At the crossroads of oral facial genetics

Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners

AIM

The purpose of this study was to evaluate the mandibular growth and/or projection following maxillary incisor proclination, overbite correction, and maxillary dentoalveolar expansion without the use of any class II mechanics, in growing class II division 2 patients treated with clear aligners.

MATERIALS AND METHODS

Before and after treatment cone-beam computed tomographic (CBCT) generated lateral and posteroanterior cephalograms of thirty-two patients with skeletal class II division 2, 16 in the treatment group and 16 in the untreated group, were reviewed to evaluate treatment-related changes. Upper incisors were proclined and protruded, as well as upper arch expansion and overbite correction were performed as part of their regular treatment. Cephalometric analysis was performed to evaluate skeletal and dental changes. Unpaired statistical t-tests were performed to determine if significant skeletal class II correction was achieved in the treatment group.

RESULTS

In the treatment group, after treatment, the upper incisors became more proclined and protruded, and the inter-molar width increased while the overbite was reduced compared to the control group. An increase in skeletal mandibular growth and forward projection was also observed, thus contributing to an improvement of the sagittal skeletal relationship as evidenced by ANB and Wits values compared to the control group.

CONCLUSION

A combination of upper incisor proclination, correction of deep overbite, and maxillary dentoalveolar expansion using clear aligners appears to contribute to an improvement of the skeletal class II relationship in growing patients with class II division 2.

CLINICAL SIGNIFICANCE

This study shows that unlocking the mandible by correcting a deep overbite, proclining upper incisors, and expanding the upper arch in growing class II division 2 patients can improve skeletal class II using clear aligners. How to cite this article: Mirzasoleiman P, El-Bialy T, Wiltshire WA, et al. Evaluation of Mandibular Projection in Class II Division 2 Subjects Following Orthodontic Treatment Using Clear Aligners. J Contemp Dent Pract 2024;25(4):295-302.

Lingual frenulum length: A prospecting link to craniofacial morphology in adults

OBJECTIVES

The aim of this study was to evaluate the correlation of the length of the lingual frenulum with the craniofacial morphology in adults.

METHOD AND MATERIALS

The study comprised a total of 144 subjects, aged 18 to 28 years, divided into 3 groups (48 in each group), based on ANB angle i.e., Skeletal Class I, Skeletal Class II & Skeletal Class III. To measure the length of the lingual frenulum direct and indirect methods were used. A Lingual frenulum ruler was used for direct measurement and the differences between the maximum mouth opening reduction (MMOR) with and without the tip of the tongue touching the incisive papilla measurement were taken for the indirect method. A lateral cephalogram was collected from each subject and a cephalometric analysis was done to assess craniofacial morphology. Statistical analysis was done by ANOVA and the significance of the mean difference between (inter) the groups was done by Tukey's HSD (honestly significant difference) post hoc test after ascertaining normality by Shapiro-Wilk's test and homogeneity of variance between groups by Levene's test.

RESULTS

The lingual frenulum length and maximum mouth opening reduction were significantly increased in the Skeletal Class III subjects with a statistically significant value of P < 0.001 when compared with the Skeletal Class I and Skeletal Class II subjects.

CONCLUSION

A balance in the teeth positioning is maintained by orofacial musculature and any disturbance which occurs in this, results in malocclusion. Malocclusion can result in a long lingual frenulum that pushes the mandibular anterior forwards. Hence, the malocclusion and lingual frenulum length relationship are essential to eliminate the erratic forces and to attain excellent results, following the elimination of malocclusion.

Investigation of the Relationship between Sagittal Skeletal Nasal Profile Morphology and Malocclusions: A Lateral Cephalometric Film Study

The aim of this study was to evaluate the relationship between skeletal sagittal nasal profile morphology and sagittal skeletal malocclusions. Regarding lateral cephalometric films, the study was conducted in a total of 135 individuals without any prior orthodontic treatment (mean age of 17.91 ± 1.91), including 49 males (mean age 17.91 ± 1.16) and 86 females (mean age 17.78 ± 1.91 years). The groups were divided into two groups as male and female according to gender, and three groups as skeletal Class 1, Class 2, and Class 3 according to the Steiner's ANB angle. In addition, skeletal groups were compared within groups by dividing into two groups of male and female. A total of eight parameters, three skeletal sagittal angular (SNA, SNB, and ANB angles), four nasal linear (R-A, N-A, N-ANS, and N-R distances) and one nasal angular (N1-N2/N2-R angle), were measured on each cephalometric film. The arithmetic mean and standard deviation of all measured nasal parameters were calculated. For statistical analysis, independent sample t-test and one-way analysis of variance (One-Way ANOVA) were used for normally distributed data, and Mann Whitney U and Kruskal Wallis tests were used for data that did not show normal distribution. For statistical analysis, p < 0.05 was considered significant. R-A, N-A, and N-ANS linear nasal parameters differed significantly between the male and female groups, which were evaluated regardless of the skeletal groups, with a higher rate in males (p < 0.05). N-R linear nasal parameter showed a statistically significant difference between skeletal malocclusion groups, which were evaluated regardless of gender. N-R distance was found to be significantly longer in skeletal Class 3 individuals than in Class 1 and 2 individuals (p < 0.05). There was no statistically significant difference in nasal bone concavity angle in all groups (p > 0.05). R-A and N-A linear nasal parameters showed statistically significant differences between male and female sex groups in all skeletal malocclusion classes (p < 0.05). At first, results showed that males had longer measurements than females in all linear nasal parameters. Second, longer measurements were found in all linear nasal parameters in skeletal Class 3 individuals than those in skeletal Class 1 and Class 2 individuals. Third, the nasal bone concavity angle was greater in skeletal Class 2 individuals than the others.

Parathyroid Hormone Gene and Genes Involved in the Maintenance of Vitamin D Levels Association with Mandibular Retrognathism

In this study we evaluated whether single nucleotide polymorphisms (SNPs) in the genes encoding PTH, VDR, CYP24A1, and CYP27B1 were associated with mandibular retrognathism (MR). Samples from biologically-unrelated Brazilian patients receiving orthodontic treatment were included in this study. Pre-orthodontic lateral cephalograms were used to determine the phenotype. Patients with a retrognathic mandible were selected as cases and those with an orthognathic mandible were selected as controls. Genomic DNA was used for genotyping analysis of SNPs in PTH (rs694, rs6256, and rs307247), VDR (rs7975232), CYP24A1 (rs464653), and CYP27B1 (rs927650). Chi-squared or Fisher’s tests were used to compare genotype and allele distribution among groups. Haplotype analysis was performed for the SNPs in PTH. The established alpha was p < 0.05. Multifactor dimensionality reduction (MDR) was used to identify SNP–SNP interactions. A total of 48 (22 males and 26 females) MR and 43 (17 males and 26 females) controls were included. The linear mandibular and the angular measurements were statistically different between MR and controls (p < 0.05). In the genotype and allele distribution analysis, the SNPs rs694, rs307247, and rs464653 were associated with MR (p < 0.05). MDR analyses predicted the best interaction model for MR was rs694–rs927650, followed by rs307247–rs464653–rs927650. Some haplotypes in the PTH gene presented statistical significance. Our results suggest that SNPs in PTH, VDR, CYP24A1, and CYP27B1 genes are associated with the presence of mandibular retrognathism.

Genetics of Dentofacial and Orthodontic Abnormalities

The development of craniofacial complex and dental structures is a complex and delicate process guided by specific genetic mechanisms. Genetic and environmental factors can influence the execution of these mechanisms and result in abnormalities. An insight into the mechanisms and genes involved in the development of orofacial and dental structures has gradually gained by pedigree analysis of families and twin studies as well as experimental studies on vertebrate models. The development of novel treatment techniques depends on in-depth knowledge of the various molecular or cellular processes and genes involved in the development of the orofacial complex. This review article focuses on the role of genes in the development of nonsyndromic orofacial, dentofacial variations, malocclusions, excluding cleft lip palate, and the advancements in the field of molecular genetics and its application to obtain better treatment outcomes.

Professional consensus on orthodontic risks: What orthodontists should tell their patients

INTRODUCTION

Effective communication of risk is a requisite for valid consent, shared decision-making, and the provision of person-centered care. No agreed standard for the content of discussions with patients about the risks of orthodontic treatment exists. This study aimed to produce a professional consensus recommendation about the risks that should be discussed with patients as part of consent for orthodontic treatment.

METHODS

A serial cross-sectional survey design using a modified electronic Delphi technique was used. Two survey rounds were conducted nationally in the United Kingdom using a custom-made online system. The risks used as the prespecified items scored in the Delphi exercise were identified through a structured literature review. Orthodontists scored treatment risks on a 1-9 scale (1 = not important, 9 = critical to discuss with patients). The consensus that a risk should be discussed as part of consent was predefined as ≥70% orthodontists scoring risk as 7-9 and <15% scoring 1-3.

RESULTS

The electronic Delphi was completed by 237 orthodontists who reached a professional consensus that 10 risks should be discussed as part of consent for orthodontic treatment; demineralization, relapse, resorption, pain, gingivitis, ulceration, appliances breaking, failed tooth movements, treatment duration, and consequences of no treatment.

CONCLUSIONS

A professional orthodontic consensus has been reached that 10 key risks should be discussed with patients as part of consent for orthodontic treatment. The information in this evidence base should be tailored to patients' individual needs and delivered as part of a continuing risk communication process.

Heritability of teeth angulation and inclination in patients with overt malocclusion

PURPOSE

To use 3-dimensional cone beam computed tomography (CBCT) images obtained on patients before treatment with dental malocclusion to calculate the heritability estimates of full-tooth angulation and inclination. A heritability estimate is a number between zero and one indicating the percentage of genetic factors involved in determining the phenotypic variation observed.

METHOD

CBCT images of 111 patients (51 sibships) were analysed measuring both tooth angulation and inclination using the Anatomage Invivo5 software for central incisor to second molar. The long axis of each tooth was defined and traced as the cusp tip of the most mesiobuccal cusp to 6mm coronal to the apex of the mesiobuccal root. SPSS statistical software was used to analyse the data and calculate the heritability estimates for each tooth type in the maxilla and in the mandible regardless of the side.

RESULTS

Teeth inclination showed higher heritability estimates than tooth angulation. Furthermore, maxillary teeth showed higher heritability estimates than mandibular teeth and anterior teeth showed higher heritability than posterior teeth.

CONCLUSION

Genetic effect was more evident on tooth inclination than tooth angulation, on anterior teeth more than posterior teeth, and on maxillary teeth more than mandibular teeth.

Orthodontic treatment for deep bite and retroclined upper front teeth in children

BACKGROUND

A Class II division 2 malocclusion is characterised by upper front teeth that are retroclined (tilted toward the roof of the mouth) and an increased overbite (deep overbite), which can cause oral problems and may affect appearance.This problem can be corrected by the use of special dental braces (functional appliances) that move the upper front teeth forward and change the growth of the upper or lower jaws, or both. Most types of functional appliances are removable and this treatment approach does not usually require extraction of any permanent teeth. Additional treatment with fixed braces may be necessary to ensure the best result.An alternative approach is to provide space for the correction of the front teeth by moving the molar teeth backwards. This is done by applying a force to the teeth from the back of the head using a head brace (headgear) and transmitting this force to part of a fixed or removable dental brace that is attached to the back teeth. The treatment may be carried out with or without extraction of permanent teeth.If headgear use is not feasible, the back teeth may be held in place by bands connected to a fixed bar placed across the roof of the mouth or in contact with the front of the roof of the mouth. This treatment usually requires two permanent teeth to be taken out from the middle of the upper arch (one on each side).

OBJECTIVES

To establish whether orthodontic treatment that does not involve extraction of permanent teeth produces a result that is any different from no orthodontic treatment or orthodontic treatment involving extraction of permanent teeth, in children with a Class II division 2 malocclusion.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following electronic databases: Cochrane Oral Health's Trials Register (to 13 November 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2017, Issue 10), MEDLINE Ovid (1946 to 13 November 2017), and Embase Ovid (1980 to 13 November 2017). To identify any unpublished or ongoing trials, the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch) were searched. We also contacted international researchers who were likely to be involved in any Class II division 2 clinical trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of orthodontic treatments to correct deep bite and retroclined upper front teeth in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results to find eligible studies, and would have extracted data and assessed the risk of bias from any included trials. We had planned to use random-effects meta-analysis; to express effect estimates as mean differences for continuous outcomes and risk ratios for dichotomous outcomes, with 95% confidence intervals; and to investigate any clinical or methodological heterogeneity.

MAIN RESULTS

We did not identify any RCTs or CCTs that assessed the treatment of Class II division 2 malocclusion in children.

AUTHORS' CONCLUSIONS

There is no evidence from clinical trials to recommend or discourage any type of orthodontic treatment to correct Class II division 2 malocclusion in children. This situation seems unlikely to change as trials to evaluate the best management of Class II division 2 malocclusion are challenging to design and conduct due to low prevalence, difficulties with recruitment and ethical issues with randomisation.

Orthodontic treatment for deep bite and retroclined upper front teeth in children

BACKGROUND

A Class II division 2 malocclusion is characterised by upper front teeth that are retroclined (tilted toward the roof of the mouth) and an increased overbite (deep overbite), which can cause oral problems and may affect appearance.This problem can be corrected by the use of special dental braces (functional appliances) that move the upper front teeth forward and change the growth of the upper or lower jaws, or both. Most types of functional appliances braces are removeable and this treatment approach does not usually require extraction of any permanent teeth. Additional treatment with fixed braces may be necessary to ensure the best result.An alternative approach is to provide space for the correction of the front teeth by moving the molar teeth backwards. This is done by applying a force to the teeth from the back of the head using a head brace (headgear) and transmitting this force to part of a fixed or removable dental brace that is attached to the back teeth. The treatment may be carried out with or without extraction of permanent teeth.If headgear use is not feasible, the back teeth may be held in place by bands connected to a fixed bar placed across the roof of the mouth or in contact with the front of the roof of the mouth. This treatment usually requires two permanent teeth to be taken out (one on each side).

OBJECTIVES

To establish whether orthodontic treatment that does not involve extraction of permanent teeth produces a result that is any different from no orthodontic treatment or orthodontic treatment involving extraction of permanent teeth, in children with a Class II division 2 malocclusion.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following electronic databases: Cochrane Oral Health's Trials Register (to 10 January 2017), the Cochrane Central Register of Controlled Trials (CENTRAL) (the Cochrane Library, 2016, Issue 11), MEDLINE Ovid (1946 to 10 January 2017), and Embase Ovid (1980 to 10 January 2017). To identify any unpublished or ongoing trials, the US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform (apps.who.int/trialsearch) were searched. We also contacted international researchers who were likely to be involved in any Class II division 2 clinical trials.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of orthodontic treatments to correct deep bite and retroclined upper front teeth in children.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results to find eligible studies, and would have extracted data and assessed the risk of bias from any included trials. We had planned to use random-effects meta-analysis; to express effect estimates as mean differences for continuous outcomes and risk ratios for dichotomous outcomes, with 95% confidence intervals; and to investigate any clinical or methodological heterogeneity.

MAIN RESULTS

We did not identify any RCTs or CCTs that assessed the treatment of Class II division 2 malocclusion in children.

AUTHORS' CONCLUSIONS

It is not possible to provide any evidence-based guidance to recommend or discourage any type of orthodontic treatment to correct Class II division 2 malocclusion in children. Trials should be conducted to evaluate the best management of Class II division 2 malocclusion.

Changes in lips, cheeks and tongue pressures after upper incisor protrusion in Class II division 2 malocclusion: a prospective study

Background

The etiology of Class II division 2 (CII/2) malocclusion focuses on heredity; however lip, cheek, and tongue pressures that are associated with the environmental effect are considered to have an effect. The aim of this study was to evaluate the relation between perioral pressures and the upper incisor inclination in CII/2 malocclusion.

Methods

Twenty patients (8 females, 12 males; mean age 10.29 ± 0.90 years) with CII/2 malocclusion were included in the study group, and 15 patients (5 females, 10 males; mean age 10.56 ± 1.06 years) with Class I malocclusion were included. The upper incisors were protruded with a utility arch (0.016 × 0.022 in. blue elgiloy wire). Perioral pressure assessment was made with the Iowa Oral Pressure Instrument. Upper lip pressure, lower lip pressure, vertical lip pressure, left-right buccal pressures, swallowing, and maximum tongue pressures were measured. Repeated measure ANOVA was used to test the intragroup differences. Intergroup comparisons were made using two-way repeated measure ANOVA with Bonferroni correction. Relationships between the variables were analyzed using rank correlation (Spearman’s rho). The significance for all statistical tests was predetermined at p < 0.05.

Results

A significant change occurred in the upper lip pressure, lower lip pressure, and vertical lip pressure; however, significant difference was not found between the groups. Upper lip pressure increased significantly in both groups. In the CII/2 group, lower lip pressure increased after protrusion and decreased after retention, while vertical lip pressure decreased and then increased significantly. Left buccal pressure changes between the groups were not parallel. Right buccal pressure, swallowing, and maximum tongue pressure changes were not statistically significant. Statistically significant correlation was found between U1-NA (mm) and vertical lip pressure (r −0.467).

Conclusions

In the CII/2 group, upper lip pressure increased only in retention. Lower lip pressure increased and vertical lip pressure decreased after protrusion. Nevertheless, these changes did not remain stable after the retention period. The difference between groups was not statistically significant at the end of retention.

Review of the Genetic Basis of Jaw Malformations

Genetic etiologies for congenital anomalies of the facial skeleton, namely, the maxilla and mandible, are important to understand and recognize. Malocclusions occur when there exist any significant deviation from what is considered a normal relationship between the upper jaw (maxilla) and the lower jaw (mandible). They may be the result of anomalies of the teeth alone, the bones alone, or both. A number of genes play a role in the facial skeletal development and are regulated by a host of additional regulatory molecules. As such, numerous craniofacial syndromes specifically affect the development of the jaws. The following review discusses several genetic anomalies that specifically affect the bones of the craniofacial skeleton and lead to malocclusion.

Two-dimensional morphometric analysis of young Asian females to determine attractiveness

Introduction:

Attractive people do not seem to consistently possess such ideal characteristics or share common features. There is no general consensus about the linear and angular characteristics that discriminate between attractive and normal persons.

Aim:

This study determines how young Asian women considered to be attractive differ in their twodimensional facial characteristics from normal women of the same age and race.

Materials and Methods:

Frontal and lateral photographs of 70 young Asian females were taken under standardized setting and were given to 15 judges who did not know the subjects in the study, to rate the attractiveness of each photograph. All 70 photographs were arranged in descending order of their total score by all the judges and were classified into three groups. Three angular, 8 linear measurements, and 3 ratios were compared between these groups.

Results:

This study showed that most attractive group had least convex face, larger forehead, and wider faces. Conversely, the middle facial height was larger in the least attractive group. The ratio of middle third to total face of the most attractive group is higher than the average attractive ones. The ratio of lower third to total face of the most attractive group is lower than the average attractive ones.

Assessment of lingual frenulum lengths in skeletal malocclusion

BACKGROUND

The orofacial musculature plays a pivotal role in maintaining a balance in positioning of the teeth and any imbalance which occurs in this , results in malocclusion. Lingual frenum is a soft tissue structure which tethers the ventral surface of the tongue to the floor of the mouth.

OBJECTIVE

This study was performed to analyze the lingual frenal lengths in skeletal class I, class II and Class III malocclusion and to correlate relationship between both.

MATERIALS AND METHODS

This study comprised of 30 subjects, with 10 in each group and an impression was made with the maximum mouth opening position and the tip of tongue touching the incisive papilla. The length of the lingual frenum was then measured from the casts. The maximum mouth opening position was also determined by measuring the interincisal distance with the maximum mouth opening position. Statistical analysis was done to analyze the relationship between both.

RESULTS

The lingual frenum was found to be longest in class III malocclusion, with a statistical significant value of p<0.01. The class II and class I malocclusion did not show much difference. The maximum mouth opening position was also increased in class III malocclusion, followed by class II and class I malocclusion, in a descending order.

CONCLUSION

The lingual frenum exerts erratic forces and a long lingual frenum pushes the mandibular anteriors forwards, resulting in malocclusion. Hence, a relationship between the lingual frenum and malocclusion is essential, so that the erratic forces can be eliminated and excellent results can be achieved, following the correction of malocclusion.

The comparison of facial estethics between orthodontically treated patients and their parents

Orthodontists emphasize the importance of facial esthetics while planning a treatment, and orthodontist state that orthodontics have more than expected effects on dentofacial esthetics. The facial esthetics of treated patients and their parents was analyzed and compared to define facial growth and to use in forensic sciences. Our study was applied to 45 orthodontic patients who were treated in our clinic and their untreated parents. The patients were divided into Classes I, II, and III groups according to their malocclusions. Pre- and posttreatment changes, pretreatment facial esthetics of the paitents and its accordance with their parents, and the calculation of heritability tests were performed. After the statistics, for pre- and posttreatment changes, all the groups except Class I revealed significant changes. There were significant correlations of patients for the heritability values and pretreatment esthetic in accordance with parents, but there were more correlations of fathers when compared to mothers. The facial esthetics in adolescences is related with so many factors, not only related with one factor. The facial esthetics in fact includes the aim of evaluation of facial properties partly or totally. Because orthodontic treatments affect facial esthetics, performing similar studies for the treatment outcomes, capabilities, and borders is important.

Different manifestations of Class II Division 2 incisor retroclination: a morphologic study

INTRODUCTION

The aims of this study were to investigate whether there is a different transverse morphologic pattern of dental arches among patients with different manifestations of Class II Division 2 incisor retroclination and to evaluate to what extent the pattern of smaller-than-average teeth in Class II Division 2 malocclusion is common to all groups studied. This information might clarify whether different Class II Division 2 phenotypes represent a single etiology or multiple etiologies.

METHODS

The sample comprised 108 subjects with Class II Division 2 malocclusions, divided into 2 groups according to the type of incisor retroclination: group I included 43 Class II Division 2 subjects with retroclination exclusively of the maxillary central incisors, and group II included 65 Class II Division 2 subjects with retroclination of the 4 maxillary incisors. Maxillary and mandibular intercanine and intermolar widths as well as mesiodistal crown dimensions of the 4 maxillary and mandibular incisors were determined from the patients' initial study models. Mean values of all variables were compared between the 2 groups by sex with analysis of variance.

RESULTS

From the comparison between these 2 groups, no statistically significant differences were found for all transverse measurements (P >0.05). For all mesiodistal measurements analyzed, statistically significant differences between the groups were only found for the mean value of both maxillary lateral incisors' mesiodistal dimensions in both sexes (P <0.05).

CONCLUSIONS

It is not possible to attribute a characteristic pattern of dental arch-width and incisor mesiodistal dimensions to the different manifestations of incisor retroclination in Class II Division 2 malocclusion.

A case of cleidocranial dysostosis: dilemma for a prosthodontist

Cleidocranial dysostosis (CCD) is an uncommon, generalized skeletal disorder characterized by delayed ossification of the skull, aplastic or hypoplastic clavicles, and complex dental abnormalities such as retention of multiple deciduous teeth, impaction or delayed eruption of permanent teeth and presence of supernumerary teeth. This case report describes a 30-year old male patient of CCD with classical findings and the challenges faced in his prosthodontic rehabilitation. Conventional complete dentures following interim complete dentures therapy had to be given as all other treatment modalities were ruled out because of anatomic limitations. Despite the disadvantages of removable dentures the patient adapted admirably to them with significant improvement in self-esteem. Though orthodontic and surgical correction may be the treatment of choice, the need to preserve the alveolar ridge could make fabrication of removable dentures in such patients, a viable option.

Cleidocranial dysplasia presenting with retained deciduous teeth in a 15-year-old girl: a case report

Introduction

Cleidocranial dysplasia is a rare congenital defect of autosomal dominant inheritance caused by mutations in the Cbfa1 gene, also called Runx2, located on the short arm of chromosome 6. It primarily affects bones which undergo intramembranous ossification. This condition is of clinical significance to dentistry due to the involvement of the facial bones, altered eruption patterns and multiple supernumerary teeth.

Case presentation

Our patient, a 15-year-old Indian girl, presented with the typical features of prolonged retention of deciduous dentition and delayed eruption of permanent teeth, that is, mandibular prognathism along with other skeletal abnormalities like shrugged shoulder and the absence of clavicles. A multidisciplinary approach was followed, comprising orthodontic, surgical and pedodontic teams for management.

Conclusion

Successful treatment of such a case lies in a holistic approach that takes care of all aspects, including the primary pathology, the deformity itself and even the psychological angle.

Orthodontic treatment for deep bite and retroclined upper front teeth in children

BACKGROUND

Correction of the type of dental problem where the bite is deep and the upper front teeth are retroclined (Class II division 2 malocclusion) may be carried out using different types of orthodontic treatment. However, in severe cases, surgery to the jaws in combination with orthodontics may be required. In growing children, treatment may sometimes be carried out using special upper and lower dental braces (functional appliances) that can be removed from the mouth. In many cases this treatment does not involve taking out any permanent teeth. Often, however, further treatment is needed with fixed braces to get the best result. In other cases, treatment aims to move the upper first permanent molars backwards to provide space for the correction of the front teeth. This may be carried out by applying a force to the teeth and jaws from the back of the head using a head brace (headgear) and transmitting this force to a part of a fixed or removable dental brace. This treatment may or may not involve the removal of permanent teeth. In some cases, neither functional appliances nor headgear are required and treatment may be carried out without extraction of any permanent teeth. Instead of using a headgear, in certain cases, the back teeth are held back in other ways such as with an arch across or in contact with the front of the roof of the mouth which links two bands glued to the back teeth. Often in these cases, two permanent teeth are taken out from the middle of the upper arch (one on each side) to provide room to correct the upper front teeth. It is important for orthodontists to find out whether orthodontic treatment only, carried out without the removal of permanent teeth, in children with a Class II division 2 malocclusion produces a result which is any different from no orthodontic treatment or orthodontic treatment only involving extraction of permanent teeth.

OBJECTIVES

To establish whether orthodontic treatment, carried out without the removal of permanent teeth, in children with a Class II division 2 malocclusion, produces a result which is any different from no orthodontic treatment or orthodontic treatment involving removal of permanent teeth.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE were searched. The handsearching of the main international orthodontic journals was updated to April 2006. There were no restrictions with regard to publication status or language of publication. International researchers, likely to be involved in Class II division 2 clinical trials, were contacted to identify any unpublished or ongoing trials.

SELECTION CRITERIA

Trials were selected if they met the following criteria: randomised controlled trials (RCTs) and controlled clinical trials (CCTs) of orthodontic treatments to correct deep bite and retroclined upper front teeth in children.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were to be conducted in duplicate and independently by two review authors. Results were to be expressed as random-effects models using mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals. Heterogeneity was to be investigated including both clinical and methodological factors.

MAIN RESULTS

No RCTs or CCTs were identified that assessed the treatment of Class II division 2 malocclusion in children.

AUTHORS' CONCLUSIONS

It is not possible to provide any evidence-based guidance to recommend or discourage any type of orthodontic treatment to correct Class II division 2 malocclusion in children.

Severe hypodontia in a set of triplets

Hypodontia is the developmental absence of one or more teeth from the dentition and constitutes one of the most common developmental anomalies in humans with a reported prevalence of 1.6 to 9.6% in the permanent dentition. Hypodontia may occur in association with other genetic diseases, or as an isolated familial or sporadic form. This article describes the rare phenomenon of severe hypodontia in a set of triplets. The triplets presented with congenital absence of the second molars, second premolars in all quadrants and lower central incisors. An additional five teeth (upper canines, upper lateral incisors and upper left first premolar) were missing in one of the triplets. The treatment plan and the possible genetic mode of inheritance are discussed.

The use of parental data to evaluate soft tissues in an Anatolian Turkish population according to Holdaway soft tissue norms

INTRODUCTION

The relative influence of genetic and environmental factors in the etiology of malocclusion has long been a matter for discussion. The aim of this study was to compare the soft tissue structures of parents and their prepubertal, pubertal, and postpubertal offspring according to the Holdaway soft tissue norms to determine the similarity among them. Differences related to age and sex between the parents and offspring were also evaluated.

METHODS

Lateral cephalometric radiographs were used to determine the similarities in soft tissue structures in 120 families, which were divided into prepubertal (n = 40), pubertal (n = 40), and postpubertal (n = 40) groups according to the children's skeletal ages. A total of 12 variables (2 angular and 10 linear) were measured according to Holdaway's soft tissue analysis. Pairs were formed between family members (mother to son, mother to daughter, father to son, father to daughter, midparent (mean of the father's and mother's values) to son, and midparent to daughter) in each group. Descriptive statistics and multiple linear regression analysis were performed.

RESULTS

Statistically significant correlations between parents and their offspring were found. The parental data showed that a mother's genetic influence on her child's soft tissues was greater than the father's. Moreover, it was found that daughters had greater genetic influences from their parents than did sons. As age increased, the similarity was greater. Soft tissue facial angle (beta: 0.671), soft tissue chin thickness (beta: 0.549), and basic upper lip thickness (beta: 0.537) were the most similar variables between parents and their offspring.

CONCLUSIONS

A few selected cephalometric measurements of the parents might furnish important data to the clinician in predicting a child's facial growth characteristics and aging process.

The postural basis of malocclusion: a philosophical overview

Over the last 100 years, many theories have attempted to explain the cause of malocclusion. Most have stated that it is inherited, but, more recently, greater emphasis has been placed on the influence of the environment, especially the activity and the posture of the oral soft tissues. Unfortunately, it is not possible to measure long-term posture with any precision, and this has reduced its perceived importance. When some evidence is missing and much of the rest conflicting, there is merit in moving from the traditional "prove-it" attitude to philosophical reasoning to separate the probable from the improbable. We do not know to what extent posture and parafunction might be inherited, but there can be no doubt that facial and dental structures are, at times, strongly influenced by the soft tissues and that some malocclusions appear to have a postural basis. This article undertakes a philosophical examination of the conflicting strands of evidence that link oral posture with malocclusion, hoping to create a theory based solely on the restricted evidence that is broadly accepted by all sides in this age-old debate.

Three-dimensional assessment of the relative contribution of genetics and environment to various facial parameters with the twin method

The purpose of this prospective study was to help distinguish the relative contributions of heredity and environment to the external facial features and to assess the relative strength of the genetic influence on anteroposterior and vertical facial parameters, by using 3-dimensional optical surface scanning and the inferential twin method. The subject group consisted of 10 pairs of monozygotic twins (5 male, 5 female, mean age 11.9 years), 10 pairs of same-sex dizygotic twins (3 male, 7 female, mean age 12.1 years), and 6 mixed-sex dizygotic twin pairs. Two methods of analysis were used on the 3-dimensional scans. Interlandmark measurements of 28 facial parameters were recorded, and the mean intrapair differences for each parameter were compared between the monozygotic and dizygotic groups. The second method used the analysis of surface shape for all twin pairs. This technique characterizes the face by using 9 surface shapes distinguished visually by color, allowing a qualitative description of the differences between monozygotic and dizygotic twin pairs. Analysis of the 28 facial parameters showed significant ( P< .05) genetic determination for midfacial parameters, especially left eye width, intercanthal width, nose height, and nose width. Analysis of surface shape showed the strongest genetic determination for a triangular area of the midface encompassing the orbital rims, intercanthal area, and nose. The concordance for vertical and anteroposterior facial parameters was found to be greater in monozygotic twins than in dizygotic twins. The concordance for vertical facial dimensions of the middle and lower anterior parts of the face was found to be greater than that for anteroposterior facial dimensions in monozygotic twins.

Genetic aspects of dental disorders

This paper reviews past and present applications of quantitative and molecular genetics to dental disorders. Examples are given relating to craniofacial development (including malocclusion), oral supporting tissues (including periodontal diseases) and dental hard tissues (including defects of enamel and dentine as well as dental caries). Future developments and applications to clinical dentistry are discussed. Early investigations confirmed genetic bases to dental caries, periodontal diseases and malocclusion, but research findings have had little impact on clinical practice. The complex multifactorial aetiologies of these conditions, together with methodological problems, have limited progress until recently. Present studies are clarifying previously unrecognized genetic and phenotypic heterogeneities and attempting to unravel the complex interactions between genes and environment by applying new statistical modelling approaches to twin and family data. Linkage studies using highly polymorphic DNA markers are providing a means of locating candidate genes, including quantitative trait loci (QTL). In future, as knowledge increases; it should be possible to implement preventive strategies for those genetically-predisposed individuals who are identified to be at risk.

Hypodontia: genotype or environment? A case report of monozygotic twins

A case report is presented of monozygotic twins with variable expression of hypodontia. DNA fingerprinting was used to confirm monozygosity, and this evidence supports the theory that genetic coding is not the sole controlling factor in tooth agenesis. It is suggested that DNA fingerprinting should be considered the gold standard for determination of monozygosity.