Third Molar Agenesis Research Articles

Unilateral delayed eruption of a mandibular permanent canine and the maxillary first and second molars, and agenesis of the maxillary third molar

Delayed tooth eruption can affect the accuracy of orthodontic diagnosis and treatment planning and could delay overall treatment. A girl, aged 7 years 4 months, who had unilateral delayed eruption of several teeth was successfully treated. The evaluation of delayed tooth eruption should be considered by the orthodontist because the role of these teeth can affect the overall treatment of malocclusion. In patients with delayed tooth eruption, careful and accurate diagnosis and treatment planning will allow the orthodontist to start treatment at the proper stage and might reduce the overall orthodontic treatment time.

Prevalence of Mandibular Third Molar Impaction and Agenesis: A Radiographic South Indian Study

Aims and objective: To evaluate the prevalence of (i) impaction of mandibular third molar, (ii) agenesis of mandibular third molar and (iii) angulation of impaction radiographically. Materials and methods: The sample size consists of 1,005 patients above 18 years. The orthopantomograph of the patients are interpreted for eruption/pattern of impaction/agenesis of mandibular third molar. Conclusion: Bilateral impaction of mandibular third molar is common than unilateral impaction. Agenesis of mandibular third molar is seen in 12.2 to 12.5% of patients. Mesioangular is the commonest pattern of impaction. No sex predisposition is in prevalence of impaction. Agenesis is seen more commonly in females than males.

Agenesis of Third Molars in Orthodontic Patients attending Dhulikhel Hospital

Aims and objective: The aim of this descriptive study was to determine the prevalence of agenesis or congenitally missing third molars in orthodontic patients attending Dhulikhel Hospital.
 Materials & Methods: A retrospective study of a total of 294 patients, of both genders ranging from 12 to 34 years of age who were orthodontically treated between August, 2010 to May 2012, were reviewed from the files of the Department of Orthodontics, Dhulikhel Hospital, Kathmandu University Hospital. The records included panoramic radiographs and study models of all patients with intra oral photographs at the beginning of treatment.
 Results: It shows that agenesis of one to four third molars was present in male group in 63 cases out of 94, i.e, 67.02% and in the female group in 85 cases out of 200, i.e. in 42.5%. In the group of male and female together, we found the agenesis of one to four third molars in 148 cases, which is 50.34 %.
 Conclusions: Data concerning the incidence of third molars agenesis belong to the essential characteristics of the dentition's status of the given population. Dental developmental anomalies can indicate the degree of genetic load of individuals and relatives. By analyzing the global term "agenesis of one to four third molars" it is possible to receive data, which are quite significant for the orthodontic treatment plan.

Prevalence of eruption status of third molars in Libyan students.

The aim of the present study is to determine the number of third molars per person, angulation, level, amount of space for eruption of third molar between ramus of mandible and second molar and the eruption status of third molar in a group of Libyan students, with different impaction patterns and agenesis of third molars. In this descriptive retrospective study, a total of 200 students (100 male and 100 female students of bachelor of dental surgery, Faculty of Dentistry, Garyounis University, Benghazi, Libya) were enrolled. Students who had complete complement of teeth within the age group 17-26 years were selected for this study, while those cases who had history of extraction of any of the teeth or who refused to give consent were excluded. Before starting the study, ethical concern from the ethical committee, IRB and informed consent from each student who underwent radiography were obtained. The results showed that 5% of third molars were congenitally missing. Approximately 93.5% of the subjects had all four third molars, 1% had two third molars and 0.5% had one third molars with 2.5% having agenesis of all third molars. Third molar agenesis showed predilection for maxilla with higher proportion in females (3%) than males (2.1%). Angular position was maximum with vertical position (5.83%), with least being horizontal impactions. Level of occlusal plane of third molar similar to that of adjacent tooth was seen in 44.74%, below the occlusal plane in 24.76%, totally impacted noted in 30%. The present study showed that 33% of the teeth were fully erupted and 66% were in various stages of eruption and 5% were congenitally missing in these students.

Idiopathic nonsyndromic tooth agenesis: A report of rare three

Tooth agenesis is a common developmental anomaly that appears in 2.2-10% of the general population (excluding agenesis of third molars). Congenital tooth agenesis can be either hypodontia (agenesis of fewer than six teeth excluding third molars) or oligodontia (agenesis of more than six teeth excluding third molars). Oligodontia can occur either as an isolated condition (nonsyndromic oligodontia) or it can be associated with cleft lip or palate and other genetic syndromes (syndromic oligodontia). The exact aetiology of oligodontia is unknown. The management includes various procedures such as restorative, surgical, and orthodontic to improve the aesthetics and function. This article reports rare three cases of congenitally missing permanent teeth with over-retained deciduous dentition and review the literature citing its etiology, clinical implications, and management.Clinical relevance to interdisciplinary dentistryThe timing of diagnosis is not only important for choosing an appropriate treatment plan, but also for obtaining successful treatment results.The missing teeth, abnormal occlusion, or altered facial appearance may cause psychological distress in some or all patients.Treatment includes multidisciplinary team approach of pedodontists, orthodontists, oral and maxillofacial surgeons, and prosthodontists to restore aesthetics, functional, and psychological reasons depending on the severity of the condition and patient's perceived need for careThe treatment not only improves speech and masticatory function, but also has psychological implications that may greatly help in regaining self-confidence.

Radiographic study of mandibular angular cortical thickness in relation to the presence and eruption status of mandibular third molar

Background: Mandible is one of the largest and strongest facial bones but there are some areas which are physically weak and fractured easily, i.e., angle and condyle. Recent studies demonstrated the correlation of the risk of mandibular angle fractures to the presence of the mandibular third molars. The aim of the present study was to evaluate the mandibular angular cortical thickness in relation to the presence and eruption status of mandibular third molar to verify if the mandibular third molar represent a risk factor for angle fracture or not. Materials and methods: The angular cortical thickness was measured using tracing elements and panoramic radiograph of 160 Iraqi subjects aged from (20-28) years, they were divided equally into four groups according to the status of mandibular third molar which were: Subjects with agenesis of mandibular third molar, subjects with completely erupted mandibular third molar, subjects with complete bony impacted mandibular third molar and subjects with extracted mandibular third molar. Results: Subjects with agenesis registered the greatest value in the mean angular cortical thickness followed by subjects with extracted, completely erupted and complete bony impacted mandibular third molar respectively. Extraction of mandibular third molar improved the angular cortical thickness and this effect had a strong positive linear correlation with the extraction duration. Conclusion: The measurement of the angular cortical thickness was greatly affected by the presence and eruption status of mandibular third molar, such measurements registered its highest values in subjects with third molar agenesis and its lowest values in subjects with complete bony impacted third molar.

Patterns of third-molar agenesis and associated dental anomalies in an orthodontic population

The aim of this study was to investigate the frequency of dental anomalies in orthodontic patients with different patterns of third-molar agenesis, comparing them with patients without third-molar agenesis. A sample of 374 patients with agenesis of at least 1 third molar was divided into 4 groups according to the third-molar agenesis pattern, and a control group of 98 patients without third-molar agenesis was randomly selected from the patient archives. Panoramic radiographs and cast models were used to determine the associated dental anomalies, such as hypodontia, hyperdontia, impaction, dilaceration, microdontia, ectopic eruption, transposition, and transmigration. The Pearson chi-square and Fisher exact tests were used to determine the differences in the distribution of the associated dental anomalies among the groups. The prevalence of agenesis of other teeth (11.2%, n = 42) was significantly greater in our study sample (groups 1-4) than in the control group (group 5) (4.1%, n = 4; P <0.05). When we compared the groups according to the various third-molar agenesis patterns, we found that agenesis of other teeth was more common in patients with agenesis of 3 and 4 third molars. In addition, the patients with agenesis of 4 third molars exhibited maxillary lateral-incisor microdontia more frequently. Another important finding was a higher prevalence of total dental anomalies in patients with agenesis of 3 and 4 third molars compared with the control group. Permanent tooth agenesis, microdontia of maxillary lateral incisors, and total dental anomalies are more frequently associated with agenesis of 4 third molars than with the presence of third molars.

Patterns of third-molar agenesis in an orthodontic patient population with different skeletal malocclusions

To examine the relationship between third-molar agenesis and different skeletal malocclusion patterns. Pretreatment records of 1046 orthodontic patients (aged 13-17 years; mean age, 14.07 ± 1.27) were used. Third-molar agenesis was calculated with respect to genders, number of missing teeth, jaws, and skeletal malocclusion patterns. The Pearson chi-square test was performed to determine potential differences. Among the 1046 subjects, 237 subjects were diagnosed with third-molar agenesis (22.7%) with no statistical gender difference (P > .05). It was more common in the maxilla than in the mandible or in both jaws (P < .01). The prevalence of patients with a third-molar agenesis was the most commonly found type (P < .001). The prevalence of third-molar agenesis in those with a Class III malocclusion was significantly higher than in those with Class I or Class II (P < .05). However, there was similar prevalence among the hyper-divergent (24.5%), normal (23.8%), and hypo-divergent (19.2%) groups (P > .05). These results suggest that agenesis of the third molar does not depend on vertical patterns of the skeletal malocclusions, but does depend on sagittal skeletal malocclusions in this orthodontic patient population.

Incidence of the Anatomic Positions and Agenesis of Third Molars in Students from São Luís, MA, Brazil

Objetivo: Investigar os aspectos clinicos e radiograficos dos terceiros molares com relacao a incidencia das posicoes anatomicas e agenesia em estudantes de uma escola publica de Sao Luis, Maranhao. Metodo: Trata-se de um estudo transversal descritivo das caracteristicas clinicas e radiograficas dos terceiros molares numa populacao de estudantes de 18 a 21 anos de ambos os generos. Avaliou-se 155 pacientes por meio de exame clinico e radiografico (radiografia panorâmica dos maxilares) no periodo de maio a novembro de 2006. Dos 155 estudantes, obtivemos 531 dentes presentes e 89 ausentes. Dos presentes, somente 462 foram avaliados segundo as posicoes de Winter e Pell e Gregory, visto que apresentavam rizogenese completa. Registraram-se ainda a ausencia congenita destes dentes. Todos os dados foram registrados em fichas apropriadas, tabulados no EPI-INFO 2000 e submetidos ao teste Qui-Quadrado para verificar a existencia de associacoes entre as variaveis de estudo, com nivel de significância de 5%. Resultados: Os resultados mostraram diferencas significantes para as posicoes mesial (p=0.0001), distal (p=0.0278) e horizontal (p=0.0179) em relacao aos diferentes terceiros molares. Ja para a posicao vertical nao houve diferencas. (p=0.1354), entretanto foi mais frequente na amostra. Com relacao a classificacao de Pell e Gregory nao foram observadas diferencas significantes (p>0.05). A agenesia foi consideravelmente frequente nesta populacao com 14,4%. Conclusao: As posicoes mais frequentes segundo Winter foram a vertical seguida pela mesial, distal e horizontal; e segundo Pell e Gregory foram Classe I, II e III e Posicoes A, B e C . A agenesia esteve frequente na amostra.

Maxillary first molar agenesis and other dental anomalies

To explore the association of maxillary first molar agenesis with other dental anomalies in Japanese orthodontic patients. A total of 32 subjects with one or two congenitally missing maxillary first molars (group M) were selected and divided into group 1M (12 subjects with one maxillary first molar missing) and group 2M (20 subjects with two maxillary first molars missing). As controls, 32 sex-matched subjects without agenesis of maxillary first molars were collected (group C). Panoramic and periapical radiographs, cephalograms, study models, intraoral photographs, and anamnestic data were used to identify anomalies of permanent teeth. Chi-square, Fisher's exact, Kruskal-Wallis, and Steel-Dwass tests were used to make statistical comparisons. The prevalence rates of tooth agenesis other than the maxillary first molars and advanced tooth agenesis, with third molars excluded, were significantly higher in group 2M than in group C. The absence of second premolars was most common. The prevalence rate of third molar agenesis was significantly higher in groups 1M and 2M than in group C. The occurrence of symmetrical agenesis of the mandibular third molars was particularly notable in group 2M as compared to group 1M, in which maxillary third molar agenesis was predominant. There was no significant association between maxillary first molar agenesis and other dental anomalies, except for agenesis of teeth other than maxillary first molars. Agenesis of maxillary first molars is associated with a higher prevalence of other permanent tooth agenesis and advanced tooth agenesis.

Editor's Comment and Q&A: Agenesis of maxillary lateral incisors and associated dental anomalies

<h3>Introduction</h3> The objectives of this study were to evaluate the prevalence of dental anomalies in patients with agenesis of maxillary lateral incisors and to compare the findings with the prevalence of these anomalies in the general population. <h3>Methods</h3> A sample of 126 patients, aged 7 to 35 years, with agenesis of at least 1 maxillary lateral incisor was selected. Panoramic and periapical radiographs and dental casts were used to analyze other associated dental anomalies, including agenesis of other permanent teeth, ectopia of unerupted permanent teeth, microdontia of maxillary lateral incisors, and supernumerary teeth. The occurrence of these anomalies was compared with prevalence data previously reported for the general population. Statistical testing was performed with the chi-square test (<i>P</i> <0.05) and the odds ratio. <h3>Results</h3> Patients with maxillary lateral incisor agenesis had a significantly increased prevalence rate of permanent tooth agenesis (18.2%), excluding the third molars. The occurrence of third-molar agenesis in a subgroup aged 14 years or older (n = 76) was 35.5%. The frequencies of maxillary second premolar agenesis (10.3%), mandibular second premolar agenesis (7.9%), microdontia of maxillary lateral incisors (38.8%), and distoangulation of mandibular second premolars (3.9%) were significantly increased in our sample compared with the general population. In a subgroup of patients aged 10 years or older (n = 115), the prevalence of palatally displaced canines was elevated (5.2%). The prevalences of mesioangulation of mandibular second molars and supernumerary teeth were not higher in the sample. <h3>Conclusions</h3> Permanent tooth agenesis, maxillary lateral incisor microdontia, palatally displaced canines, and distoangulation of mandibular second premolars are frequently associated with maxillary lateral incisor agenesis, providing additional evidence of a genetic interrelationship in the causes of these dental anomalies.

Agenesis of maxillary lateral incisors and associated dental anomalies

The objectives of this study were to evaluate the prevalence of dental anomalies in patients with agenesis of maxillary lateral incisors and to compare the findings with the prevalence of these anomalies in the general population. A sample of 126 patients, aged 7 to 35 years, with agenesis of at least 1 maxillary lateral incisor was selected. Panoramic and periapical radiographs and dental casts were used to analyze other associated dental anomalies, including agenesis of other permanent teeth, ectopia of unerupted permanent teeth, microdontia of maxillary lateral incisors, and supernumerary teeth. The occurrence of these anomalies was compared with prevalence data previously reported for the general population. Statistical testing was performed with the chi-square test (P <0.05) and the odds ratio. Patients with maxillary lateral incisor agenesis had a significantly increased prevalence rate of permanent tooth agenesis (18.2%), excluding the third molars. The occurrence of third-molar agenesis in a subgroup aged 14 years or older (n = 76) was 35.5%. The frequencies of maxillary second premolar agenesis (10.3%), mandibular second premolar agenesis (7.9%), microdontia of maxillary lateral incisors (38.8%), and distoangulation of mandibular second premolars (3.9%) were significantly increased in our sample compared with the general population. In a subgroup of patients aged 10 years or older (n = 115), the prevalence of palatally displaced canines was elevated (5.2%). The prevalences of mesioangulation of mandibular second molars and supernumerary teeth were not higher in the sample. Permanent tooth agenesis, maxillary lateral incisor microdontia, palatally displaced canines, and distoangulation of mandibular second premolars are frequently associated with maxillary lateral incisor agenesis, providing additional evidence of a genetic interrelationship in the causes of these dental anomalies.

Frequency of Agenesis, Impaction, Angulation, and Related Pathologic Changes of Third Molar Teeth in Orthodontic Patients

The objectives of the present study were to investigate the frequency of impaction, agenesis, angular position, and related pathologic changes of third molar teeth in a group of orthodontic patients. Our sample included the panoramic radiographs of 351 orthodontic patients aged 20 to 26 years (mean 22.8). The descriptive characteristics of agenesis, impaction, angular position, and pathologic changes of third molars were recorded. The chi(2) test was used for analysis. The proportion of third molar agenesis was 17.3% with no statistically significant gender differences (18.4% for women and 15.8% for men). The frequency of impacted third molars (ITMs) was 35.9% (24.2% in men and 45.0% in women; P < .05). The frequency of maxillary ITMs was 43.2% (192 of 444 teeth), and the frequency of mandibular ITMs was 56.8% (252 of 444 teeth). The position observed most often was mesioangular inclination, with a frequency of 50.0%. Only 10.4% of the ITM teeth were affected by any pathologic changes, and most of these changes were associated with the horizontal position. The present results showed that agenesis accounted for 17.3% and impaction for 35.9% of the pathologic features in this group of Turkish orthodontic patients aged 20 to 26 years of age. Mesioangular inclination was seen in 50.0%, and a small proportion (10.4%) had pathologic changes of the ITMs.

Third-Molar Agenesis among Patients from the East Anatolian Region of Turkey

The aim of this study was to determine the frequency and distribution of third-molar agenesis in orthodontic patients from the East Anatolian Region of Turkey. Our data were obtained from the panoramic radiographs of the 2,579 patients 12 to 16 years of age in the Department of Orthodontics at the Atatürk University in Erzurum, Turkey. Subjects with congenital deformities, such as a cleft palate, were excluded from the study. Statistical analysis was performed using SPSS software and a chi-squared test. Of the 2,579 subjects, 1,964 (76.2 percent) had all four third-molar teeth, 238 (9.2 percent) had three, 214 (8.3 percent) had two, 66 (2.6 percent) had one third molar, and 97 (3.8 percent) had agenesis of all third-molar teeth. There was no significant difference in agenesis of third-molar teeth between the right and left sides and no gender predilection was noted. However, significantly more third-molar teeth were found to be missing from the maxilla compared to the mandible, with a ratio of approximately 1.5:1. According to our results, the absence of one third molar is the most frequently detected pattern in the East Anatolian population. Additionally, the absence of third molars is more frequent in the maxilla than the mandible. To date no information about third-molar agenesis in the East Anatolian population from Turkey is documented. This is believed to be the first known study on this subject in this population.

Hypohyperdontia: Agenesis of three third molars and mandibular centrals associated with midline supernumerary tooth in mandible

Agenesis of teeth in a patient who also presents with a supernumerary tooth is one of the rare numerical anomalies in human dentition. Agenesis of third molars was shown to be associated with other missing permanent teeth. A review of literature on hypodontia including third molar agenesis, hyperdontia and a concomitant presence of these two conditions which is termed as hypohyperdontia is presented along with a case showing agenesis of three third molars, both mandibular central incisors and a midline supernumerary tooth.

Developmental disturbances associated with agenesis of the permanent maxillary lateral incisor

The aim of this study was to characterise the intra and extra-oral phenotype associated with agenesis of the permanent maxillary lateral incisor. We compared three groups: (1) subjects with agenesis of one or both permanent maxillary lateral incisors (n=80); (2) first and second degree relatives of group 1 with no agenesis of the permanent maxillary lateral incisor and (3) subjects with no agenesis of the maxillary lateral incisor or family history of it (n=49). For each of the 201 subjects detailed clinical information was reviewed and panoramic radiographs were analysed. Considering only the sample with unilateral agenesis, microdontia of the contralateral permanent maxillary lateral incisor was significantly more frequent in group 1 (82.4%) than in group 2 (25%) and the control group (2%). This supports the theory that microdontia is a variable expression of the same developmental disturbance that causes tooth agenesis. The absence of third molars occurred more often in group 1 (36.2%) than in groups 2 and 3 (18.6% and 18.9% respectively), confirming that agenesis of third molars was markedly associated with the agenesis of the permanent maxillary lateral incisor. Agenesis of teeth other than third molars was not significantly different among subjects with agenesis of the permanent maxillary lateral incisor and their relatives. The frequencies of supernumerary teeth, permanent maxillary canine impaction, general health condition and minor anomalies were not significantly different between the three groups.

The Relationship Between Third Molar Agenesis And Reduction In Tooth Number

The Relationship Between Third Molar Agenesis And Reduction In Tooth Number

Third Molar Agenesis and Craniofacial Morphology

To test the null hypothesis that agenesis of wisdom teeth is not related with any particular craniofacial morphology. Ninety-seven patients (aged 13-19 years) were selected and divided into three groups: (1) bilateral agenesis of maxillary third molars, (2) bilateral agenesis of mandibular third molars, and (3) control group without agenesis. Presence or absence of third molars was determined using ortopantomographs. Cephalometric analysis was carried out from lateral teleradiographs, which included linear, angular, and proportional measurements. When data obtained were distributed normally it was analyzed by means of single-factor variance analysis and the Scheffé test (P < .05). When data did not show normality, the Kruskal-Wallis test (P < .05) and the Mann-Whitney test were applied using Bonferroni correction (P < .017). Multivariance discrimination analysis was also carried out. Values obtained for the mandibular plain of Groups 1 and 2 were significantly lower than those of the Control Group (P =.00 and P =.00, respectively). For Group 2 lower face height was significantly less than for the control group (P =.01), whilst the mandibular arch and the articular angle were significantly greater than in the Control Group (P =.000 and P = .02, respectively). Multivariance discrimination analysis obtained a correct classification in 58.8% of cases. The hypothesis is rejected. Agenesis of the maxillary third molars was related to a reduced mandibular plane angle. Patients with agenesis of the mandibular third molars showed a diminished lower third and a mandibular morphology characteristic of the brachyfacial pattern.

Morphodigital study of bone quality in the mandibular angle in patients with third molar impacted

The aim of this study was to analyze if the presence of impacted third molars, and their positions in the mandibular angle, can change the bone quality in this area, considering the measure of the cortical thickness in this region as representative or not for mandible fracture risk. Software was used to analyze 50 digital images from panoramic radiographs of patients who had one or two impacted third molars in the mandible, and 30 digital images of patients with agenesis of the mandibular third molar. The thickness of the cortical region of the mandible was measured; it was possible to draw a parallel line to the posterior portion of the mandible and a parallel line to the body of this bone on each side of the image. At the intersection of these lines near the distal portion of the second molar, another line was set up to serve as reference in the cortical thickness measurement. It could be concluded that the cortical thickness of the mandibular angle in male patients without impacted third molars was greater than the thickness in patients with these teeth, and no difference in thickness was found for the female group.

Radiographic Evaluation of the Status of Third Molars in the Asian-Indian Students

The purpose of this study is to assess the prevalence and agenesis of third molars, their impaction status, and the time and sequence of their eruption in the students of Asian-Indian population. One hundred students with ages ranging from 17.5 to 20.0 years were randomly selected. This age group was selected because this is the age at which third molars normally begin to erupt. Students who had undergone any tooth extraction or orthodontic treatment previously were not included in the study. The incidence of congenital missing third molars was 11.5%, with a higher incidence in females. Of the third molars present, 31% were in mesioangular position, 42% were in the vertical position, 27% were in the distoangular position, and none were in the horizontal position. Of the 354 teeth examined, 24% of teeth were found to be erupted and 76% were in various stages of eruption. The level of eruption of third molars was 27% at A; 39%, B; and 34%, C. The present study showed that at the baseline (mean age, 19.3 years), 24% of third molars were erupted, 76% were in various stages of eruption, and 11.5% were congenitally missing in the Asian-Indian student population.