth agenesis and compare it to matched controls.

Subjects and methods

The sample comprised 456 patients that were allocated to three groups: the agenesis group of 100 patients with at least one missing tooth, excluding third molars, the third molar agenesis group (3dMAG; one to four missing third molars) of 52 patients and the control group (CG) of 304 patients with no missing teeth. The main craniofacial structures depicted on lateral cephalograms were digitized and traced with 15 curves and 127 landmarks. These landmarks were subjected to Procrustes superimposition and principal component analysis in order to describe shape variability of the cranial base, maxilla and mandible, as well as of the whole craniofacial complex. For statistical analysis, permutation tests were used (10 000 permutations without replacement).

Results

Approximately half of the sample's variability was described by the first three principal components. Comparisons within the whole sample revealed sexual dimorphism of the craniofacial complex and its structures (P < 0.01). Differences between the agenesis group and matched controls were found in the shape of all craniofacial structures except for the cranial base (P < 0.05). Specifically, patients with agenesis presented with Class III tendency and hypodivergent skeletal pattern. However, the comparison between the 3dMAG and matched CG revealed no differences.

Conclusion

The shape of the craniofacial complex differs in patients with tooth agenesis suggesting that common factors are implicated in tooth development and craniofacial morphology.

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.

Obeservations on association between third molar agenesis and craniofacial morphology

OBJECTIVE

This study was designed to examine the relationship between third molar agenesis and skeletal morphology in the Chinese population.

MATERIALS AND METHODS

A total of 1043 patients' records were analyzed with panoramic radiographs and cephalograms. Congenitally missing third molars were assessed with respect to gender, jaw, and side, and assessed in various types of facial morphology. Linear, angular, and proportional cephalometric measurements were analyzed and compared among the samples. For the evaluation of results, the following statistics were used: the Pearson χ ² test, one-way ANOVA, and the Student-Newman-Keuls method.

RESULTS

The overall prevalence of third molar agenesis was 28.7%. Missing third molars were more common in the maxilla and on the right side, while the difference was not statistically significant (P > 0.05) between genders. Every hypodontia group had a smaller SN-GoGn angle, Y-axis-FH angle, and a larger S-Go/N-Me ratio. The group with third molar agenesis in both jaws had smaller SNA and Wits values. The frequency of third molar agenesis in subjects with a Class II malocclusion was significantly lower than in other types of malocclusion (P < 0.05), and the incidence of third molar agenesis in hypodivergent growth pattern was higher than in other patterns (P < 0.05).

CONCLUSION

The results demonstrate a possible association between third molar agenesis and both sagittal and vertical craniofacial morphology.

Alveolar bone resorption after primary tooth loss has a negative impact on straightforward implant installation in patients with agenesis of the lower second premolar

OBJECTIVES

To compare the alveolar bone dimensions in patients with lower second premolar (P2) agenesis prior to and after primary molar loss on CT scans, and assess the possibility for straightforward implant placement.

METHODS

Alveolar bone dimensions were evaluated on 150 mandibular CT scans in three groups: (i) agenesis of P2, with the primary tooth in situ, and regularly erupted first premolar (P1) and molar (M1) (AW); (ii) agenesis of P2, without the primary tooth in situ for ≥3 m, but regularly erupted P1 and M1 (AWO); and (iii) P1, P2, and M1 regularly erupted (CTR). The possibility of straightforward placement of an implant 3.5 or 4.3 mm in Ø × 10 mm long was digitally simulated and compared to the actually performed treatment.

RESULTS

Buccolingual width (7.3 ± 2.0 mm) at the coronal aspect of the ridge in the AWO group was statistically significantly smaller comparing with both the AW (9.2 ± 1.4 mm) and the CTR (9.5 ± 1.1 mm) group; width reduction appeared to be mainly due to "collapse" of the buccal aspect of the ridge. Simulated straightforward placement of implants with a diameter of 3.5 or 4.3 mm was possible in 62% and 56% of the cases in the AWO vs. 86% and 84% in the AW group (p = .006 and .002, respectively). Straightforward implant placement was actually possible in all patients (22) in the AW group, while 28% (11 of 39) of the patients in the AWO group needed additional hard tissue augmentation.

CONCLUSIONS

Significant dimensional differences exist in the alveolar ridge, especially in the coronal part, at lower P2 agenesis sites missing the primary tooth for ≥3 m, when compared to P2 agenesis sites with the primary tooth in situ. It seems thus reasonable to advise that the primary second molar should be kept as long as possible, in order to facilitate straightforward implant installation and reduce the probability of additional bone augmentation procedures.

Effects of skeletally anchored Class II elastics: A pilot study and new approach for treating Class II malocclusion

OBJECTIVE

To evaluate the skeletal, dentoalveolar, and soft tissue effects of skeletally anchored Class II elastics and compare them with a matched control group treated by a monobloc appliance for the correction of skeletal Class II malocclusion due to mandibular retrusion.

MATERIALS AND METHODS

Twelve patients (6 girls, 6 boys) were randomly divided into two groups. In the elastics group, six patients (12.9 ± 1.5 years of age; 3 boys, 3 girls) were treated with skeletally anchored Class II elastics. Two miniplates were placed bilaterally at the ramus of the mandible and the other two miniplates were placed at the aperture piriformis area of the maxilla. In the monobloc group (3 boys and 3 girls; mean age, 12.3 ± 1.6 years), patients used the monobloc appliance. The changes observed in each phase of treatment were evaluated using the Wilcoxon matched-pair sign test. Intergroup comparisons at the initial phase of treatment were analyzed by the Mann-Whitney U test.

RESULTS

There were statistically significant group differences in Co-Gn, B-VRL, U1-PP, U1-VRL, Ls-VRL, with significant increases in these parameters in the elastics group (P < .05). The mandibular incisors were protruded in the monobloc group (5.45 ± 1.23°), whereas they were retruded in the elastics group (-3.01 ± 1.66°; P < .01).

CONCLUSIONS

The undesirable dentoalveolar effects of the monobloc appliance were eliminated by using miniplate anchorage. Favorable skeletal outcomes can be achieved by skeletal anchorage therapies which could be an alternative to treat skeletal Class II patients with mandibular deficiency.

Patterns of non-syndromic permanent tooth agenesis in a large orthodontic population

OBJECTIVE

The aim of this study is to explore patterns of non-syndromic permanent tooth agenesis in a large orthodontic patient group.

DESIGN

A record review was performed in various orthodontic clinics to identify white patients with non-syndromic permanent tooth agenesis, excluding 3rd molars. Four hundred and fourteen subjects fulfilled the inclusion criteria.

RESULTS

In the 414 subjects with tooth agenesis, approximately 70% presented 1-2 missing teeth. Symmetric agenesis patterns were often observed in the sample (by jaw, by side, or crossed quadrants), with prevalence approaching 30% for cases with contralateral tooth agenesis within a jaw. In cases with 1 or 2 missing teeth, from the total number of potential tooth agenesis patterns in the sample, a certain part was evident, limiting the variation to 27.8% (44/158). In the entire sample, both in the maxilla and the mandible a certain incisor/premolar agenesis phenotype was observed in 59.0% of cases in isolated form.

CONCLUSIONS

Although there was variation in the tooth agenesis patterns, our findings suggest the involvement of particular genetic, epigenetic, and/or environmental factors in the formation of the entire dentition, which often lead to specific tooth agenesis phenotypes in cases where this process is disrupted. The present study provides a comprehensive categorization of orthodontic cases with tooth agenesis and can assist in planning future epidemiological and genetic studies.

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 reliability of the Greulich and Pyle atlas when applied to a Southern Turkish population

OBJECTIVE

The aim of this study was to evaluate the applicability of Greulich and Pyle (GP) method for Southern Turkish population.

MATERIALS AND METHODS

Hand and wrist radiographs of 535 patients (276 females, 259 males aged from 10 to 18 years) selected retrospectively from the archive. Skeletal age (SA) estimation was performed according to GP atlas. The chronological age (CA) and SA were compared using the Paired t-test.

RESULTS

The mean difference between the CA and SA ranged from 0.07 to 1.11 years. These differences between the CA and estimated SA were statistically significant in group I (10-10.90 years) (P < 0.001), group II (11-11.90 years) (P < 0.050), group III (12-12.90 years) (P < 0.001), group IV (13-13.90 years) (P < 0.010), and group V (14-14.90 years) (P < 0.001) for females. The mean difference between the CA and SA ranged from -0.41 to -1.79 years for females. These differences between the CA and estimated SA were statistically significant in all age groups.

CONCLUSIONS

Statistically significant differences were found in the CA and SA assessed by GP method for the Southern Turkish sample. SA was significantly over-predicted in the 10-15 year ages in males and for 10-18 year ages for females. It is appropriate to use GP method in Southern Turkish children; however, a revision is needed for better results and to minimize the mistakes.

Assessment of hypodontia in the Turkish patients referring to the orthodontic clinic: A retrospective study

OBJECTIVE

The aim of this retrospective study was to assess the prevalence and distribution of hypodontia in the permanent dentition in a sample of Turkish patients who referred to the Ankara Dental Hospital for orthodontic treatment.

MATERIALS AND METHODS

The pre-treatment orthodontic records of 2530 patients, 1382 girls (54.62%) and 1148 boys (45.38%) between the chronological ages of 7 and 16 years, were examined for evidence of hypodontia. The third molars were excluded in this study.

RESULTS

The prevalence of hypodontia in the inspected population was 5% (3.05% for girls, 1.95% for boys). The average number of the congenitally missing teeth per patient was 2.03 (1.08 for girls, 0.95 for boys). The prevalence of the congenitally missing permanent teeth was 34% for the upper laterals, 30% for the lower second premolars, 12.5% for the upper second premolars and 23.5% for the other teeth. Most patients with hypodontia (84.9%) (57.13% for girls, 27.77% for boys) had got missing either one tooth (45.23%) or two teeth (39.67%).

CONCLUSIONS

The prevalence of hypodontia in girls was higher than in boys in this sample of the Turkish patients. The upper laterals and lower second premolars were consecutively the most symmetrically absent teeth. The prevalence of advanced hypodontia was lower than single and symmetrical hypodontia.