Radiographic evaluation of third molar development in 6- to 24-year-olds

Correlations of spheno-occipital synchondrosis, cervical vertebrae, midpalatal suture, and third molar maturation stages

OBJECTIVES

To estimate the joint correlations among cervical vertebrae maturation (CVM), spheno-occipital synchondrosis (SOS), midpalatal suture maturation (MPS), and third molar mineralization (TMM) and to assess the predictive potential of SOS on CVM and MPS.

MATERIALS AND METHODS

570 pretreatment cone-beam computed tomogram (CBCT) scans from three private practices were analyzed, and MPS, CVM, SOS, and TMM stages were categorized and recorded by two independent investigators. Intra- and inter-rater reliability tests were evaluated with weighted Cohen's kappa tests. Spearman correlation coefficients for ordinal data were used to estimate the pairwise correlations among SOS, CVM, MPS, and TMM. To evaluate if SOS could predict CVM and MPS, ordinal regression models were estimated and cross-validated.

RESULTS

The analysis demonstrated a robust positive correlation between SOS and CVM (r = 0.845) and between SOS and MPS (r = 0.742). A significant correlation was also observed between CVM and MPS (r = 0.659). Further correlations were identified between TMM and SOS (r = 0.444), TMM and MPS (r = 0.392), and TMM and CVM (r = 0.358). Ordinal regression models indicated the potential of using SOS as a predictive marker for CVM and MPS stages.

CONCLUSIONS

With a comprehensive analysis, SOS is strongly correlated with CVM and MPS, and SOS stage can be used to predict CVM and MPS using ordinal regression. Since MPS stages are challenging to categorize due to their anatomy, this finding suggests a diagnostic tool using SOS stages or when more information on skeletal maturity of the patient is desired.

Association between craniofacial patterns and third molar agenesis in orthodontic patients

PURPOSE

Third molar agenesis (TMA) is the most common craniofacial anomaly and has been associated with craniofacial patterns in different populations. Therefore, the aim of this retrospective cross-sectional study was to assess a possible association between craniofacial patterns and TMA in German orthodontic patients.

METHODS

Patients undergoing orthodontic treatment with dental records including anamnesis, pretreatment lateral cephalograms and orthopantomograms were evaluated. Cephalometric analyses were conducted digitally and lines, angles and proportions were measured to investigate craniofacial morphology. Skeletal classes were determined by the individualised Wits appraisal and ANB angle. The TMA was identified with the help of orthopantomograms. Patients showing agenesis of at least one third molar were included in the TMA group. Statistical analysis was performed to assess the association between TMA and craniofacial patterns (α of p ≤ 0.05).

RESULTS

A total of 148 patients were included, 40 (27.0%) presented at least one missing tooth (TMA group) and 108 (73.0%) showed full dentition (control group). Skeletal class determined by the individualised Wits appraisal revealed statistical significance between the TMA and control groups (p = 0.022), in which TMA patients were 11 times more likely to present with an individualised skeletal class III (odds ratio 11.3, 95% confidence interval 1.7-139.5). Skeletal cephalometric analysis revealed no statistical differences between TMA and control groups for any further angular, linear and proportional parameters.

CONCLUSION

Third molar agenesis was associated with skeletal class III determined by the individualised Wits appraisal.

From Pluripotent Stem Cells to Organoids and Bioprinting: Recent Advances in Dental Epithelium and Ameloblast Models to Study Tooth Biology and Regeneration

Ameloblasts are the specialized dental epithelial cell type responsible for enamel formation. Following completion of enamel development in humans, ameloblasts are lost and biological repair or regeneration of enamel is not possible. In the past, in vitro models to study dental epithelium and ameloblast biology were limited to freshly isolated primary cells or immortalized cell lines, both with limited translational potential. In recent years, large strides have been made with the development of induced pluripotent stem cell and organoid models of this essential dental lineage - both enabling modeling of human dental epithelium. Upon induction with several different signaling factors (such as transforming growth factor and bone morphogenetic proteins) these models display elevated expression of ameloblast markers and enamel matrix proteins. The advent of 3D bioprinting, and its potential combination with these advanced cellular tools, is poised to revolutionize the field - and its potential for tissue engineering, regenerative and personalized medicine. As the advancements in these technologies are rapidly evolving, we evaluate the current state-of-the-art regarding in vitro cell culture models of dental epithelium and ameloblast lineage with a particular focus toward their applicability for translational tissue engineering and regenerative/personalized medicine.

Age Estimation of Children and Young Adults of Jharkhand Using Mineralization of Third Molars and Its Relation to Chronological Age: A Retrospective Analysis

Background Dental age estimation plays an enormous role in the determination of an individual's identity and age in forensic and anthropological fields. The estimation of the chronological age of the individual is also important in the diagnosis, treatment planning, and treatment outcomes in the dental field. The third molar has some inimitable characteristics in terms of its size, shape, formation, and long path of eruption and usually erupts after puberty, which seems to be a reliable method of age estimation in adulthood. To establish the individual's identity, inference of age has gained considerable attention in forensics, and the aspect of dentistry has broadened nowadays. Thus the present study was conducted. Methodology The digital orthopantomograms of 720 patients who were exposed to X-rays for routine examination were assessed, and calcification of the tooth was observed. In order to ensure the blinding of the examiners, radiographs were numerically coded. Clinical stages of the tooth were categorised into erupted, pre-erupted, and missing. Statistical analysis was performed by IBM SPSS Statistics for Windows, Version 25.0 (IBM Corp., Armonk, NY), with a level of significance set below 5%. Results The age of the patients whose OPGs were assessed ranged from 6 to 22 years, with a mean age of 18.93±3.129 years. Among the 720 participants, 370 (51.4%) were male and 350 (48.6%) were female. When the clinical status of the third molar among all the participants was assessed, in 148 (20.6%) subjects, third molars had erupted; in 188 (26.1%) subjects, the third molars were in the pre-erupted stage; and in 384 (53.30%), third molars were missing. When comparing the clinical status of the third molar in both arches and between genders, it was found that missing molars were common in females and the mandible arch, with statistically significant p-values. A comparison of Demirjian's stages between genders showed that the mean age to attain stage H was 21.37±0.774 years among males and 21.69±0.616 years among females. This means that the calcification of third-molar attainment occurs earlier in males compared with females. In a similar comparison between the upper and lower arches, it was found that calcification of the third molar was attained earlier in the maxillary arch compared to the mandibular arch. Conclusion It was concluded that the third molar is a versatile tooth and its path of mineralization can be used in orthodontics, pedodontics, and forensics to estimate chronological age, and chronological age significantly follows Demirjian's stages of third molar calcification. Third molar calcification occurred earlier in the maxillary arch and males, whereas several impacted molars were higher in females.

Agenesis of third molar among the younger population of India born in twenty first century

Objectives

The objective of this study was to find the prevalence of agenesis of third molar among the younger population of India.

Materials and Methods

A cross-sectional study was conducted, and a younger population (13-21 years) born in the twenty-first century were included. Individuals who required an orthopantomogram, for any reason, were recruited in the study.

Results

A total number of 850 orthopantomograms were studied, and 298 (35.05%) individuals showed the agenesis of at least 1 or more third molars. The most common pattern of agenesis was the missing of both maxillary third molars, followed by the agenesis of all third molars. The frequency of agenesis was 18 >28 >48 >38. The study showed a significant predilection in the maxilla as compared to the mandible. There was no statistically significant gender predilection for agenesis of third molar.

Conclusion

The prevalence of third molar agenesis is increasing rapidly with time, with no significant gender predilection and changing trends of patterns of agenesis.

Relationship between the Status of Third Molars and the Occurrence of Dental and Periodontal Lesions in Adjacent Second Molars in the Polish Population: A Radiological Retrospective Observational Study

The aim of this study was to evaluate the effect of third molars on caries, external root resorption, and alveolar bone loss on the distal surface of adjacent second molars. A total of 2488 panoramic radiographs of adult Poles were evaluated. Third molars were classified, according to eruption status, into non-impacted, partially, or completely impacted, and according to angulation into horizontal, mesioangular, vertical, and distoangular. Completely impacted third molars were assigned as reference group. The odds ratios (ORs) and 95% confidence intervals for the occurrence of the above-mentioned pathologies were 1.39 (1.09-2.21), 6.51 (3.72-10.11), and 2.42 (1.22-4.09), respectively, for second molars with adjacent erupted third molars and 1.54 (1.11-2.82), 10.65 (7.81-20.19), and 5.21 (3.38-10.81), respectively, when partially impacted third molars were next to second molars. The ORs of lesions were significantly higher for horizontally and mesioangularly impacted third molars. Within the limitation of a radiological study, it might be concluded that the presence of erupted third molars is a risk factor for caries, while the presence of impacted third molars increases the risk of root resorption and bone loss on the distal surface of second molars.

Assessment of the mineralisation stages of third molars and validation of Mincer et al.'s age estimation method: A retrospective, cross-sectional study in Western India population

Context

Age estimation is one of the prime requisites in forensic human identification cases and the criminal justice system. There are several age estimation methods using dental parameters. A method proposed by Mincer et al. which uses the mineralization stages of third molars based on Demirjian's developmental stages is less tested in the Indian population.

Aim

The present study aimed to assess the developmental status of the third molars and to apply and validate Mincer et al.'s method on the Western India population.

Methods and Material

A total of 306 orthopantomograms (OPGs) from 128 males and 178 females with a mean age of 16.89 years ± 3.68 were analysed. Demirjian's A-H staging was applied to record the developmental stages of 1100 third molars. Mincer et al.'s mean age of attainment was applied based on the American Whites (Caucasian) population for males and females separately using stages of #18 and #38.

Results

There was a slight overestimation of the chronological age (CA) in both #18 and #38. The females showed more accurate estimated age (EA) than males.

Conclusions

Mincer et al.'s method is a convenient age estimation method using the third molar's developmental stage. The mean age of attainment mentioned in the original Mincer et al.'s study can be used in the Western Indian population, with a residual value ranging from 0.21 to 0.25 years.

Criteria for early diagnosis of mandibular third molar agenesis based on the developmental stages of mandibular canine, first and second premolars, and second molar: a retrospective cohort study

BACKGROUND

Permanent first molars with severe dental caries, developmental defects, or involved in oral pathologies are at risk of poor prognosis in children. Accordingly, using the third molar to replace the first molar can be a good treatment option when third molar agenesis is predicted early. Thus, this retrospective cohort study aimed to develop criteria for early detection of mandibular third molar (L8) agenesis based on the developmental stages of mandibular canine (L3), first premolar (L4), second premolar (L5), and second molar (L7).

METHOD

Overall, 1,044 and 919 panoramic radiographs of 343 males and 317 females, respectively, taken between the ages of 6 and 12 years were included. All developmental stages of L3, L4, L5, L7, and L8 were analyzed based on the dental age, as suggested by Demirjian et al. The independent t-test was used to assess age differences between males and females. The rank correlation coefficients were examined using Kendall's tau with bootstrap analysis and Bonferroni's correction to confirm the teeth showing developmental stages most similar to those of L8s. Finally, a survival analysis was performed to determine the criteria for the early diagnosis of mandibular third molar agenesis.

RESULTS

Some age differences were found in dental developmental stages between males and females. Correlation coefficients between all stages of L3, L4, L5, and L7 and L8 were high. In particular, the correlation coefficient between L7 and L8 was the highest, whereas that between L3 and L8 was the lowest.

CONCLUSION

If at least two of the following criteria (F stage of L3, F stage of L4, F stage of L5, and E stage of L7) are met in the absence of L8 crypt, agenesis of L8 can be confirmed.

The Effect of Third Molars on the Mandibular Anterior Crowding Relapse-A Systematic Review

The present systematic review updates the evidence on wisdom teeth contributing to lower incisor crowding following orthodontic treatment. Relevant literature was searched on online databases, namely Pubmed, Scopus, and Web of Science, up to December 2022. Eligibility criteria were formulated using the PICOS approach and PRISMA guidelines. Eligible research included original clinical studies involving patients previously being treated orthodontically with permanent dentition at the end of treatment, regardless of sex or age. The initial search yielded 605 citations. After considering eligibility criteria and removing duplicates, only 10 articles met the criteria for inclusion. The risk of bias of eligible studies was evaluated using the Cochrane Handbook for Systematic Reviews and Interventions tool. The majority were highly biased, mainly regarding allocation concealment, group similarity, and assessment blinding. The vast majority did not report statistically significant associations between the presence of third molars and crowding relapse. However, a minor effect has been suggested. Seemingly, there is no clear connection between mandibular third molars and incisor crowding after orthodontic treatment. The present review did not find adequate evidence to advocate preventative removal of the third molars for reasons of occlusal stability.

Accuracy of age estimation and assessment of the 18-year threshold based on second and third molar maturity in Koreans and Japanese

This study aimed to validate Lee’s age estimation method and assess the 18-year threshold in Korean and Japanese populations. We evaluated the maxillary and mandibular second (M2) and third molars (M3) in 2657 orthopantomograms of the Korean and Japanese populations aged 15–23 years (19.47±2.62 years for Koreans, 19.31±2.60 years for Japanese), using Demirjian’s criteria. Dental age was estimated, and correlations between chronological and dental ages were analyzed. Classification performance was calculated based on the 18-year threshold. The relationship between developmental stage and chronologic age was analyzed using multiple linear regression. Our results revealed that Lee’s method was appropriate for estimation in the Korean population. When the Lee’s method was applied to the Japanese population, a lower value of correlation coefficients between estimated and chronological age, and lower specificity were observed. Population differences were observed predominantly in the stages of root development (stages F and G) of M2s and M3s in both jaws and more frequently in females than in males. In the multiple linear regression between developmental stage and chronological age, lower values of adjusted r² were observed in the Japanese population than in the Koreans. In conclusion, the Lee’s method derived from the Korean population data might be unsuitable for Japanese juveniles and adolescents. To support the findings of this study, future studies with samples from multiple institutions should be conducted. Future studies with larger sample sizes are also warranted to improve the accuracy of dental age estimation and confirm the developmental pattern of teeth in the Japanese population.

Clinical Indications to Germectomy in Pediatric Dentistry: A Systematic Review

Germectomy is a procedure often required in patients at developmental age. It is defined as the surgical removal of the third molar at a very specific stage of development. The aim of this study was to systematically analyze the literature in terms of clinical indications for germectomy in patients at developmental age. Literature searches were performed using PubMed, Google Scholar, Cochrane Library and Scopus from 1952 to 30 June 2021. The study protocol was registered after the screening stage (PROSPERO CRD42021262949). The search strategy identified 3829 articles: 167 from PubMed, 2860 from Google Scholar, 799 from Cochrane Library and 3 from Scopus. Finally, eight full-text papers were included into the qualitative analysis. Based on the included studies, clinical indications for germectomy were mainly related to orthodontic causes, infectious and cariogenic causes and prophylaxis. Based on these results, it is not possible to present evidence-based clinical indications for germectomy in patients at developmental age. Clinical trials on this subject focused specifically on patients at developmental age are awaited.

Testing international techniques for the radiographic assessment of third molar maturation

BACKGROUND

To assess the radiographic third molar maturation with internationally developed techniques for age estimation.

MATERIAL AND METHODS

The study analyzed 1,062 panoramic radiographs of patients treated at the School of Dentistry of the University of Passo Fundo/RS/Brazil, between 2009 and 2020. The patients were separated into ages between 15.00 and 23.99 years and, for each radiograph, the third molars were classified into stages from 1 to 10, with the subsequent application of one of the formulae proposed by Gunst et al. A dichotomous variable indicating whether each individual was younger or older than 18 was calculated from the chronological age of the individuals. A logistic regression model was adjusted to assess whether the third molar stages are correlated with the age of individuals.

RESULTS

The error indicators between estimated and chronological ages showed that mean errors closer to zero are seen in the 18-18.9 and 17-17.9 age groups, respectively. Male individuals were earlier in terms of dental mineralization but there were no significant differences between sexes regarding the applicability of the method. The ROC curve shows that the analysis of a single third molar for age estimation gives a maximum of 70.4% reliability.

CONCLUSIONS

The moderate performance of the technique tested in the present study justify future country-specific corrections to improve age estimation from the radiographic assessment of third molar maturity. Key words:Dental age estimation, forensic dentistry, radiology, third molar.

Age estimation from developing third molars

We investigated the development of third molars among Malaysians (including variations between jaws and genders) using Demirjian's method. Dental panoramic radiographs of 1224 subjects aged 8 to 24 years were examined, and the molars were assigned Demirjian et al.'s development grades (A-H). Results indicated that 18.8% had congenitally missing or extracted third molars. Development of molars begins earlier in females (also in the mandible), but by age 9, male children's molar development speeds up with more advanced grades in their middle teens than females. Grade C indicates the subject is a juvenile, while initiation of root development (Grade E), was observed from 13 years on. Grade H can occur in a child aged 18 years who technically is still a juvenile. We compared the development and growth patterns of the third molar from both the maxilla and the mandible.

Chronological Age Assessment Based on the Root Pulp Visibility in Lower Third Molars in a Group of Thai Population: Panoramic Radiographic Study

Background:

Radiographic visibility of the root pulp in lower third molars is one of the reliable methodologies for chronological age estimation.

Objective:

To evaluate the radiographic visibility of the lower third molar root pulp using digital panoramic radiographs of the Thai population, and determine the appropriation of this technique in age assessment, especially at the age of 18 years.

Methods:

A total of 746 digital panoramic radiographs of the Thai population aged from 16 to 26 years were recruited for the present study. The visibility of root pulp of lower third molars with completed root formation was recorded in the four stages. Descriptive statistics were performed for each stage in both males and females.

Results:

The first appearance of stage 0 is 16.71 years in males and 17.00 years in females. The minimum age of stage 1 was found at 17.08 years in males and 17.18 years in females. The beginning of stage 2 was 18.33 years in males and 18.17 years in females. For stage 3, the earliest presence was started at 18.58 years in males and 18.83 years in females.

Conclusion:

The occurrence of stages 2 or 3 in both males and females indicated that the subject is over 18 years of age. Further study on the Thai population should be conducted to confirm the results of the present study.

Sensitivity and Specificity of Mandibular Third Molar Calcification at Chronological Age and Hand Wrist Maturation Stage to Discriminate Between Female and Male at Pubertal Growth Period

Background:

The mandibular third molar is the last tooth that is not completely developed by the time pubertal growth has been finished. Maturation of the mandibular third molar is one of the physiological maturation indicators that can be used to determine the stage of pubertal growth.

Objective:

The aim of the study was to determine the sensitivity and specificity of mandibular third molar calcification at chronological age and hand wrist maturation stage to discriminate between female and male at pubertal growth period.

Methods:

It is a retrospective study with a cross-sectional approach using panoramic and hand-wrist digital radiographs of 279 females and 144 males, age 8-17 years, with a total of 423 panoramic radiographs and 423 hand-wrist radiographs. Statistical analysis was performed using Excel Mega Stat. ANOVA to analyze the differences between mandibular third molar calcification at chronological age and hand-wrist maturation stage, and t-test was used to analyze the differences between females and males. Spearman rank correlation was used for the analysis of the correlation between mandibular third molar calcification with chronological age and hand-wrist maturation stage; sensitivity and specificity were used to discriminate the pubertal growth period between mandibular third molar calcification and hand-wrist maturation stage.

Results:

There were significant differences found in mandibular third molar crown maturation stage B and C, but no significant difference was observed between mandibular third molar stage A, D, E, F, G and H, between females and males. The highest percentage of mandibular third molar crown formation in females was observed at stage D (6.68%) at MP3u, and in males, it was observed at stage D (8.83%) at SMI-4. The highest percentage of root formation in females was stage E (8.24%) at the SMI-10 stage, and males stage F (4.86%) at MP3u. The correlation was observed between mandibular third molar calcification with hand-wrist, females 0.22 and males 0.43, and chronological age 0.60 for females and 0.69 for males. The highest sensitivity of mandibular third molar calcification of 97.0% was observed in female at SMI-4 of hand-wrist maturation with specificity of 100%, while in male, a sensitivity of 94.5% was observed at SMI-2 stage with a specificity of 99.99%.

Conclusion:

There were significant differences found in mandibular third molar calcification between females and males except for stage B and stage C; weak correlation was observed between mandibular third molar calcification and hand-wrist, and moderate correlation was observed with chronological age. The sensitivity and specificity in females and males indicate that mandibular third molar calcification is only useful for diagnosing the pre-pubertal growth phase.

Radiographic evaluation of non-syndromic third molar agenesis in two Mediterranean populations

Background and aims

Third molar agenesis is a common finding across the world. Many studies have assessed third molar agenesis in different ethnicities and populations. However, there are no such studies in the Italian and Lebanese populations. Our study aims to evaluate the prevalence of third molar agenesis and study the pattern and distribution of agenesis in between genders in Italian and Lebanese Mediterranean populations and compare these findings with other global and Mediterranean populations' studies.

Methods

Retrospective chart review was conducted based on the history and orthopantomograms of adolescents aged 12 to 21 years to assess the agenesis of third molars in a sample of Italian and Lebanese populations by two experienced dental surgeons twice within 1 month. Descriptive and comparative tests were used to analyze the patterns of ageneses and make comparisons between the two samples.

Results

23.4% of the studied sample had at least one third molar agenesis; females were more likely to have two or more third molar agenesis than males, but neither sex predisposition for single third-molar agenesis was recorded. Both the Italian and Lebanese subgroups seemed to have similar results. The maxillary right third molar was the most common third molar to be absent. Two or more ageneses were more common than one third molar agenesis.

Conclusion

Our Mediterranean population results fall within the range reported in the literature and corroborate with the global average prevalence.

Comparison of two established 2D staging techniques to their appliance in 3D cone beam computer-tomography for dental age estimation

For medicolegal purposes, orthodontic or orthognathic treatment various stomatological staging technique for age estimation with appliance of conventional radiographic images have been published. It remains uninvestigated if cone beam computer-tomography delivers comparable staging results to the conventional radiographic stages of third molar analysis. We conducted a retrospective cross-sectional study of 312 patients aged 13–21 years. Dental age estimation staging technique, introduced by Nolla and Demirjian, were applied on the left lower third molar imaged by conventional panoramic radiographs and cone beam computer-tomography. It was investigated if 2D and 3D imaging presented different staging results for dental age estimation. In 21% the Demirjian’s staging differed by a single stage between 2 and 3D images. The greatest congruence (87%) between 2 and 3D images was revealed for stage 7 (G). In contrary, stage 5 (E) presented the lowest level of congruence with 47.4%. The categorization of Nolla revealed divergences in staging for than two categorical variables in Nolla’s stages 3, 4, 5 and 6. In general, the analysis of the data displayed the divergence for Nolla’s stages 4–8. The staging results for 2D and 3D imaging in accordance to the rules of Nolla and Demirjian showed significant differences. Individuals of 18 years may present immature third molars, thus merely an immature third molar cannot reject legal majority. Nolla’s and Demirjian’s 2D and 3D imaging present significantly different staging results.

Radiographic pathologies associated with third molar teeth in Polish population: A retrospective study

Introduction: There is a plethora of pathologies that might be associated with the presence of third molar teeth (M3s). In the following study, the impact of M3s status on the occurrence of radiographic lesions of adjacent second molars (M2s) was evaluated. Materials/Methods: A total of 1,988 panoramic radiographs were included in the statistical analysis. M3s were categorized as non-impacted (N-M3s) or impacted (I-M3s). I-M3s were subsequently divided into partially or completely impacted. Radiographic lesions in the second molars area, such as caries, external root resorption (ERR), and alveolar bone loss (ABL) were assessed. For the purpose of statistical analysis, the level of significance was set at 0.05. Results: Among all evaluated panoramic radiographs, 1,621 (81.13%) showed at least one N-M3, 535 (26.78%) at least one partially I-M3, and 344 (17.2%) at least one completely I-M3. In the presence of M3s, the frequency of caries, ERR and ABL was determined at 17.98%, 0.68% and 23.96%, respectively, with the odds ratio (OR) for the occurrence of the above-mentioned pathologies at the level of 1.23, 6.97 and 1.31. Notably, the presence of N-M3s particularly increased the odds of caries, while I-M3s significantly increased the odds of ERR and ABR (ORs = 1.42; 26.0; 2.36, respectively). Conclusions: The presence of M3s, irrespective of their impacted or non-impacted status, increases the risk of pathologies in M2s. Therefore, prophylactic extraction of M3s or active surveillance of patients could be recommended.

Evaluation of third molar agenesis associated with hypodontia and oligodontia in turkish pediatric patients

Purpose

To evaluate the association between third molar (M3) agenesis and hypodontia and oligodontia in pediatric patients by using panoramic radiography.

Materials and methods

Panoramic radiographs of 1,471 patients (899 females; 572 males) and 5,884 teeth were retrospectively evaluated. The age and gender of the patients were recorded. Patients ages 9-15 years old were included in the study. The mean age was 12.76. The agenesis of M3 teeth and the relationship between M3 agenesis and hypodontia and oligodontia were recorded according to findings from the upper and lower jaw, in both the right and left locations, along with the number of M3 with agenesis. Data were analyzed using chi-square and McNemar tests (p<0.05).

Results

A total of 1,319 (89.7%) patients had all M3 teeth present in the mouth, while the other 152 (10.3%) had congenital agenesis in one or more teeth. The number of teeth in which M3 agenesis was seen, in order of the number of missing M3 teeth, the percentages were 2.6% for one, 2.4% for two, 1.0% for three and 4.3% for four missing teeth.Hypodontia was detected in 37 patients and oligodontia was detected in 3 patients.

Conclusion

The prevalence of M3 agenesis varies from one population to another. Two of the dental anomalies associated with M3 agenesis are hypodontia and oligodontia. In this study, M3 agenesis varied in terms of region and gender; hypodontia was also significantly higher in patients with missing mandibular M3.

A new model of classification of third molars development and its correlation with chronological age in a Brazilian subpopulation

The present study correlated the mineralization of third molars to chronological age using a modified classification based on Demirjian's stages in a Brazilian subpopulation and compared with the original classification. A total of 1082 patients with age ranging from 6 to 26 years were included in the sample, with at least one third molar on panoramic radiographs. The third molars were classified according to the original Demirjian classification (8 stages) and a new model based on the Demirjian method, where the original stages were grouped into four stages: AB-enamel mineralization; CD-crown dentin mineralization; EFG-root formation; and H-complete development. Statistical analyses were performed by Kruskal-Wallis/Dunn tests (α = 0.05) and the multinomial logistic regression model. Data were analyzed according to percentiles for the probability of an individual being over 18 years old. The mean ages of the stages in both classifications did not present a significant difference between superior and inferior arches (p < 0.05). The differences in mean ages between all the stages of mineralization were statistically significant (p < 0.001) only for the 4-stage classification. Males attained root formation and complete formation earlier than females (p < 0.05) in the 4-stage classification. The modified classification system showed dependence between chronological age and mineralization stages of third molars, simplifying the age estimation process. At stage H, females present a 95.7% chance of being over 18, while for males, this probability is 89.6%. This modified classification system simplifies the dental age estimation process based on third molars and can be used as a reference for future studies.

Analysis of permanent second molar development in children born with cleft lip and palate

OBJECTIVE

The study of dental development in individuals born with cleft lip and palate (CLP) serves to determine when orthodontic intervention should start. To evaluate the permanent second molar development in children born with cleft lip and palate according to Demirjian's and Nolla's methods.

METHODOLOGY

Out of a total of 513 digital panoramic radiographs, 113 pairs of children aged 3 to 16 years were selected. The exams were from children born with or without cleft lip and palate, of the same sex, with an age difference of up to 30 days. The images were analyzed by three examiners and reliability was checked through intra-examiner agreement by the Kappa test. The data were analyzed by Wilcoxon's and Mann-Whitney tests according to each dataset.

RESULTS

The findings indicated delayed development of the permanent second molars in children with CLP (P<0.001). The development of the right permanent second molar was delayed compared to the left molar in children with CLP. Moreover, mandibular teeth showed significantly earlier development than maxillary teeth in both the case and control groups. There was no significant difference in the development of permanent second molars between sexes.

CONCLUSION

Children with CLP presented delay in the development of permanent second molars.

Radiological Evaluation of Dental Age Assessment Based on the Development of Third Molars in Population of Bosnia and Herzegovina

OBJECTIVES

The development of third molars can be helpful in dental age estimation of adolescents and in early adult period. We tested the repeatability and accuracy of the three dental age radiographic methods (Olze, Demirjian and Solari and Abramovitch) and evaluated which method is more useful. We also aimed at testing to find the correlation of estimated dental and chronological age by these three methods.

MATERIAL AND METHODS

The orthopantomographs (OPGs) of 1007 individuals (8 - 25 years) were divided into two groups (cca 500 OPGs) - one group of OPGs has been presented with all four third molars, while another one was registered with third molar/s hypodontia. And all of OPGs were assessed, to verify the three methods (Olze, Demirjian and Solari and Abramovitch) for age estimation based on third molar development.

RESULTS

There was a high Spearman's correlation coefficient between stages of development of wisdom tooth and chronological age of subjects by all these three methods.

CONCLUSION

We may recommend using third molars for assessing the dental age by Olze, Demirjian and Solari and Abramovitch dental method as well, on Bosnian and Herzegovinian population.

Can canines alone be used for age estimation in Chinese individuals when applying the Kvaal method?

Due to the secondary dentin formation, the dental pulp undergoes changes in shape throughout life. Based on this phenomenon, the Kvaal method has been applied to various populations for age estimation, and its usefulness has been verified. When applying the Kvaal method to Chinese subjects, we observed a relatively strong correlation between mandibular canines and age. This study notes the correlation between canines and chronological age and is the first to identify which canine is most closely related to chronological age. In addition, a new, simpler formula is determined based on canines according to Kvaal's methodology. The radiographs of 360 individuals from northern China were selected, from which the widths and lengths of the pulp from four canines were measured according to the Kvaal method. Next, inter- and intra-observer reliabilities were analyzed in order to assess the repeatability of these measurements. The correlation between measurements and age was examined, and Chinese-specific age estimation formulae were derived. The results revealed that the ratios from the left maxillary canine exhibited the strongest correlation with age compared to the other canines, whereas the left mandibular canine showed the weakest correlation, which may contribute to the overall poor correlation of mandibular canines with age. What's more, the formula derived from the left maxillary canine in this study displayed the highest coefficients of determination, and the formula derived from all canines showed the lowest residuals. Both of these formulae performed better than the Chinese-specific formula derived from six different types of teeth in our previous study, which had formerly possessed the highest coefficients of determination and the lowest residuals. Thus, we concluded that canines do play an important role in age estimation in the Chinese population, and the correlation between maxillary canines and chronological age is stronger than that of mandibular canines, although no distinct trend as to which side is better correlated with age was established. Going forward, we recommend the analysis of additional samples from different geographical regions and populations to further verify the importance of canines in age estimation.

Prophylactic extraction of non-impacted third molars: is it necessary?

BACKGROUND

The decision of removing a non-impacted 3rd molar, unlike extraction of an impacted 3rd molar, is challenging for dentists as well as patients. This study investigates the pathologies affecting second molars situated adjacent to asymptomatic non-impacted 3rd molars.

METHODS

This retrospective study included digital radiographs of 749 patients taken between April to October 2015. Panoramic radiographs were evaluated for the presence of erupted asymptomatic non-impacted 3rd molars and pathologies on adjacent second molars. The patients were reviewed according to age and gender.

RESULTS

A total of 2342 asymptomatic 3rd molars were assessed in the study based on the inclusion and exclusion criteria, and 2112 of them were found to be non-impacted. The second molars adjacent to non-impacted 3rd molars were shown to be significantly associated with distal caries (25.2%), mesial bone loss (10.5%) and total bone loss (37.2%), i.e., mesial as well as distal bone loss.

CONCLUSIONS

Pathologies of the 3rd molars and teeth adjacent to 3rd molars can occur as a result of multiple factors. Caries and periodontal disease may also occur due to the inaccessibility to maintain oral hygiene. With a regular follow-up schedule, reinforced by the dentist and good oral hygiene, several pathologies that are significantly associated with non-impacted 3rd molars can be prevented and may not require prophylactic extraction.

Longer analgesic effect with naproxen sodium than ibuprofen in post-surgical dental pain: a randomized, double-blind, placebo-controlled, single-dose trial

Background: Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line medications in mild-to-moderate acute pain. However, comparative data regarding the duration of analgesia for commonly-used NSAIDs at non-prescription doses is lacking. This study evaluated the time to rescue medication following a single dose of naproxen sodium (NAPSO) vs ibuprofen (IBU) and placebo in subjects with moderate-to-severe post-surgical dental pain.Methods: This single-center, randomized, double-blind, parallel group, placebo-controlled study included healthy subjects with moderate-to-severe baseline pain (Categorical Pain Intensity Scale) who also rated their pain ≥ 5 on a 0-10 pain intensity Numerical Rating Scale following extraction of two impacted mandibular third molars. A single oral dose of NAPSO (440 mg), IBU (400 mg), or placebo was administered. The primary efficacy endpoint was the time to first rescue medication, while secondary endpoints included the sum of pain intensity difference (SPID) and total pain relief (TOTPAR) over 24 h. ClinicalTrials.gov trial registration number: NCT03404206 (EudraCT 2017-005049-67).Results: In the per protocol population (n = 385; mean age = 19 years), the time to rescue medication was significantly (p < .001) longer with NAPSO than IBU and placebo. After treatment, the greatest separation of NAPSO from IBU occurred at 9-14 h and from placebo at 1-6 h. Fewer NAPSO subjects required rescue medication (58/166, 34.9%) compared with IBU (137/165, 83.0%) and placebo (44/54, 81.5%). SPID 0-24 h and TOTPAR 0-24 h were both greater with NAPSO than IBU or placebo.Conclusions: The duration of pain relief after a single dose of NAPSO was significantly longer than after IBU, and significantly fewer NAPSO-treated subjects required rescue medication over a 24-h period.

Effect of extraction or nonextraction orthodontic treatment modality on favorability of eruption of impacted third molars

Objective

The objective of the study is to determine if extraction of permanent teeth, for orthodontic purpose, causes a change in third molar angulation and also to determine if extraction of permanent teeth causes an increase in eruption space available for third molars.

Methods

This systematic review includes retrospective cohort studies which evaluated the change in third molar angulation or eruption space available for third molars among orthodontic patients treated by a fixed appliance with either extraction or nonextraction protocol. Search engines used were MEDLINE, IndMED, Web of Science, Cochrane, EMBASE, and Google Scholar from the year 1975 to 2015. Separate data collection forms were used to extract data from the studies. The Cochrane Risk of Bias Assessment Tool was used to assess the studies included in the systematic review.

Results

Fifteen studies included in the systematic review proved that third molar angulation and eruption space improved in patients treated with extraction treatment modality. However, two studies concluded that change in third molar angulation and eruption space occurred irrespective of the type of treatment involved.

Conclusion

The angulation and eruption space of third molar improved following extraction of premolar or molar. Nonextraction treatment modality did not cause any adverse effects.

Three-dimensional image analysis of developing mandibular third molars apices for age estimation: A study using CBCT data enhanced with Mimics & 3-Matics software

Three-dimensional imaging has improved the method of analysis in many forensic science investigations. The study aimed to derive regression equation for age estimation by investigating the relationship between chronological age and surface area of the developing mandibular 3rd molars apices. Furthermore, other predictor variables: ethnicity (Malay and Chinese), gender and status of the root development completion (open/closed apices) were also investigated in terms of fit to the age estimation model. One hundred and twenty eight training and 55 validation samples of intact mandibular 3rd molars were selected from 183 CBCT scans. The samples comprised of 93 Malays and 90 Chinese, ranging in age from 13 to 24 years. Three-dimensional image modeling and surface area analysis of the developing mandibular 3rd molars apices were performed using Mimics and 3-Matics software. Multiple linear regression analysis was used to derive age estimation model using chronological age as a dependent variable and surface area of the apices, ethnicity, gender and status of the root development completion (open/closed apices) as predictor variables. A strong inverse correlation (r = 0.95, SD = 1.144) was observed between chronological age and all the predictor variables. The results showed that 89.6% of the variation in age can be explained by the predictor variables. Mean absolute error (MAE) value of 0.8223 was observed when the derived regression equation was tested on the independent validation sample. In conclusion, three-dimensional surface area analysis of the developing mandibular 3rd molars apices can be used as a reliable method for age estimation.

Genetic and environmental influences on third molar root mineralization

OBJECTIVE

To assess the genetic and environmental influences on the variability of human third molar (M3) root mineralization stages via a twin study.

DESIGN

The study sample consisted of 162 same-sex twins (66 dizygotic and 96 monozygotic, mean age: 17.9 years) with normal growth and development. Panoramic radiographs were evaluated to assess root mineralization stages of the upper and lower third molars, using the method of Demirijian et al. (1973). Zygosity was established using 15 specific DNA markers.

RESULTS

Females developed their third molar roots earlier in life than males. Monozygotic twins (MZ) demonstrated higher intra-pair correlations for M3 root development stages than did DZ twins. An ACE model with additive genes, as well as common and specific environmental factors, provided the best explanation of variation in M3 root development. The mineralization of M3 roots showed highly additive genetic determination, varying from 60 to 63%, whereas a common environment contributed from 25 to 27%, and a specific environment only accounted 14% of the total variation, at most.

CONCLUSIONS

A considerable proportion of the total variability of the third molar root mineralization rate can be attributed to additive genetic effects, while common and specific environmental effects have a smaller, yet significant, impact.

A systematic review and meta-analysis of the fully formed wisdom tooth as a radiological marker of adulthood

Assessment of third molar development on dental radiograms is one of the most commonly used methods of forensic age estimation. Despite widespread use and numerous studies, there is a paucity of aggregated data on how well a fully mature third molar identifies adulthood (> 18 years), the most important threshold in a medicolegal context. Therefore, a systematic review and meta-analysis was conducted. A total of 1229 studies were screened, and 82 studies were assessed for inclusion. Twenty-four studies, with a pooled cohort of 19,690 individuals, presented true positive (TP), true negative (TN), false positive (FP), and false negative (FN) outcomes, enabling meta-analysis. The outcomes were based on using the third molar in the fully mature stage as a diagnostic test to indicate age 18 years or above. The false positive rate (fall-out/1-specificity) was 3.1% (95% CI 2.1-4.6%), and the true positive rate (recall/sensitivity) was 51% (95% CI 44-58%). Diagnostic accuracy was 71%. These findings, while reassuring in terms of the low false positive rate, highlight the need for complementary age estimation methods to avoid a significant number of false negatives.

Effect of demineralization time on the mineral composition and mechanical properties of remineralized dentin

The aim of this study was to determine whether recovery of mineral levels restored the mechanical properties of dentin subjected to different durations of demineralization. Dentin at the floor of class 1 cavities (n = 12) was demineralized for 1, 2, and 3 weeks. Half the demineralized cavity floor was coated (control side), and a Fuji IX restoration was placed. The remaining half was therefore in contact with the Fuji IX restoration (test side). Simulated dentin tubular fluid was then supplied to each pulp chamber for 6 weeks. After remineralization, the teeth were detached from the system and sectioned. Concentrations of calcium, phosphorus, fluorine, and strontium and mechanical properties (hardness and Young's modulus) of the test and control sides were determined by electron probe microanalysis and nano-indentation, respectively. For remineralized dentin demineralized for 1 week, the substantial uptake of mineral elements restored hardness and Young's modulus at depths of 50 to 200 μm from the lesion front. For longer periods of demineralization (2 and 3 weeks), structural damage to the demineralized dentin was severe and impeded recovery of mechanical properties, despite mineral uptake.

Third molar mineralization in relation to chronologic age estimation of the Han in central southern China

The purpose of this study is to provide a forensic reference data about estimating chronologic age by evaluating the third molar mineralization of Han in central southern China. The mineralization degree of third molars was assessed by Demirjian's classification with modification for 2519 digital orthopantomograms (1190 males, 1329 females; age 8-23 years). The mean ages of the initial mineralization and the crown completion of third molars were around 9.66 and 13.88 years old in males and 9.52 and 14.09 years old in females. The minimum ages of apical closure were around 16 years in both sexes. Twenty-eight at stage C and stage G and 38 and 48 at stage F occurred earlier in males than in females. There was no significant difference between maxillary and mandibular teeth in males and females except that stage C in males. Two formulas were devised to estimate age based on mineralization stages and sexes. In Hunan Province, the person will probably be over age 14, when a third molar reaches the stage G. The results of the study could provide reference for age estimation in forensic cases and clinical dentistry.

Third molar agenesis as a potential marker for craniofacial deformities

The identification of clinical patterns of tooth agenesis in individuals born with craniofacial deformities may be a useful tool for risk determination of these defects. We hypothesize that specific craniofacial deformities are associated with third molar agenesis.

OBJECTIVE

The aim of this study was to identify if third molar agenesis could have a relation with other craniofacial structure alterations, such as cleft lip and palate, skeletal malocclusion, or specific growth patterns in humans.

DESIGN

Data were obtained from 550 individuals ascertained as part of studies aiming to identify genetic contributions to oral clefts. 831 dental records of patients aged over eight years seeking orthodontic treatment were also included. SN-GoGn angle were used to classify the growth pattern (hypo-divergent, normal and hyper-divergent), and the ANB angle was used to verify the skeletal malocclusion pattern (Class I, II and III). Panoramic radiographs were used to determine third molar agenesis.

RESULTS

A high frequency of third molar agenesis among individuals born with cleft lip with or without cleft palate (55%), as well as among their relatives (93.5%) was found. Third molar agenesis was not associated to skeletal malocclusion or growth pattern.

CONCLUSION

It appears that third molar agenesis is associated with the disturbances that lead to cleft lip and palate.

The evidential value of developmental age imaging for assessing age of majority

Aim: To consider the evidential value of developmental age images for identifying age of majority.

Methods: The published literature on hand–wrist X-rays, MRI scans of the distal radius and orthopantomograms of the lower left third molar is considered in terms of the mean age of attainment of the adult appearance and the diagnostic test performance of the adult appearance to predict adult status, either administratively (under-17 football) or forensically.

Results: The mean age of attainment of a mature hand-wrist X-ray is under 18 years and most individuals are mature before age 18. For the MRI wrist scan and the third molar the age of attainment is over 19 years and the adult appearance is an indicator of adulthood, while the immature appearance is uninformative about likely age. So MRI and third molars have high specificity, but low sensitivity.

Conclusions: Bone age assessed by hand–wrist X-ray is uninformative and should not be used. The adult appearance of MRI wrist scans and third molars provide evidence of being over-age, although there remains a small risk of minors being misclassified as adult. The immature appearance is uninformative about likely age and, overall, more than one third of assessments are wrong.

Evaluation of third molar development in the estimation of chronological age

The purpose of this study was to evaluate the correlation between chronological age and the degree of third molar mineralization by Demirjian's developmental stages (Demirjian et al., 1973) using panoramic radiography. From a total of 11.396 digital panoramic radiographs of patients from three oral radiology private clinics from the northeast region of Brazil, obtained from January to June 2009, 2097 radiographic images from patients aged between 6 and 22 years were selected. The images were analyzed individually by two obsevers using a 21-inch computer screen and Windows Picture and Fax Viewer. Reliability was achieved by intra- and interobserver evaluation, using the Kappa test. Chronological age, calcification stage, gender and third molar were interrelated using a multiple linear regression model, considering age as a response variable. There was reliability with Demirjian et al.'s developmental stage assesment, displaying a significant relationship between mineralization stages and patients' age (P<0.05). There was no significant difference between the average age and the calcification stage taking gender and localization of the third molar into consideration. It is possible to estimate chronological age based on Demirjian's stage of a third molar, regardless of gender and location.