Prevalence Of Third Molar Agenesis Research Articles

Third molar agenesis in individuals with supernumerary teeth.

To explore the association between third molar agenesis and supernumerary tooth formation in a white-European population. A record review in various orthodontic clinics identified 380 eligible white-European individuals, half of whom had non-syndromic permanent supernumerary teeth (122 males and 68 females, totalling 244 supernumerary teeth; median age: 13.1, iqr: 1.5 years), and the other half were age- and sex-matched controls with full dentition, excluding the third molars. Tooth sequences were identified in panoramic radiographs. In the supernumerary group, approximately 80% of the individuals had a single supernumerary tooth, followed by those having two additional teeth. In both groups, there was no sexual dimorphism in third molar agenesis severity. The prevalence of third molar agenesis in the supernumerary group was similar to that of the control group (28/190 = 14.7% in both groups; p = 1.0). In total, 53 third molars were missing in the supernumerary group (n = 190) compared to 67 in the control group (n = 190; p = .862). The ratio of bilateral to unilateral third molar agenesis was significantly lower in the supernumerary group than in the control group (1.0 vs. 3.7, respectively; p = .026). The presence of supernumerary teeth did not significantly alter the likelihood of third molar agenesis or its severity. Bilateral third molar agenesis was considerably less prevalent in individuals with supernumerary teeth compared to controls. The present novel findings have important clinical and developmental implications.

Radiographic Assessment of Agenesis of the Third Molars: A Cross-sectional Study

Abstract Congenital absence of a tooth is known as dental agenesis or agenesis of a tooth. Although both deciduous and permanent dentition are prone to agenesis, permanent third molars are the most commonly affected teeth. Aim: The aim of this study was to estimate the prevalence of third molar agenesis in the South Indian-based population. Materials and Methods: Three hundred subjects (150 males and 150 females) with a range between 18 and 25 years who had no previous history of third molar extractions and who had other dental complaints that required radiographic investigation using orthopantomograms were selected for the study. The digital radiographs were assessed for the identification of third molar agenesis. The data such as gender and presence of third molar agenesis and site were recorded and statistically tested using the Chi-squared test. Results: The prevalence of third molar agenesis in the studied population was 24.3%. Agenesis of third molars is more prevalent in females than males (P = 0.001). However, there was no significant difference noted between the right and left maxillary and mandibular third molars among males and females (P > 0.05). Conclusion: Based on our findings, third molars are found to be highly vulnerable to dental agenesis, especially in females.

Erzincan Bölgesinde Yaşayan Çocuklarda Üçüncü Molar Dişlerin Konjenital Eksikliğinin Araştırılması

Background:In this study, it was planned to retrospectively determine the congenital deficiencies of the third molars in 1460 panoramic films of pediatric patients in the Erzincan region and to examine the distribution according to gender and location in the jaws. Methods:This retrospective study was conducted at Erzincan Binali Yıldırım University, Faculty of Dentistry from June 2018 - January 2020. 1460 patients(752 females and 708 males) between the ages of 10-14 were studied with panoramic radiograph to assess for agenesis of mandibular third molars. Statistical data were analyzed in SPSS 22 program. The Pearson chi-square test was performed for determining the prevalence of congenitally agenesis of the third molar teeth. Results:The prevalence of third molar teeth agenesis was 35.6 %. Total numbers of patients with single third molar missing were 222(15.5 %). The ratio of the prevalence of third molar agenesis for females(38 %) was higher than that for males(33 %). Significantly more third-molar teeth were found to be missing from the maxilla(57 %) than the mandible(43 %). 529 patients(54 %) had agenesis only on the right side and 469 patients(46 %) had agenesis only on the left. Conclusion:The agenesis of the third molars was investigated in pediatric patients living in Erzincan province and its prevalence was found 35.6 %. Congenital deficiency of the third molar teeth is more common in women, while it has been observed more in the maxilla than in the mandible. More comprehensive studies can be done by increasing the number of individuals examined.

Prevalence of Third Molar Agenesis in Patients—A Panoramic Retrospective Study

Prevalence of Third Molar Agenesis in Patients—A Panoramic Retrospective Study

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

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

Prevalence of Third Molar Agenesis in Patients – A Panoramic Retrospective Study

Background/Purpose: Agenesis is found to be the most common dental anomaly affecting at least 25% of the population. Agenesis is an anomaly where the tooth germ fails to differentiate completely into dental tissues resulting in congenitally missing teeth. The aim of this study was to determine the prevalence of bilateral agenesis of mandibular second premolars. This study also reflects upon the treatment options available for the agenesis of mandibular second premolars.
 Materials and Methods: Bilateral agenesis was considered as agenesis and unilateral agenesis was excluded from the study. Orthopantamograms (OPGs) of 945 dental patients aged 6 years -30 years were examined for the agenesis of teeth. Descriptive statistics were used to describe the percentages and frequencies were calculated using chi square test and the level of significance was considered if p value was <0.05.
 Results: The prevalence of bilateral agenesis or congenitally missing mandibular second premolars were at 10.5%.
 Conclusions: The prevalence rates of bilateral agenesis or congenitally missing mandibular second premolars are more common in males than females. A well informed evidence based decision should be taken for the clinical management of the missing mandibular second premolars.

Association between Third Molar Agenesis and Other Dental Anomalies

Introduction: Third molar teeth are the most common teeth with agenesis. The absence of this tooth also increases the probability of anomalies in other teeth by several times. Since panoramic radiography is used to diagnose and plan treatment in orthodontic patients, along with routine clinical examination, this study aimed to determine the prevalence of third molar agenesis and incidence of other associated anomalies in comparison to that reported for the non-agenesis group using panoramic radiographs. Materials and Methods: In this descriptive-analytical study, the pretreatment records of 562 patients were randomly collected. Out of these subjects, 538 patients were selected based on inclusion and exclusion criteria. The panoramic radiographic images of patients who did not have at least one third molar were assessed with regard to the presence of other dental anomalies, such as dental agenesis, hypodontia, hyperdontia, impacted canine, peg-shaped lateral incisors, ectopic eruption, microdontia, dilaceration, transposition, and transmigration. The prevalence of these anomalies was compared to that of a randomized control group selected from patients with the presence of each four third molars. Results: Out of 538 studied panoramic radiographs, overall, 13.7%, 13.5%, 13.4%, 5.9%, 2.7%, and 1.4% of them had at least one third molar agenesis, canine impaction, peg-shaped lateral incisors, missing teeth, transposition, and hyperdontia, respectively. The frequency rates of impaction and missing teeth were higher in the agenesis group (30% and 40.5%) than those reported for the control group (16% and 2.7%) (p >0.001), respectively. The presence or absence of other dental anomalies was not statistically significant between the two groups and two genders. In addition, the present study demonstrated that the probability of the presence of at least one type of other dental anomalies was higher in individuals with third molar agenesis in comparison to that reported for the control group (p >0.001). Conclusion: Among different types of dental anomalies in the studied population, the probability of impaction and missing teeth was higher in the third molar agenesis group than that of the control group. Furthermore, the prevalence of third molar agenesis was not different between the two genders.

Evidence of dental agenesis in late pleistocene Homo

ObjectiveDifferential 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. Materials139 Late Pleistocene human remains and 149 individuals from three Epi-Paleolithic/ Holocene non-agricultural comparative collections. MethodsAll remains were visually and radiographically recorded by the author. ResultsIn 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. ConclusionsAn 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. SignificanceThird 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. LimitationsPaleolithic 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 ResearchHypotheses on some of the potential selective forces acting on dental size reduction and subsequent agenesis could be tested in recent humans.

Radiographic Assessment of Third Molars Agenesis Patterns in Young Adults

Objective: To determine the prevalence of third molar agenesis and associated characteristics. Material and Methods: A total of 2374 panoramic radiographs were retrieved from the radiological archives and evaluated in a computer monitor under optimum viewing conditions. The basic demographic data (age and sex) and the primary findings regarding the presence or absence of third molars in the maxillary and mandibular arches were recorded systematically in a specially designed proforma. Categorical variables were compared using the Chi-square test. Results: A total of 2000 panoramic radiographs were included in the study, of which 1004 were females (50.2%), and 996 were of males (49.8%). The incidence of third molar agenesis was 486 patients (24.3%). Maxillary third molar showed a higher prevalence of agenesis (28.8%) than mandibular third molars (16.4%) . A total of 1514 patients (75.7%) had third molars in all four quadrants, and the remaining 486 patients (24.3%) had agenesis of third molar tooth in at least one of the quadrants. Single tooth agenesis was observed in 219 (11%) patients, two teeth agenesis in 172 (8.6%) patients, three teeth agenesis in 39 (2%) patients, and four teeth agenesis in 56 (2.8%) patients. Conclusion: The present study exhibited a maximum number of single tooth agenesis. It was also observed that maxillary third molar agenesis is more than the mandibular third molar and the right side is more than the left side. Agenesis of the third molar is more prevalent in males as compared to females.

Third molar agenesis in modern humans with and without agenesis of other teeth.

BackgroundThe number of teeth in the human dentition is of interest both from developmental and evolutionary aspects. The present case-control study focused on the formation of third molars in modern humans aiming to shed more light on the most variable tooth class in the dentition.Materials and MethodsFor this reason, we investigated third molar formation in a sample of 303 individuals with agenesis of teeth other than third molars (agenesis group) and compared it to a sex and age matched control group of 303 individuals without agenesis of teeth other than third molars.ResultsThe prevalence of third molar agenesis in the agenesis group was 50.8%, which is significantly higher than the 20.5% in the control group (p < 0.001). The chance of a missing third molar in the agenesis group was increased by 38.3% (p < 0.001), after controlling for the agenesis in other teeth factor. When considering the amount of missing third molars per individual, a clear tendency towards more missing third molars was evident in the agenesis group compared to the control group. The frequency of bilaterally missing third molars in the agenesis group was 29% in the maxilla, as well as in the mandible, which is about three times higher than the frequency of unilaterally missing third molars (p < 0.001). In the control group, bilaterally missing third molars occurred in 8.6% in the maxilla and 8.9% in the mandible.ConclusionThe present results indicate that genetic factors involved in tooth agenesis affect also the dentition as a whole. Furthermore, the third molars are more vulnerable to factors involved in agenesis of other teeth and they are more often affected as a whole. These findings seem to be associated with the evolutionary trend in humans towards reduced molar number.

Agenesia de terceros molares y su asociación con otras anomalías dentales en una población peruana.

Objective: The purpose of the present study was to determine the association between agenesis of the third molar and other dental anomalies. Materials and Methods: This was an observational, retrospective, cross-sectional and analytical study. The sample included 367 patients, aged 14 to 20 years old with adequate digital panoramic radiography. Patients with syndromes, who had extractions of any third molar and with orthodontic treatment prior to panoramic radiographic examination, were excluded. For data collection, each radiograph was recorded with patient code, sex and age. Results: The prevalence of third molar agenesis was 20.71%. Subsequently, patients were divided into two groups, with agenesis of at least one third molar and a control group; the prevalence of other dental anomalies was 48.69% of third molar agenesis group and 21.31% in the control group. A highly significant association was found between the presence of third molar agenesis and the presence of other tooth abnomalities (p= 0.0000; contingency coefficient = 0.2425).The most frequent dental anomaly was dental inclusion with 20.44% of the population studied; followed by the agenesis of other teeth (7.90%) and finally the presence of supernumerary teeth (1.63%). Conclusions: This study demonstrates that there is an association between third molar agenesis and other dental abnormalities, with a higher prevalence of dental abnormalities in patients with third molar agenesis.

Third molar agenesis: Prevalence and Association with agenesis of other teeth in a Turkish population.

Tooth agenesis is the congenital lack of one or more primary or permanent teeth and it is the most frequently seen dental anomaly. The prevalence of third molar agenesis is significantly higher than the agenesis of other teeth varying from 10% to 40% and shows geographical variance. The aim of this study was to investigate the prevalence of third molar agenesis and its association with other tooth agenesis of jaws. A total of 594 Turkish subjects with or without agenesis of third molars (M3) were included in the study. Dental records and panoramic radiographs were evaluated for M3 agenesis, hypodontia and hyperdontia. Significant differences in the prevalence rate of M3 agenesis between genders among with evaluation of coexistence of M3 and other tooth agenesis were determined by Fisher's exact test. The prevalence of M3 agenesis was determined as 28.7% with no statistically significant gender or location difference. Most common form of M3 agenesis involved one molar followed by two, four and three molars. Agenesis of other teeth was seen among both patient groups with and without M3 agenesis, without significant difference. Turkish population with M3 agenesis did not show increased prevalence of other tooth agenesis, indicating no association between occurrence of agenesis of other teeth and M3.

Relationship between skeletal malocclusion and dental anomalies in Nepalese population

Introduction: Teeth eruption is important for the development of alveolar process which increases vertical height of the face and third molar is the last tooth to erupt in the oral cavity after birth. The aim of this study was to determine relationship between skeletal malocclusion and dental anomalies in Nepalese population.&#x0D; Materials &amp; Method: A sample of 170 patients with agenesis of at least one third molar was divided into four groups according to the third-molar agenesis pattern. Panoramic radiographs, lateral cephalograph and cast models were used to determine the skeletal malocclusion and associated dental anomalies. The Pearson chi-square test was used for stastical analysis.&#x0D; Result: Among 170 patients more than half of the patients were female with the average age being 18.15 ± 3.64 years. Majority of the patients had Class I skeletal malocclusion followed by Class II and III but on group wise comparison of patients with different skeletal patterns Class I skeletal malocclusion had highest prevalence of dental anomalies followed by Class III and Class II malocclusion.&#x0D; Conclusion: Prevalence of third-molar agenesis was more in skeletal class I malocclusion followed by class II and III but skeletal Class I malocclusions had more dental anomalies followed by class III and class II malocclusion.

Third molar tooth agenesis and pattern of impaction in patients with palatally displaced canines.

To investigate the association between third molar agenesis and pattern of impaction, missing teeth, and peg-shaped lateral incisor with palatal canine displacement (PDC). The pretreatment orthodontic orthopantomograms of 438 patients (122 males and 316 females) diagnosed with PDC were included. A total of 338 patients with normally erupted canines who had a preexisting radiograph as part of their orthodontic treatment (125 males and 313 females) served as controls. Orthopantomograms were evaluated for missing third molars, third molar eruption status, and type of impaction, third molar spaces, third molar width, and angulation. In the PDC group, at least one third molar was missing in 48% and 19% in the upper and lower arches, respectively. Also, 38% and 67% of PDC patients had at least one third molar impaction in the upper and lower arches, respectively. The difference between the PDC and control groups was significant for both missing and impacted third molars ( P < .001 for each). The most common type of third molar impaction in the upper arch was vertical and distoangular in the PDC and control groups, respectively. Upper and lower third molar width and spaces were reduced in PDC patients when compared with the control group ( P < .001). In PDC patients, missing teeth and peg-shaped lateral incisors were recorded in 5.6% and 9.1%, respectively. PDC patients showed a high prevalence of third molar agenesis and impaction. Upper and lower third molar width and space were reduced in the PDC patients. There were no significant associations between tooth agenesis (other than third molars) and the PDC anomaly.

Impact of genetics on third molar agenesis

The purpose of this investigation was to determine the impact of heritability on third molar agenesis in twins. The study sample consisted of 284 same sex twins (172 monozygotic and 112 dizygotic), whose mean ages were 19.7 ± 4.3 and 18.9 ± 4.8 years, respectively. The monozygotic group consisted of 36.3% males and 63.7% females, while the dizygotic group consisted of 50.1% males and 49.9% females. The zygosity of the twins was established using 15 specific DNA markers. The prevalence of third molar agenesis in monozygotic twins was 19.6%, which was higher than in the dizygotic twins group (15.50%) (p = 0.004). In both groups, third molar agenesis was more frequent in the maxilla than in the mandible (p = 0.000). Agenesis of the maxillary third molars was mostly affected by additive genetic factors (62–63%), with the common environment and the specific environment accounting for up to 25% and 13%, respectively. In contrast, agenesis of the lower third molars was associated with a higher additive genetic determination (81–83%), with the specific environment accounting for 17% to 19%. The study’s conclusion is that the formation of the third molars follicle is strongly controlled by additive genetic factors.

Radiographic Evaluation of the Presence/Agenesis of Third Molars in a Mexican Child Population

In the human being, third molar is the tooth that exhibits more variants during its embryologic development, usually causing diverse anomalies and discomfort when erupting to the oral cavity. It has been pointed out that the prevalence of third molar agenesis is between 9 to 37%. The aim of the present comparative cross-sectional study was to radiographically assess the presence/absence of third molar germs (G3M) in a sample of pediatric patients of Mexican origin. A total of 513 panoramic radiographs were analyzed from patients attending the Pediatric Dentistry Postgraduate Program ( San Luis Potosí University, México), during the years 2011 to 2017. Inclusion criteria were patients between 7 and 18 years old, any gender; children with antecedents of a third molar extraction, previous orthodontic treatment, or with an associated congenital or systemic condition were excluded. Total prevalence G3M agenesis was calculated. Then, statistical comparisons of agenesia proportions per dental quadrant, gender, and age group were performed. 245 panoramic radiographs corresponded to the female gender, while 268 belonged to the male gender. The total prevalence of G3M agenesia was estimated in nearly 56%, and the 7-8 years old group exhibited the highest proportion; however, when this age group was excluded from the analysis, such prevalence decreased to 27.3%. Both mandibular quadrants showed higher proportions of G3M agenesia. There were no significant differences between genders. The total prevalence reported in the present study was found to be well above regarding the international parameters. It is quite possible that lack of radiographic visualization of G3M had been inaccurate in some cases due to the common absence of calcification traces from those teeth during early ages (7-8 years old). The adjusted analysis provided a prevalence value more in line with the recognized standards in the dental literature.

Obeservations on association between third molar agenesis and craniofacial morphology

This study was designed to examine the relationship between third molar agenesis and skeletal morphology in the Chinese population. A total of 1043 patients' records were analyzed with panoramic radiographs and cephalograms. Congenitally missing third molars were assessed with respect to gender, jaw, and side, and assessed in various types of facial morphology. Linear, angular, and proportional cephalometric measurements were analyzed and compared among the samples. For the evaluation of results, the following statistics were used: the Pearson χ 2 test, one-way ANOVA, and the Student-Newman-Keuls method. The overall prevalence of third molar agenesis was 28.7%. Missing third molars were more common in the maxilla and on the right side, while the difference was not statistically significant (P>0.05) between genders. Every hypodontia group had a smaller SN-GoGn angle, Y-axis-FH angle, and a larger S-Go/N-Me ratio. The group with third molar agenesis in both jaws had smaller SNA and Wits values. The frequency of third molar agenesis in subjects with a Class II malocclusion was significantly lower than in other types of malocclusion (P<0.05), and the incidence of third molar agenesis in hypodivergentgrowth pattern was higher than in other patterns (P<0.05). The results demonstrate a possible association between third molar agenesis and both sagittal and vertical craniofacial morphology.

Prevalence of Third Molar Agenesis between the Individuals of Kerala and Bhutan: A Comparative Study

Aim: The aim of the study was to evaluate the prevalence of the third molar agenesis in Keralites and Bhutanese groups of individuals. Materials and Methods: One hundred and seven panoramic radiographs retrieved from the department of oral medicine and radiology were analyzed, which included 55 individuals from Kerala and 52 individuals from Bhutan within the age range of 18–25 years. The prevalence of third molar agenesis between individual dentition quadrants, upper and lower jaw, and right and left side of the dentition were examined and compared between the two groups. The data was analyzed using student's un-paired t-test and Chi square test. Results: Prevalence of third molar agenesis among 107 participants was 28.9%. It was more in Bhutanese (35.29%) compared to Keralites (23.63%). The association of females with agenesis was found to be more than males in both the groups (61.1% females in Bhutanese and 69.2% females in Keralites). Third molar agenesis was found to be more prevalent in maxillary arch as compared to the mandibular arch. The association of third molar agenesis with age and sex in both the groups was statistically not significant (P > 0.05). Incidentally, we found 0.9% of second molar agenesis bilaterally in Bhutanese. Conclusion: Third molar agenesis was higher among Bhutanese as compared to Keralites.

A radiographic survey of agenesis of the third molar: A panoramic study.

Purpose:It is a well-known fact that nature tries to eliminate what is not in use. Because of this, the number of certain teeth which are no longer necessary for function are either getting increasingly impacted or are not developing at all. This is especially the case where third molars are concerned. Furthermore, the presence or absence of the third molar is significant to all branches of dentistry and in particular, forensic dentistry.Objectives:The objectives of this study is to assess (1) The prevalence of third molar agenesis in population of age group 18–25 years. (2) The genderwise difference of third molar agenesis. (3) The difference between maxilla and mandible.Materials and Methods:Dental patients, who are advised or referred for orthopantomograph, visited to the Department of Oral Medicine and Radiology were included in the study. The study population comprised 300 patients.Statistical Analysis:The data obtained was tabulated and subjected to statistical analysis. SPSS version 17 software was used for the analysis of the data. The Chi-square test was used for the same.Results:The incidence of agenesis of the third molar is significantly higher for tooth number 18 (P < 0.001). Overall, it is significantly higher among females compared to the males (P < 0.001) in our study population.Conclusion:(1) The present study reports 46.7% agenesis of the third molar. (2) The frequency of third molar agenesis was found significantly greater in the females. (3) Third molar agenesis showed a greater predilection in maxilla compared to mandible.

Epidemiological survey on third molar agenesis and facial pattern among adolescents requiring orthodontic treatment.

BackgroundThe aim of this study was to determine the association between facial pattern according to Ricketts cephalometric analysis, and prevalence of third molar agenesis, taking subject age and gender as control variables.Material and MethodsAn epidemiological survey was conducted based on a sample of 224 candidates for orthodontic treatment aged 12 to 24 (n=224). Third molar agenesis was recorded using Ricketts cephalometric analyses of lateral teleradiographs and panoramic radiographs. The risk for agenesis was predicted considering the 5 Vert Index parameters (facial axis, facial depth, mandibular plane angle, lower facial height and mandibular arch), facial type (brachyfacial, mesofacial, dolichofacial) and sociodemographic variables (age and sex), using odds ratio (OR) calculated by logistic regression.ResultsThird molar agenesis was observed in 25% of the sample. Risk for agenesis is significantly determined by sociodemographic factors (age, OR: 1.2), cephalic patterns (mesofacial vs dolichofacial, OR:4.3; and brachyfacial vs dolichofacial OR: 3.2) and cephalometric patterns (facial axis, OR: 0.8; lower facial height, OR: 0.8; and mandibular plane angle, OR:0.9).ConclusionsFacial parameters (facial axis, lower facial height, and mandibular plane angle) proved to be strong predictors of the risk for third molar agenesis, the prevalence of agenesis being significantly lower in dolichofacial individuals. Key words:Facial Pattern, Ricketts Analysis, Third Molar Agenesis.