Familial human hypodontia--is it all in the genes?

The Prevalence of Congenitally Missing Permanent Teeth in a Sample of Orthodontic and Non-Orthodontic Caucasian Patients

BACKGROUND

Hypodontia represents a notable clinical and public health concern.

OBJECTIVE

To assess the prevalence of congenitally missing permanent teeth in a sample of orthodontic/dental patients of Caucasian origin originating from the Greek island of Lesvos.

MATERIALS AND METHODS

Panoramic X-rays from 621 children and adolescents, aged 9 to 16 years (average age 12.5 years), 521 seeking orthodontic care (orthodontic group) and 100 seeking dental care (non-orthodontic group) were examined to identify congenitally missing permanent teeth.

RESULTS

The orthodontic group exhibited a 5.5% prevalence of congenitally missing permanent teeth (2.8% females; 2.7% males), while the non-orthodontic group showed a prevalence of 4% (3% females; 1% males). The descending order of prevalence for missing tooth types was as follows: lower second premolars, upper laterals, lower central incisors, lower canines, upper second premolars, and lower second molars. Among orthodontic patients with missing teeth, 62% presented with an Angle's Class II malocclusion. Hypodontia was most frequently observed in the mandible. No statistically significant differences were observed between the orthodontic and non-orthodontic groups in terms of the percentage of children and types of congenitally missing teeth.

CONCLUSIONS

Congenitally missing teeth were observed in about 4-5% of the studied population with a female predilection. The lower second premolar was the most commonly absent tooth, followed by the maxillary lateral incisors. An Angle's Class II malocclusion was present in the majority of orthodontic patients with hypodontia, mostly in the mandible.

The impact of orthodontic treatment on a young person's quality of life, esthetics, and self-esteem in hypodontia: A longitudinal study

INTRODUCTION

This research aimed to evaluate the impact of orthodontic treatment on a young person's oral health-related quality of life, self-esteem, and esthetics concerning hypodontia.

METHODS

A prospective longitudinal hospital-based study recruited 97 participants with hypodontia, aged 11-18 years. Forty-one participants (42%) originally planned to have space closure and the remainder space opening, with subsequent prosthetic replacement. The following questionnaires were completed before and after orthodontic treatment: the child perception questionnaire, Bristol condition-specific questionnaire for hypodontia (BCSQ), the child health questionnaire, and the Oral Aesthetic Subjective Impact Scale (OASIS). The Wilcoxon and matched pairs t tests approach was applied to compare before and after orthodontic treatment for significant testing (P <0.05).

RESULTS

Fifteen participants were lost to follow-up, resulting in 82 participants completing orthodontic treatment, with an average age of 13.8 ± 1.71 years. A total of 282 teeth were missing in the sample. Treatment resulted in significantly lower indexes (P <0.001) to overall BCSQ, OASIS, appearance, and how others would treat them. In comparing the 2 subgroups, those treated with space closure had significantly reduced functional limitations (child perception questionnaire), appearance concerns, self-esteem (child health questionnaire), OASIS, and overall BCSQ scores.

CONCLUSIONS

Orthodontic treatment in participants with hypodontia appears to significantly impact a range of psychological and esthetic scales. In particular, space closure appears to significantly improve the quality of life of participants compared with those undergoing space opening.

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.

The genetic basis of hypodontia in dental development

Dental agenesis is one of the most common developmental anomalies in humans, characterised by the developmental absence of one or more teeth. It can present as an isolated condition (non-syndromic hypodontia) or associated with a syndrome (syndromic hypodontia). This paper aims to review the genetic basis of hypodontia with reference to aetiology, classification and the subsequent clinical features.Significant progress has been made to identify the developmental basis of tooth formation, though there is still a lack of knowledge within the literature of the aetiological basis of inherited tooth loss.Gene anomalies or mutations in WNT10A, MSX1, PAX9, AXIN2 and EDA appear to be most critical during tooth development, leading to various forms of tooth agenesis.

Criteria for early diagnosis of third molar agenesis: a retrospective radiographic study

OBJECTIVE

To explore the association between chronological, dental and skeletal ages and early diagnosis of third molars agenesis.

MATERIAL AND METHODS

This retrospective radiographic study comprised a sample of 282 Portuguese patients (122 males and 160 females) who sought orthodontic treatment between 2007 and 2018. Each participant had panoramic and lateral cephalometric radiographs performed before and after the age of 14 years. The chronological age was categorized into three intervals between 11.0 and 13.11 years of age. The full eruption of the four-second molars was used as a criterion in determining dental age. Skeletal age was verified by the vertebral maturation method. The diagnosis of agenesis of third molars was initially performed by observation of the initial panoramic radiography undertaken before the age of 14 years. Subsequently, the diagnosis of agenesis of third molars was confirmed by visualizing the second panoramic radiography, obtained after the age of 14 years. The association between the accuracy of the diagnosis and the chronological, dental and skeletal ages was evaluated using the chi-square test, at a 5% significance level.

RESULTS

No significant association between chronological age and alterations in the diagnosis of third molar agenesis was identified. However, there was a significant association between third molar agenesis and both dental age (p<0.001) and skeletal age (p=0.006).

CONCLUSION

The eruption of the four-second molars and the peak of growth could be considered as criteria for early diagnosis of third molar agenesis, whereas chronological age is not a reliable diagnostic indicator.

The paediatric dentistry-restorative dentistry interface

This paper examines the various contemporary clinical interfaces between paediatric dentistry and restorative dentistry for patients with both acquired and congenital abnormalities presenting to primary and secondary care. Dental trauma of the child or adolescent has long-standing implications on future oral health due to conditions such as ankylosis, pulp necrosis, coronal tissue loss or tooth loss, all of which provide significant challenges into adulthood. Similarly, congenital conditions, such as hypodontia and structural deficiencies or malformations, such as amelogenesis and dentinogenesis imperfecta, result in the need for collaborative, multi-speciality decision-making from a young age, creating a pathway for longitudinal multi-disciplinary team treatment planning.

Effects of inflammation in dental pulp cell differentiation and reparative response

The responsiveness of the dentin-pulp complex is possible due to the stimulation of dental pulp cells, which begin to synthesize and secrete dentin matrix. The inflammatory process generated by harmful stimuli should be understood as a natural event of the immune response, resulting in the recruitment of hematopoietic cells, which cross the endothelial barrier and reach the site affected by the injury in order to eliminate the damage and provide an appropriate environment for the restoration of homeostasis. The repair process occurs in the presence of adequate blood supply, absence of infection, and with the participation of pro-inflammatory cytokines, growth factors, extracellular matrix components, and other biologically active molecules. Prostaglandins and leukotrienes are bioactive molecules derived from the metabolism of arachidonic acid, as a result of a variable range of cellular stimuli. The aim of this review is to describe the process of formation and biomineralization of the dentin-pulp complex and how pro-inflammatory events can modify this response, with emphasis on the lipid mediators prostaglandins and leukotrienes derived from arachidonic acid metabolism.

Tooth agenesis in German orthodontic patients with non-syndromic craniofacial disorder: a retrospective evaluation of panoramic radiographs

Objectives

The study objective was to evaluate the tooth agenesis in German orthodontic patients with non-syndromic cleft lip and/or palate and Robin sequence compared to a control group without craniofacial disorder.

Materials/methods

A total of 108 panoramic radiographs were examined using the binary system of Tooth Agenesis Code (TAC) (excluding the third molar). Patients were divided into the craniofacial disorder group 1 (n = 43) and the healthy control group 2 (n = 65). Parameters such as skeletal class malformation, sex, localization of the cleft, craniofacial disorder, and interobserver reliability were assessed.

Results

Permanent tooth agenesis was observed in 44% of group 1 and 14% in group 2 with a statistically significant higher prevalence (p = 0.00162 (χ²)). Fourteen different TAC patterns were observed in group 1, ten of these occurring only once in separate patients. The distribution of the TAC codes in group 2 showed nine different possibilities of TAC code patterns; seven TACs were unique. In group 1, the most frequently absent teeth were the maxillary lateral incisor of the left side (30%); in group 2, the second premolar of the lower jaw on the right side (9%). Male patients with craniofacial disorder showed a higher percentage of tooth agenesis than female.

Conclusion

The data presented here shows a statistically significant higher prevalence of tooth agenesis in German patients with non-syndromic craniofacial disorder.

Clinical relevance

Radiographic evaluation enables the diagnosis of tooth agenesis. Recognizing early on the higher prevalence of tooth agenesis in patients exhibiting a craniofacial disorder is an important issue when developing long-term and comprehensive interdisciplinary treatment.

Dental anomalies in non-syndromic orofacial clefts: a clinical approach

Orofacial clefts (OC) represent some of the most common congenital malformations and affect multiple structures in the craniofacial region. There are a wide range of morphological OC types within the spectrum of both non-syndromic OC (NSOC) and syndromic OC, including cleft lip (CL); cleft lip and palate (CLP) and cleft palate (CP). Here, we describe the most frequent dental anomalies seen in the permanent dentition of individuals with NSOC, comparing them between the three main cleft types (CL, CLP, CP). We present these findings from the perspective of prevalence relating to each anomaly, as well as the clinical characteristics and potential impact in the rehabilitation process. The investigation of dental anomalies associated with NSOC is important, helping to expand the phenotypic characterization of NSOC, improve initial diagnostics and establish appropriate rehabilitation and counseling.

The Human Genetics of Dental Anomalies

The development of tooth is a highly complex procedure and mastered by specific genetic programs. Genetic alterations, environmental factors, and developmental timing can disturb the execution of these programs, and result in various dental anomalies like hypodontia/oligodontia, and supernumerary teeth, which are commonly seen in our clinical practice. Advances in molecular research enabled the identification of various genes involved in the pathogenesis of dental anomalies. In the near future, it will help provide a more accurate diagnosis and biological-based treatment for these anomalies. In this article, we present the molecular phenomenon of tooth development and the genetics of various dental anomalies.

The prevalence and management of patients with hypodontia: A cross -sectional study

BACKGROUND

Hypodontia is one of the most common anomalies in dentistry. Hypodontia has a negative impact on oral health-related quality of life with patients best seen in a multidisciplinary clinic to improve treatment outcomes.

AIM

To investigate the prevalence of hypodontia and its association with other dental anomalies, as well as malocclusion, and to investigate the treatment planned for patients attending the clinic and whether the type of missing teeth affected the proposed treatment.

MATERIALS AND METHODS

Analysis of consecutive patients attending the hypodontia clinic at a dental hospital between February and November 2020. A total of 100 patients who met the inclusion criteria were identified. Data collected included the following: age/sex; number and type of missing teeth; pre-treatment occlusion; presence of other dental anomalies; and planned treatment.

RESULTS

A total of 100 patients (55% female; age range = 7-41 years; mean age = 18 years) were included. Of the cohort, 47% had a class I skeletal relationship and participants were significantly less likely to have a class III skeletal or incisor relationship; 45% had another dental anomaly with the most common being microdontia. Space opening was the preferred treatment option for those managed by orthodontic treatment with resin-bonded bridges most likely to be used for restoration of spaces, 86%.

CONCLUSION

Lower second premolars were the most commonly missing teeth. Participants were significantly less likely to have a class III incisor or skeletal relationship than class I or II. Space opening was the favoured approach for orthodontic treatment, particularly for maxillary lateral incisors.

Research algorithm for the detection of genetic patterns and phenotypic variety of non-syndromic dental agenesis

Introduction: Dental agenesis (DA), brings together the anodontia, oligodontia, hypodontia, characterized by a deficit in the development of a variable number of teeth. The objectives of the study were to illustrate the phenotypic variability of non-syndromic DA, to identify cases of DA with hereditary genetic transmission, and establish the mode of DA genetic pattern in these cases, together with the determination of DA prevalence in the population group study. Patients, Materials and Methods: The cross-sectional observational study was performed on a mixed population group, consisting of 861 Caucasian patients, between January 2018–December 2019. The clinical evaluation protocol of patients with DA, used to illustrate their phenotype, included the following stages: oral examination, photographic examination, and radiological examination. The evaluation protocol specific to the family genetic study of patients with DA, involved the following three stages: family survey, construction of the family tree and analysis of the pedigree structure. Results: The prevalence of DA in the population group was 2.78%. Regarding the phenotype, DA mainly affected the upper arch (50% of cases); bilateral DA had a significantly increased incidence (83.33% of cases) compared to unilateral form; in most cases (75%), a patient lacked one to two teeth, the lack of two teeth being the most common form (83.33% of cases); the upper lateral incisors were the teeth most frequently involved in DA (31.11% of the total missing teeth). Regarding the family genetic study, hereditary DA with autosomal dominant inheritance was present in 37.50% of cases. In the other cases (62.50%), isolated, sporadic forms of DA were registered, suggesting a spontaneous de novo mutation or a disorder of odontogenesis of a non-genetic nature. Conclusions: We consider that this study is of interest for current scientific research with applicability in dental medicine, by bringing actual information on the prevalence of non-syndromic DA in South-East Romania, the variety of phenotypic spectrum of DA for this geographic area, and the role of heredity in the DA genetic determinism in the studied population.

Hypodontia and its impact on a young person's quality of life, esthetics, and self-esteem

INTRODUCTION

The impact of hypodontia on quality of life is a relatively unexplored area. The limited research shows that the issues of importance for people with hypodontia can vary from those of patients undergoing routine orthodontic treatment. This research aimed to use generic and condition-specific scales to evaluate the impact of hypodontia on a young person's oral health-related quality of life, self-esteem, and aesthetics.

METHODS

This prospective cross-sectional hospital-based study recruited 97 participants with hypodontia, aged 11-18 years. The following questionnaires were completed before the start of any planned treatment: child perception questionnaire, Bristol condition-specific questionnaire for hypodontia, child health questionnaire, and Oral Aesthetic Subjective Impact Scale. A priori sample size calculation determined a minimum of 65 participants were required, at the 5% level of significance, and with a power of 80%. The number was inflated to allow for dropouts/loss to follow-up by 30%.

RESULTS

A total of 323 teeth were missing; 58 subjects (36 female) showed mild (2 absent teeth), and 39 subjects (25 female) showed moderate to severe (>2 absent teeth) hypodontia. Forty-one (42%) patients were missing anterior teeth, with absent maxillary lateral incisors predominating. Significant differences were found for the overall child perception questionnaire (P = 0.01), emotional (P = 0.005), and social (P = 0.003) well-being; scores were highest in the moderate to severe hypodontia group, revealing the greatest negative impact. Similarly, overall Bristol condition-specific questionnaire for hypodontia (P <0.001), treatment (P = 0.001), appearance (P = 0.013), and other people's reaction (P <0.001) domains were all significant, with the moderate to severe group reporting higher levels of negative impact. No significant differences were observed in self-esteem or esthetics.

CONCLUSIONS

Hypodontia in young people appear to have a negative psychosocial impact, both in terms of its presentation and planned care.

Interdisciplinary treatment with implant-supported two-unit cantilever prosthesis for a patient with hypodontia: A clinical report

A 21-year-old woman with multiple congenitally missing maxillary anterior teeth received interdisciplinary treatment to restore function and esthetics. The treatment was initiated with orthodontic treatment, followed by implant placement, bone and soft-tissue augmentation, and prosthetic treatment including a screw-retained implant-supported 2-unit cantilever fixed dental prosthesis.

Association between tooth agenesis and cancer: a systematic review

The congenital absence of multiple teeth may share the same genetic background of the development of some types of cancer. Objective: This systematic review aimed to investigate the possible association between dental agenesis and cancer, and the perspective of agenesis as an early predictor for cancer risk. Methodology: The electronic databases PubMed, Scopus, Web of Science, Cochrane Library, LILACS, and OpenGrey were searched and the risk of bias was evaluated using the Newcastle-Ottawa tool. The GRADE tool was used to evaluate the certainty of the evidence. Results: Six studies met the eligibility criteria. A positive co-occurrence between ovarian cancer and hypodontia was found in two articles. Three studies evaluated the association between dental agenesis and colorectal cancer and only one showed common genes for these conditions. One paper found individuals with hypodontia had a higher risk of family history of cancer. Five studies had a fair quality and one a good quality. The certainty of evidence was classified as very low. Conclusion: Notwithstanding the limited scientific evidence, there may be a possible association between dental agenesis and cancer due to genes involved in both conditions. Agenesis of multiple teeth could be an early indicator of cancer risk. Nevertheless, studies with a better level of evidence are needed to confirm this possible association.

Evidence of dental agenesis in late pleistocene Homo

OBJECTIVE

Differential diagnosis and tabulation of cases of dental agenesis in Middle and Upper Paleolithic Western Eurasian humans to synthesize this data and to test previous hypotheses about when recent human patterns of third molar agenesis were established.

MATERIALS

139 Late Pleistocene human remains and 149 individuals from three Epi-Paleolithic/ Holocene non-agricultural comparative collections.

METHODS

All remains were visually and radiographically recorded by the author.

RESULTS

In addition to establishing that third molar agenesis was common during the Late Upper Paleolithic (22,500-10,000 years BP), this study suggests a pattern of increasing prevalence through time.

CONCLUSIONS

An increase in the prevalence of third molar agenesis in the Late Upper Paleolithic could indicate selection for dental size reduction and orthognathy, but also bio-cultural changes from more intensive food preparation techniques.

SIGNIFICANCE

Third molar agenesis, a well-known developmental defect, is often reported for recent human skeletal collections, but the prevalence of the condition for Pleistocene hominins had not been previously quantified in order to consider patterns through time. Hypotheses posited for the high prevalence of third molar agenesis, or hypodontia in general, in some recent human groups require an understanding of the prevalence of these traits in the past.

LIMITATIONS

Paleolithic skeletal remains are incomplete, so these values are under-estimations. Individuals are also separated diachronically and geographically and should not be assumed to represent a single population sample.

SUGGESTIONS FOR FURTHER RESEARCH

Hypotheses on some of the potential selective forces acting on dental size reduction and subsequent agenesis could be tested in recent humans.

Association between teeth agenesis and Angle's classes in an Italian population

BACKGROUND

Teeth agenesis or hypodontia consists of the developmental absence of one or more teeth. Many studies confirm that this condition is almost frequent in general population; the prevalence reported is between 2.7% and 11.3%. This condition shows a multifactorial etiology: genetic factors, hereditary factors, environmental factors, local or general infective processes, radiations, drugs and traumas. The aim of this observational study was to evaluate the prevalence of tooth agenesis in a sample of orthodontic healthy patients considering each Angle malocclusion.

METHODS

Nine hundred patients from a University clinic and three private practices were analyzed through intra and extra oral photographs, orthodontic study casts, panoramic radiographs and lateral cephalograms. The following inclusion criteria were applied: non-syndromic patients, without previous orthodontic, prosthetic treatment or extractions. Patients' clinical data consisted in general and dental anamnesis, intra and extra oral photographs, orthodontic study casts, digital panoramic radiographs and lateral cephalograms. The whole sample was divided into four groups (A-B-C-D) in relation with Angle's malocclusion and dental agenesis registered.

RESULTS

The whole sample presented a mean prevalence of the condition of 8.80%. Class II/2 is the most affected malocclusion with 20.37% of the patients affected by the condition, followed by class III (11.19%), class II/2 (8.05%) and class I (6.62%). The χ² test demonstrated a statistically significant different distribution of the condition between the four groups (P value =0.0059). The four groups presented also different patterns of missing teeth.

CONCLUSIONS

We found a significantly different distribution of the condition in the different malocclusions with class II/2 presenting the higher prevalence of tooth agenesis (20.37%). The most frequent teeth affected by agenesis in the entire sample are respectively: mandibular second premolars (32.40%), followed by the maxillary lateral incisors (27.70%) and the maxillary second premolars (15.50%).

Are developmentally missing teeth a predictive risk marker of malignant diseases in non-syndromic individuals? A systematic review

Background:

Different genes and loci that are associated with non-syndromic developmental tooth agenesis (TA) have the same causation pathway in the development of tumours including breast cancer (BC), epithelial ovarian cancer (EOC), colorectal cancer (CRC) and lung cancer (LC).

Objectives:

To assess the link between TA and the development of cancer.

Search sources:

This registered review included a comprehensive search of electronic databases (Cochrane Central Register of Controlled Trials [CENTRAL], LILACS, Scopus, Web of Science and Medline via Ovid) until 1 April 2020, supplemented by manual, grey literature and reference lists search. There was no restriction in term of date of publication, gender, race or type of hypodontia.

Data selection:

The primary outcome was the relationship between TA and cancer. The secondary outcome was to identify the genetic correlation between TA and cancer.

Data extraction:

Study selection, data extraction and risk of bias assessment were performed independently and induplicate by two reviewers, with disputes resolved by a third reviewer.

Results:

Eight studies with a moderate-high risk of bias were included in the final review, with a total of 5821 participants. Due to the heterogeneity among the included studies, the data were presented narratively. Limited studies reported a high prevalence of EOC (19.2%–20%) and CRC (82%–100%) in individuals with TA (depending on the study) compared to those without TA (3% for EOC and 0% for CRC). While others reported a weak correlation between EOC and CRC and TA ( P > 0.05). Weak evidence suggested a strong correlation between breast, cervical uterine and prostate cancers and TA ( P < 0.05).

Conclusions:

Though low-quality evidence suggests a link between TA and cancer, it was not possible to verify that TA can hold a predictive value as a marker for cancers. Further research is needed to confirm the association.

Registration:

PROSPERO (CRD42020139751).

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.

Space closure versus space opening for bilateral absent upper lateral incisors: what is the duration of orthodontic treatment?

BACKGROUND

Assessment of orthodontic treatment outcomes such as treatment duration in patients with hypodontia are lacking.

OBJECTIVES

To assess the overall treatment duration of cases of bilateral absent upper lateral incisors treated with either orthodontic space closure (SC) or space opening (SO). The secondary aim was to determine factors which influence overall treatment duration.

SUBJECTS AND METHODS

A retrospective cohort study was undertaken within the Orthodontic department at Kings College Hospital NHS Foundation Trust. Consecutively treated patients between 2008 and 2018 with bilateral absent upper lateral incisors were identified from clinic lists, clinical logbooks, and multidisciplinary clinics. All study data variables were collected by a single investigator using a pre-specified data collection sheet.

RESULTS

In total, 52 cases were included, 29 in the SC group and 23 in the SO group. Overall non-extraction treatment was favoured (P = 0.001) with differences in restorations provided post-treatment evident (P = 0.01). Although not statistically significant, the mean overall orthodontic treatment duration was less in the SC group 25.7 months (SD 7.6) compared to the SO group 27.4 (SD 6.1). Overall treatment duration was reduced if treatment was carried out on an extraction basis (-7.02, 95% CI: -11.93, 2.11, P = 0.01) but increased as the amount of crowding in the lower arch increased (0.89, 95% CI: 0.08, 1.71, P = 0.03).

CONCLUSIONS

Within the study limitations, there is no difference in the overall treatment duration between both treatment approaches. Treatment duration is reduced in both SO or SC treatment plans if extractions are undertaken. The presence of lower arch crowding increases the duration of treatment.

Dental development in patients with and without unilateral cleft lip and palate (UCLP): a case control study

OBJECTIVE

To evaluate if the presence of unilateral cleft lip and palate (UCLP) causes delay in dental age and tooth development.

MATERIALS AND METHODS

Panoramic radiographs of 189 non-syndromic UCLP patients, aged from 6 to 20 years, were collected. Two measures of tooth development were examined: dental maturity scale for the seven left mandibular teeth (dental age-DA) and the degree of each tooth development (developmental score-DS). All the teeth except third molars were staged according to the Demirjian's method. The data of the cleft group were compared with a control group matched for age and gender, based on the findings observed in other 189 panoramic radiographs.

RESULTS

At all ages, DA was lower in the UCLP group, but not always significantly; the highest difference was - 1.411 for females at 13 years old and - 0.776 for males at 12 years old. DS of all teeth was significantly lower in the UCLP group, at all ages under 17 in females, and at all ages under 18 in males. In UCLP group, tooth development was more delayed in the maxilla compared with the mandible. No evidence of a slower development at the cleft side compared with the non-cleft side was highlighted.

CONCLUSIONS

Significant lower dental development was observed in UCLP patients compared with control ones by using DS and DA indexes.

CLINICAL RELEVANCE

These findings can help the clinicians in establishing a proper orthodontic and surgical diagnosis and treatment planning in UCLP patients and for forensic age estimation's purposes.

Orthodontic management of patients with congenitally missing permanent teeth

Dental agenesis is one of the most common developmental anomalies in humans. It occurs as part of a genetic syndrome or as an isolated sporadic or familial finding. Third molars, second mandibular premolars and maxillary lateral incisors are the most frequently targeted teeth of the permanent dentition. Clinically, patients with congenitally missing permanent teeth seeking treatment present with unesthetic diastemas, midline deviation and tilting of adjacent teeth in the edentulous areas. The impact of tooth agenesis reflects on esthetics, function, psychological and social well-being of the individuals affected. Orthodontics can contribute to the treatment plan selected by rearranging the present teeth so as to open spaces for prosthetic restorations or close spaces by reshaping teeth if needed. Following orthodontic space opening/maintaining, the usual alternatives involve single implants, two-(cantilever) or full coverage(cantilever) prostheses. Less frequently, the treatment modality of autotransplantation is proposed with a good esthetic result but feasible only in young patients where the roots of the premolars are still developing. In orthodontic space closure, treatment is accomplished sooner without waiting for the completion of growth of the patient. Depending on various factors such as the malocclusion, the dento-skeletal profile, the smile line, the space requirements, the teeth missing, the periodontal issues, the age of the patient and any financial issues, the clinician will determine the most appropriate treatment approach. The final esthetic and functional result should resemble an intact natural dentition.

Prediction of agenesis of the maxillary second premolar based on the developmental stages of the maxillary canine, first premolar, and second molar

OBJECTIVE

This study aimed to suggest criteria for the early diagnosis of agenesis of the maxillary second premolars (U5) based on the developmental stages of the maxillary canines (U3), first premolars (U4), and second molars (U7).

DESIGN

Overall, 303 control patients and 72 patients with agenesis who met the inclusion criteria were analyzed among 5136 patients aged 5-11 years for whom panoramic radiographs were obtained at Seoul National University Dental Hospital from June 2008 to December 2009. All developmental stages of U3, U4, U5, and U7 in both groups were evaluated and categorized into the stages proposed by Demirjian et al. To confirm the delayed dental development in the agenesis group, the Wilcoxon rank sum test was used. For verifying the tooth with the most similar developmental pattern to U5, the Kendall tau Rank Correlation and Bootstrap methods were used. Moreover, survival analysis and leave-one-out-cross-validation were performed to identify the earliest developmental stages of U3, U4, and U7 at which agenesis of U5 can be confirmed.

RESULTS

The developmental stage of U4 in the agenesis group was significantly delayed compared with that in the control group at ages 5-10. All of the stages of U3, U4, and U7 showed high correlation coefficients with U5.

CONCLUSION

U5 agenesis can be confirmed with high prediction accuracy when at least two of the three conditions are satisfied: U3, U4, and U7 in Demirjian stages E, D, and C, respectively.

Interdisciplinary Approach to Treat Patients With Tooth Agenesis: A Case Report

INTRODUCTION

Tooth agenesis is a type of dental anomaly in which individuals are missing teeth due to developmental failure as a result of genetic or environmental factors. With approximately one fourth of the population missing ≥1 third molar, tooth agenesis is considered a common dental anomaly. However, the severity of tooth agenesis can range from a missing single tooth to multiple teeth. When suffering from severe tooth agenesis, the patient's health and social relationships are often affected.

CASE PRESENTATION

The patient in this report congenitally lost 11 teeth and suffered from compromised esthetics and impaired chewing function. In such a severe tooth agenesis case, interdisciplinary treatments involving orthodontics, periodontics, and prosthodontics were engaged to reconstruct the ideal biology, function, and esthetics for the patient. With an interdisciplinary approach, the periodontist played an important role in the rehabilitation of the edentulous regions with implants in combination with various hard and soft tissue augmentation procedures. In addition, the patient with severe tooth agenesis presented with additional dental anomalies. The periodontist, therefore, had to collaborate with other specialists to provide early detection and intervention to avoid future complications, such as the management of infraoccluded ankylosed deciduous molars and aberrant frenum. The patient at the end of treatment had a good occlusion with improved function and esthetics.

CONCLUSION

This case report describes the interdisciplinary treatment approach used and points out the role of periodontists in the treatment of a patient with severe tooth agenesis.

Management of patients with hypodontia: What has changed?

This review will consider changes in clinical practice associated with the management of patients with missing teeth and briefly review the evidence base that underpins what we do for them.

Mind the gap: A novel technique for space closure - a case report

Patients presenting with severe hypodontia can be challenging to manage. They often present with significant spaces within the dental arches and the lack of permanent teeth can make anchorage control difficult. This case report demonstrates a novel technique for diastema closure in a 14-year-old with severe hypodontia. The technique allows maintenance of root parallelism during space closure in cases with reduced anchorage support. The treatment plan was agreed on a multidisciplinary hypodontia clinic and involved an upper sectional fixed orthodontic appliance to close a 7-mm midline diastema aiding subsequent partial denture provision. Treatment commenced by bonding upper primary canines and central incisors. However, attempting space closure on a 0.019 × 0.025-inch stainless-steel working archwire resulted in tipping of the incisor crowns. Two brackets were therefore placed on the labial surface of each central incisor (one incisal and one gingival). Subsequently two stainless steel working archwires and elastomeric chain were used for diastema closure. This four-bracket system provided superior control allowing space closure by bodily tooth movement. Excellent root parallelism was achieved with this innovative technique.

Hypodontia and retention of third molars in Norwegian medieval skeletons: dental radiography in osteoarchaeology

OBJECTIVES

The objective of the present study is to compare the prevalence of third molar hypodontia in matched medieval and modern Norwegian sample with the aim to examine whether there are secular changes in dental anomalies. A second objective is to determine the level of primary retention of third molar in the medieval sample.

MATERIAL AND METHODS

The medieval material consisted of 130 adult skulls, hypodontia of third molars was determined using radiography and compared to findings with panoramic film images of 400 15-year-old individuals from a contemporary Norwegian epidemiological study.

RESULTS

Among 130 medieval skulls, hypodontia of third molar was found in 36 skulls (27.7%), and in the contemporary sample, hypodontia of third molar was found in 69 individuals (17.2%). Female predominance, although not statistically significant, was observed both in the medieval and in the contemporary group. The third molars showed absence in the mandible (21.5%) more often than the maxilla in the medieval sample, and in both jaws (11.2%) in the contemporary material. In the medieval sample, only 7.7% of the individuals had at least one retained third molar.

CONCLUSION

No increase in the frequency of third molar hypodontia was found from the medieval period until today. The frequency of retained third molars seems to have increased from the medieval period to modern times. The use of radiographic examination in addition to macroscopic inspection can give us a better understanding of the aetiology on a number of conditions in human skeletal remains.

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.

The role of PAX9 promoter gene polymorphisms in causing hypodontia: a study in the Jordanian population

Background

The congenital absence of one or few teeth, hypodontia, is considered one of the utmost dental ageneses in human beings. Several genes have been shown to be involved in the development of hypodontia such as paired box gene 9 (PAX9). The expression of PAX9 is controlled by several polymorphic elements in the promoter region of the gene on 14q13.3 locus. The aim of this study was to find any association between PAX9 c.-912T>C (rs2073247) and c.-1031G>A (rs2073244) promoter polymorphisms and the development of hypodontia among the Jordanian population.

Methods

Genotyping of the polymorphisms in 72 unrelated subjects with hypodontia was performed using PCR-restriction fragment length polymorphism (RFLP) technique and compared with that of 72 normal healthy unrelated control individuals.

Results

The hypodontia group had a significantly higher -1031GG genotype (P<0.01) and a significantly lower -912TC genotype (P<0.01) compared with the control group. The results suggest that the transcriptional activity of PAX9 gene is affected by polymorphisms in the promoter region of this gene and is associated with hypodontia phenotype.

Conclusion

The rs2073247) and rs2073244 promoter polymorphisms of PAX9 might play a role in the development of hypodontia in the Jordanian population.

Orthodontic Canine Substitution for the Management of Missing Maxillary Lateral Incisors May Have Superior Periodontal and Esthetic Outcomes Compared to an Implant- or Tooth-Supported Prosthesis

ARTICLE TITLE AND BIBLIOGRAPHIC INFORMATION

Prosthetic replacement vs space closure for maxillary lateral incisor agenesis: A systematic review. Silveira GS, Almeida NV, Pereira DMT, Mattos CT, Mucha JN. Am J Orthod Dentofacial Orthop 2016; 150(2):228-37.

SOURCE OF FUNDING

None listed TYPE OF STUDY/DESIGN: Systematic review.

32 and you - genetic testing for dental disorders

Genetic testing for serious illness and disease is becoming increasingly embedded in NHS healthcare. It can confirm a clinical diagnosis or guide therapy. Genetic testing for dental developmental disorders has moved beyond the realms of rarified grant-funded research groups and is now sufficiently rapid and affordable to be offered as part of a clinical service in some dental teaching hospitals. The first presentation of some genetic diseases may be in the dental surgery, so the family dentist should hone their diagnostic skills to identify patients who would benefit from referral to a genetics service. While diagnosis may sometimes guide treatment, there are now examples where it can even lead to cure. This article aims to describe some concepts and issues that a dentist should consider when referring for testing for a genetic dental disorder, and proposes that this subject area should be expanded in the dental undergraduate and postgraduate curricula in the UK.

A review on non-syndromic tooth agenesis associated with PAX9 mutations

Tooth agenesis in the reduction of tooth number which includes hypodontia, oligodontia and anodontia is caused by disturbances and gene mutations that occur during odontogenesis. To date, several genetic mutations that unlock the causes of non-syndromic tooth agenesis are being discovered; these have been associated with certain illnesses because tooth development involves the interaction of several genes for tooth epithelium and mesenchyme odontogenesis. Mutation of candidate genes PAX9 and MSX1 have been identified as the main causes of hypodontia and oligodontia; meanwhile, AXIN2 mutation is associated with anodontia. Previous study using animal models reported that PAX9-deficient knockout mice exhibit missing molars due to an arrest of tooth development at the bud stage. PAX9 frameshift, missense and nonsense mutations are reported to be responsible; however, the most severe condition showed by the phenotype is caused by haploinsufficiency. This suggests that PAX9 is dosage-sensitive. Understanding the mechanism of genetic mutations will benefit clinicians and human geneticists in future alternative treatment investigations.

Expressional Analysis of MSX1 (Human) Revealed its Role in Sagittal Jaw Relationship

INTRODUCTION

Abnormal skeletal jaw relationships is an important factor causing difficulty in speech, mastication, sleep and social interaction, thus affect the overall well being of an individual.

AIM

The present study was an attempt to decipher the role of human MSX1 in terms of sagittal jaw relationship by employing Polymerase Chain Reaction (PCR) based analysis.

MATERIALS AND METHODS

Ninety-eight case subjects belonging to North India with skeletal Class II and Class III jaw relationships were selected. Further, thirty-five control subjects of the same region having Class I skeletal and dental relationships (normal Jaw relationships) with good alignment of all teeth were enrolled. MSX1 gene sequencing was performed using the subjects' blood samples. Multiple sequence alignment was performed to find Single Nucleotide Polymorphisms (SNP's). Nine SNP's were obtained of which seven were reported and two novels. Statistical analysis was performed using Chi square test to compare genotype differences between case and control groups.

RESULTS

SNP rs186861426 was found to be significantly associated in Class I subjects (p-value=0.02). The sequencing results suggested that individuals having changes from G (guanosine) with A (adenine) genotype had approximately seven times low risk for developing Class II division 1 malocclusion as compared to those alleles having GG genotype and therefore, allele 'A' position on chromosome 4 (rs186861426) seems to have a protective role.

CONCLUSION

The study unfolds an important relationship between MSX1 gene and Class II division 1 malocclusion and Class I normal skeletal relationships. The study tried to interpret the role of human MSX1 and extend the gene pool responsible for the skeletal anomalies related to development of abnormal upper and lower jaws.

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.

Hypodontia: An Update on Its Etiology, Classification, and Clinical Management

Hypodontia, or tooth agenesis, is the most prevalent craniofacial malformation in humans. It may occur as part of a recognised genetic syndrome or as a nonsyndromic isolated trait. Excluding third molars, the reported prevalence of hypodontia ranges from 1.6 to 6.9%, depending on the population studied. Most affected individuals lack only one or two teeth, with permanent second premolars and upper lateral incisors the most likely to be missing. Both environmental and genetic factors are involved in the aetiology of hypodontia, with the latter playing a more significant role. Hypodontia individuals often present a significant clinical challenge for orthodontists because, in a number of cases, the treatment time is prolonged and the treatment outcome may be compromised. Hence, the identification of genetic and environmental factors may be particularly useful in the early prediction of this condition and the development of prevention strategies and novel treatments in the future.

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.

Occlusal features and need for orthodontic treatment in persons with osteogenesis imperfecta

The aim of the study was to (a) analyse dental occlusion and determine the need for orthodontic treatment of persons with osteogenesis imperfecta (OI) in comparison with the healthy population and (b) investigate the associations between OI and malocclusion. A case-control study included 26 OI persons and 400 healthy participants (control group). Occlusal features and the need for orthodontic treatment were defined according to Dental Health Component-Index of Orthodontic Treatment Need and Dental Aesthetic Index. Results showed that Angle Class I, II, and III relationship was found in 23.1%, 3.8%, and 73.1% of OI group, and in the control group, it was 67%, 17.5%, and 15.5%, respectively. OI group had significantly higher prevalence of reverse overjet >1 mm (76.9%), missing teeth (42.3%), posterior crossbite (34.6%), and open bite >2 mm (19.2%) compared to the control group (8.5%, 2.2%, 6.2%, and 3.5%, respectively). OI group had less incisal segment crowding and more incisal segment spacing than the control group (p < 0.05). The need for orthodontic treatment of OI group according to Dental Health Component-Index of Orthodontic Treatment Need and Dental Aesthetic Index was 88.5% and 61.5%, respectively, while in the control group, it was 24.8% and 51.8%. The malocclusion in OI persons was associated with reverse overjet > 1 mm (OR = 13.3, 95% CI = 3.9-44.7, p < .001), Angle Class III malocclusion (OR = 8.0, 95% CI = 2.0-30.8, p = .003), and missing teeth (OR = 4.7, 95% CI = 1.0-22.4, p = .049). In conclusion, there is the high probability of malocclusion in OI persons. Persons with OI require early orthodontic treatment because of significant correlation of OI disease with Angle Class III malocclusion, reverse overjet, and missing teeth.

Study of alveolar ridge dimensions before and after orthodontic treatment in maxillary lateral incisor agenesis: A pilot study

The objective of this study was to compare the dimensional changes in the alveolar ridge before, at the end of, and one year after orthodontic treatment in cases of Maxillary Lateral Incisor Agenesis and the possibility of using plaster models and panoramic radiographs as substitutes for cone beam-computed tomography.

MATERIAL AND METHODS

A total of 228 measurements were performed on plaster models and panoramic radiographs: before (T1), at the end of (T2), and 1 year after orthodontic treatment (T3). At stage T2, the cone beam-computed tomography was also analyzed. Non-parametric tests were used.

RESULTS

In all 3 stages, there was no statistically significant difference regarding the thickness of the models, the height of the bone in the panoramic radiographs, the space opening and the height of the bone in the panoramic radiographs, or the space opening in the models and the thickness in the same plaster models. However, a statistically significant difference was observed for the width in the panoramic radiograph during all 3 stages. Cone beam-computed tomography did not reveal a statistically significant correlation regarding the height and width of the bone compared with the panoramic radiographs, and the thickness as compared with plaster models.

CONCLUSION

There was no significant variation in thickness, height and width of the bone over time. It was demonstrated that plaster models and panoramic radiographs do not appear to be good substitutes for cone beam-computed tomography for these specific measurements.

Evaluation of the orthodontic component of the hypodontia care pathway

INTRODUCTION

This study evaluated patients' experiences of the Hypodontia Care Pathway at a large teaching hospital at key stages: specifically patient expectations/experience following the diagnosis of hypodontia and then patient satisfaction with the orthodontic care received and the outcome at the end of active orthodontic treatment.

METHODOLOGY

In-depth, semi-structured interviews were conducted with 20 hypodontia patients following completion of orthodontic treatment but prior to any planned prosthodontic treatment commencing. Interviews were analysed qualitatively, using a framework approach.

RESULTS

The framework analysis identified four main themes: perceptions of treatment, impact of the original malocclusion and the treatment process, the care team and communication. The themes were then further divided into subthemes.

DISCUSSION

There was a large amount of positive feedback and the importance of the patient-clinician relationship was evident throughout. Where issues of concern were identified, these related mainly to communication and areas were identified where change could take place in the future.

CONCLUSIONS

Positive feedback was received and the importance of patient-clinician rapport was highlighted in all interviews. The main areas that could be enhanced related to the importance of ensuring optimum communication, particularly with a cohort of patients who are often undergoing complex multidisciplinary treatment. Recommendations for the service have been made.

Dental Anomalies in a Brazilian Cleft Population

Objective

The aim of this study was to radiographically investigate the prevalence of dental anomalies outside the cleft area in a group of Brazilian patients with nonsyndromic cleft lip and/or palate (NSCL/P).

Design, Participants, and Setting

A retrospective analysis of 207 panoramic radiographs of patients with NSCL/P aged 12 to 45 years without history of tooth extraction and orthodontic treatment was performed.

Results

Dental anomalies were found in 75.4% of the patients, and tooth agenesis (29.2%) and supernumerary tooth (2.6%) were the most common anomalies. The risk of agenesis was higher among the individuals with cleft palate (CP) compared with individuals with cleft lip (CL) and cleft lip and palate (CLP) (agenesis: CP versus CL: odds ratio 6.27, 95% confidence interval 2.21-17.8, P = .0003; CP versus CLP: odds ratio 2.94; 95% confidence interval 1.27-6.81, P = .01). The frequency of dental agenesis was higher in patients with unilateral complete CLP (agenesis: P < .0001), incomplete bilateral CLP (agenesis: P = .0013), complete CP (agenesis: P < .0001), and incomplete CP (agenesis: P < .0001). The frequency of supernumerary teeth was higher in patients with bilateral complete CLP ( P < .0001). The frequency of dental agenesis ( P < .0001) and ectopic tooth ( P = .009) was higher than the frequency estimated for general population.

Conclusions

The prevalence of dental anomalies in patients with NSCL/P was higher than that reported in overall population. This study found preferential associations between dental anomalies and specific extensions of NSCL/P, suggesting that dental agenesis and ectopic tooth may be part of oral cleft subphenotypes.

Prevalence of delayed tooth development and its relation to tooth agenesis in Korean children

OBJECTIVE

The aim of this study was to investigate the epidemiology of delayed tooth development (DTD) and the link between DTD and tooth agenesis (TA).

DESIGN

The dental maturity of all of the developing permanent teeth of 4611 children (2417 males and 2194 females) was evaluated from panoramic radiographs. The prevalence of DTD and TA was analyzed, and gender difference for DTS and TA was investigated. The correlation of DTD and TA was investigated in intra-fields and inter-fields.

RESULTS

The total prevalence of DTD among the 4611 children was 3.40%. The maxillary second premolar was the most frequently delayed tooth (1.02%), followed by the maxillary second molar (0.88%) and the mandibular second premolar (0.74%). DTD significantly correlated with TA in both intra-fields and inter-fields (p<0.05).

CONCLUSIONS

The field of delayed development exhibited a significant correlation with that of TA.

The association between WNT10A variants and dental development in patients with isolated oligodontia

In this study we aimed to determine the effect of WNT10A variants on dental development in patients with oligodontia. Forty-three (25 boys and 18 girls) individuals were eligible for this study. Stage of development for each present tooth was assessed using the Demirjian method. In case no corresponding tooth was present, regression equations were applied for dental age to be calculated. The ratio between length of root and length of crown was ascertained for each present tooth in all quadrants. All patients were physically examined by a clinical geneticist and DNA analysis of the WNT10A gene was performed. Linear regression models were applied to analyze the association between WNT10A variants and dental age. The same analysis was applied to study the association between WNT10A variants and root elongation for each present tooth. One ordinal regression model was applied to analyze the association between WNT10A variants and development of present maxillary and mandibular teeth. Thirty-six (84%) patients were detected with WNT10A variants of which six patients displayed evident ectodermal features. Dental age was 1.50 (95% confidence interval (CI): -2.59, -0.42) to 1.96 (95% CI: -3.76, -0.17) years lower in patients with WNT10A variants compared with patients without variants. The development of maxillary canine, maxillary second molar and mandibular second molar was statistically significantly delayed in patients with WNT10A variants compared with patients without variants. The impact of WNT10A variants on dental development increases with presence of the nonsense c.(321C>A p.(C107*)) variant and the number of missing teeth.

Mutation analysis by direct and whole exome sequencing in familial and sporadic tooth agenesis

Dental agenesis is one of the most common congenital craniofacial abnormalities. Dental agenesis can be classified, relative to the number of missing teeth (excluding third molars), as hypodontia (1 to 5 missing teeth), oligodontia (6 or more missing teeth), or anodontia (lack of all teeth). Tooth agenesis may occur either in association with genetic syndromes, based on the presence of other inherited abnormalities, or as a non-syndromic trait, with both familiar and sporadic cases reported. In this study, we enrolled 16 individuals affected by tooth agenesis, prevalently hypodontia, and we carried out direct Sanger sequencing of paired box 9 (PAX9) and Msh homeobox 1 (MSX1) genes in 9 subjects. Since no mutations were identified, we performed whole exome sequencing (WES) in the members of 5 families to identify causative gene mutations either novel or previously described. Three individuals carried a known homozygous disease mutation in the Wnt family member 10A (WNT10A) gene (rs121908120). Interestingly, two of these individuals were siblings and also carried a heterozygous functional variant in EDAR-associated death domain (EDARADD) (rs114632254), another disease causing gene, generating a combination of genetic variants never described until now. The analysis of exome sequencing data in the members of other 3 families highlighted new candidate genes potentially involved in tooth agenesis and considered suitable for future studies. Overall, our study confirmed the major role played by WNT10A in tooth agenesis and the genetic heterogeneity of this disease. Moreover, as more genes are shown to be involved in tooth agenesis, WES analysis may be an effective approach to search for genetic variants in familiar or sporadic tooth agenesis, at least in more severe clinical manifestations.

Dental development in patients with agenesis

AIM

Recent research concerning tooth development and dental agenesis suggests that specific genes are associated with agenesis, and that these genetic factors could also cause delayed dental development of the remaining teeth. The objective of this study was to evaluate whether dental development of patients with agenesis is delayed, compared to a control group.

SUBJECTS AND METHOD

Panoramic radiographs of 1145 patients with dental agenesis were collected (452 males, 693 females) aged 6.2 to 24.8 years. The control group included 2032 panoramic radiographs (977 males, 1055 females) aged 6.0 to 24.4 years. A total of 3177 orthopantomograms were staged according to Demirjian. All left permanent teeth present in the mandible (except third molars) were considered. In order to evaluate the difference between patients with and without agenesis, a developmental score (DS) was calculated. The association between the DS and the number of agenetic teeth was evaluated with a Spearman correlation.

RESULTS

Based on the DS, patients with agenesis have a delayed development compared to patients in the control group (p < 0.0001). Within the agenesis group, there is a weak relation between the number of agenetic teeth and the DS: the higher the number of teeth with agenesis, the lower the DS (p < 0.0001 and p = 0.06 for females and males, respectively).

CONCLUSION

The obtained results can be an important factor for treatment planning in patients with dental agenesis. Moreover, the presence of agenesis needs to be taken into account when using age estimation methods based on permanent tooth development.

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.

The association between hypodontia and dental development

OBJECTIVES

In this cross-sectional study, we aimed to investigate the pattern of hypodontia in the Dutch population and determine the association between hypodontia and dental development in children with and without hypodontia, applying three different standards, Dutch, French Canadian, and Belgian, to estimate dental age.

METHODS

We used dental panoramic radiographs (DPRs) of 1488 children (773 boys and 715 girls), with a mean age of 9.76 years (SD = 0.24) participating in a population-based cohort study in Rotterdam, the Netherlands, born in 2002-2004, and 452 children (219 boys and 233 girls) with a mean age of 9.83 years (SD = 1.09) participating in a mixed-longitudinal, interdisciplinary population-based cohort study in Nijmegen, the Netherlands born in 1960-1968.

RESULTS

The prevalence of hypodontia in the Generation R Study was 5.6 % (N = 84) and 5.1 % (N = 23) in the Nijmegen Growth Study. Linear regression analysis showed that children with hypodontia had a 0.37 [95 % CI (-0.53,-0.21)] to 0.52 [95 % CI (-0.76,-0.38)] years lower dental age than children without hypodontia. The ordinal regression analysis showed a delay in development of mandibular second premolars [1.68 years; 95 %CI (-1.90,-1.46)], mandibular first premolars [0.57 years; 95 % CI (-0.94,-0.20)], and mandibular second molars [0.47 years; 95 % CI (-0.84,-0.11)].

CONCLUSION

These findings suggest that children with hypodontia have a delayed dental development.

CLINICAL RELEVANCE

The delay of dental development in children with hypodontia should be taken into consideration and therefore orthodontists should recognize that a later start of treatment in these patients may be necessary.