The relationship between third molar agenesis and craniofacial morphology: a systematic review and meta-analysis.

BACKGROUND: Agenesis of third molar agenesis has a higher incidence than other tooth development anomalies. Previous research identified a potential correlation between third molar agenesis and specific craniofacial morphology; however, no systematic review and meta-analysis on this topic currently exists. OBJECTIVE: The objective of this systematic review and meta-analysis was to evaluate the association between third molar agenesis and craniofacial sagittal and vertical morphology. SEARCH METHODS: An electronic search was conducted on PubMed, Embase, Web of Science, and the Cochrane Library without restrictions on publication year or language; this was supplemented by the manual retrieval of relevant literature. SELECTION CRITERIA: Cross-sectional studies that compared craniofacial morphology using angular and linear measurements obtained from lateral cephalography between patients with third molar agenesis and those without were included. DATA COLLECTION AND ANALYSIS: The quality assessment of the enrolled articles was evaluated by the Joanna Briggs Institute critical appraisal tool. Meta-analysis and sensitivity analysis were performed by Review Manager software (The Cochrane Collaborative, version 5.4, Cochrane IMS). RESULTS: A total of seven studies were included. Meta-analysis demonstrated that the ANB (mean differences (MD) = -0.75, 95% CI: -1.31 to -0.19, P < 0.01), palate length (ANS-PNS, MD = -1.68, 95% CI: -2.24 to -1.11, P < 0.01), and mandibular length (Go-Pog, MD = -0.36, 95% CI: -0.59 to -0.13, P < 0.01) were smaller in patients with third molar agenesis. With regard to vertical craniofacial morphology, the mandibular plane angle (MP-FH; MD = -1.88, 95% CI: -3.45 to -0.31, P = 0.02), gonial angle (gonial angle; MD = -1.73, 95% CI: -2.69 to -0.77, P < 0.01) and lower face height (lower face heigh angle; MD = -1.36, 95% CI: -1.94 to -0.77, P < 0.01) were smaller in patients with third molar agenesis, indicating a flatter or brachyfacial skeletal pattern. CONCLUSIONS: The results of this study suggest that third molar agenesis maybe associated with a reduced maxillary length and a flatter mandible. However, these findings need to be interpreted with caution due to inconsistencies in the certainty of evidence. CLINICAL TRIAL REGISTRATION: PROSPERO (CRD42023448226).

Third molar agenesis relates to human craniofacial form.

OBJECTIVE: To investigate the association between the number of third molars and craniofacial shape. SUBJECTS AND METHODS: The study sample comprised 470 individuals (194 males and 276 females), out of whom 310 (124 males, mean age: 14.6 years and 186 females, mean age: 14.1 years) had a full permanent dentition including third molars and 160 (70 males, mean age: 13.7 years and 90 females, mean age: 13.9 years) had at least one missing third molar. Pre-orthodontic treatment cephalometric images were digitized using 127 landmarks to describe the shape of the entire craniofacial configuration, the cranial base, the maxilla, and the mandible. The shapes of the various configurations were described by principal components (PCs) of shape. The effect of third molar agenesis on craniofacial shape was evaluated with multivariate regression models, considering shape PCs as the dependent variables, and age and sex as predictors. RESULTS: There was a strong association between third molar agenesis and the shape of all craniofacial configurations in both sexes. Individuals with missing third molars presented a less convex craniofacial configuration, a shorter anterior facial height and a more retrusive maxilla and mandible. In cases with third molar agenesis only in one jaw, shape differences were also evident in the opposing jaw. LIMITATIONS: Interpretation of study outcomes should take into consideration the two-dimensional data and the analysis of only white-European subjects. CONCLUSIONS: There is a strong association between third molar formation and craniofacial shape. The effect is rather generalized than local and is potentially linked to an ongoing evolutionary mechanism that leads to smaller and fewer teeth, as well as smaller craniofacial configurations, in modern humans.

Germenectomía de los terceros molares con cefalometría predictiva de brote

Introducción: Las complicaciones, asociadas al brote anormal de los terceros molares, es posible evitarlas con la germenectomía de estos dientes. Objetivo: Caracterizar la evolución de la germenectomía de terceros molares en pacientes con diagnóstico cefalométrico de brote anormal. Métodos: Se realizó un estudio observacional, descriptivo y transversal en el Servicio de Cirugía Maxilofacial del Hospital Provincial "Saturnino Lora Torres", desde febrero de 2019 hasta marzo de 2021. Se estudiaron 32 pacientes de 13 a 15 años de edad, interviniéndose quirúrgicamente 78 terceros molares. Las variables fueron edad, sexo, color de la piel, localización y posición del tercer molar; así como las complicaciones trans y posoperatorias y la evolución. Resultados: Entre los 32 pacientes incluidos en el estudio predominó el sexo femenino (62,5 por ciento) y la edad de 14 años (40,6 por ciento). Las complicaciones ocurridas durante la germenectomía fueron más frecuentes en la arcada inferior. Aunque no fueron detectadas diferencias estadísticamente significativas según localización (valor de p>0,05); con 30 transoperatorias para un 38,4 por ciento y 75 posoperatorias para un 96,2 por ciento. Conclusiones: Se evidencia una evolución marcadamente favorable posterior a la germenectomía de terceros molares en la población de pacientes con diagnóstico cefalométrico de brote anormal. En ellos el sangrado transoperatorio y el dolor posoperatorio constituyen las complicaciones a considerar en este tipo de procedimiento quirúrgico(AU)

Introduction: Complications associated with the abnormal eruption of third molars can be avoided with germenectomy of these teeth. Objective: To characterize the evolution of third molar germenectomy in patients with a cephalometric diagnosis of abnormal bud. Methods: An observational, descriptive and cross-sectional study was carried out in the Maxillofacial Surgery Service at Saturnino Lora Torres Provincial Hospital, from February 2019 to March 2021. Thirty two patients aged 13 to 15 years were studied, with 78 third molars undergoing surgery. The variables were age, sex, skin color, location and position of the third molar; as well as trans and postoperative complications and evolution. Results: Among the 32 patients included in the study, the female sex (62.5 percent) and the age of 14 years (40.6 percent) predominated. Complications that occurred during germenectomy were more frequent in the lower arch. Although no statistically significant differences were perceived according to location (p value > 0.05); with 30 intraoperative for 38.4 percent and 75 postoperative for 96.2 percent. Conclusions: There is evidence of a markedly favorable evolution after germenectomy of third molars in the population of patients with cephalometric diagnosis of abnormal bud. In them, transoperative bleeding and postoperative pain are the complications to consider in this type of surgical procedure(AU)

Tercer molar heterotópico, etiología y manejo quirúrgico / Heterotopic third molar, etiology and surgical management

Los terceros molares heterotópicos son dientes que se encuentran incluidos en los maxilares y la mandíbula distantes a su sitio de erupción habitual. Su etiología no está bien definida y existen diversas teorías. Estos dientes pueden aparecer en diferentes zonas de las estructuras óseas, teniendo predilección por la mandíbula. Suelen aparecer entre la segunda y la séptima década de la vida, la mayoría de los casos son hallazgos imagenológicos en la consulta odontológica. El tercer molar mandibular es el diente que presenta heterotopía con mayor frecuencia, siendo su localización habitual en rama mandibular y en la región subcondílea. El quiste dentígero es la patología asociada más común. Presentamos un caso de tercer molar heterotópico en rama mandibular derecha de larga evolución, relacionado a un quiste dentígero, el cual se manejó bajo anestesia regional. Se describe la etiología, técnica quirúrgica y consideraciones especiales relacionados con los dientes heterotópicos (AU)

Heterotopic third molars are teeth that are embedded in the maxilla and mandible, remote from their usual eruption site. Its etiology is not well defined and there are various theories at the moment. These teeth can appear in different areas of the bone's structures, having a predilection for the jaw. They usually appear between the second and seventh decade of life, and in most cases are imaging findings. The mandibular third molar is the tooth with the most frequent heterotopia, being its usual location in the mandibular branch and in the subcondylar region. The dentigerous cyst is the most common associated pathology. We present a case of a long evolution heterotopic third molar in the right mandibular branch, related to a dentigerous cyst which was managed under local anesthesia. The etiology, surgical technique and special considerations related to heterotopic teeth are described (AU)

Evaluation of the frequency of third molar agenesis according to different age groups.

PURPOSE: Third molars (M3s) are the most common congenitally missing teeth. The aim of this study was to compare the frequency of M3 agenesis in two different age groups. METHODS: This study examined the panoramic radiographic images of 1036 patients. Two groups, each consisting of 518 patients, were arranged based on age ranges. The patients aged 12 to 19 years were in the first group and those 20 years and older were in the second group. The frequency of M3 agenesis was examined in both age groups. The distribution of M3 agenesis by sex and jaw was also recorded, along with the number of M3s affected by agenesis. Chi-square tests were used to examine the relationships between categorical variables. RESULTS: M3 agenesis was observed in 29.3% and 20.5% in the first and second groups, respectively; the difference was statistically significant (P < .01). It was more common in female (27.3%) than in male patients (21.4%), and in the maxilla (11.2%) than in the mandible (5.8%), and the differences were statistically significant (P < .05). It was mostly observed forthemaxilla right M3 (18) (30.9%) and in the single quadrant of the jaws (9.7%). CONCLUSIONS: The frequency of M3 agenesis was more common in patients aged 12 to 19 years than in those aged 20 years and older. Additionally, M3 agenesis was more common in females and in the maxilla.

Avaliação de anomalias dentárias em terceiros molares através de tomografia computadorizada de feixe cônico / Evaluation of dental anomalies in third molars using cone beam computed tomography

Objetivo: A proposta deste estudo foi determinar a prevalência das anomalias dentárias em terceiros molares. Materiais e métodos: O estudo foi feito de modo transversal e retros-pectivo através da análise das tomografias computadorizadas de feixe cônico (TCFC) de pacientes com os terceiros molares. As anomalias dentárias foram investigadas e registra-das em tabela previamente desenhada para o estudo. Foram registradas outras informações como: sexo e idade. Resultados:151 exames de TCFC foram incluídos na amostra, totali-zando 308 terceiros molares avaliados. Dos 308 terceiros molares avaliados, 105 apresen-taram anomalias (37,7%). A anomalia dentária mais prevalente foi a dilaceração radicular, apresentando 96 casos (34,5%), seguida de 5 casos de microdontia (1,79%), 3 casos de hi-percementose (1,07%) e 1 pérola de esmalte (0,35%). Conclusão: A partir deste estudo foi observado que as anomalias em terceiros molares são comuns. Além disso, a dilaceração foi a anomalia mais prevalente na amostra estudada, sendo importante o cirurgião-dentista utilizar exames de imagem no planejamento de uma extração dentária.

Objective: The purpose of this study was to determine the prevalence of dental anomalies in third molars. Materials and methods: This cross-sectional and retrospective study analyzed the cone-beam computed tomography (CBCT) of patients with third molars. Dental anomalies were investigated and recorded in a table previously designed for the study. Other information such as sex and age were registered. Results: 151 patients were included in the sample, totaling 308 third molars evaluated. Out of 308 teeth, 105 had anomalies (37.7%). The most prevalent dental anomaly was the root tear, 96 cases (34.5%). The second was microdontia, 5 cases (1.79%); hypercementosis, 3 cases (1.07%); and enamel pearl, 1 case (0 .35%). Conclusion:We observed that third molar anomalies are common and that laceration was the most prevalent anomaly in the sample. Thus, dentists need to use imaging tests in planning a tooth extraction.

Radiographic Assessment of Third Molars Agenesis Patterns in Young Adults

ABSTRACT 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.

Agenesis of third molars and its association with other dental anomalies in a peruvian population / 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.

Objetivo: La presente investigación tuvo como finalidad determinar la asociación que existe entre la agenesia del tercer molar y otras anomalías dentarias. Material y Métodos: El estudio fue observacional, retrospectivo, transversal y analítico. La muestra que incluyó 367 pacientes de 14 a 20 años de edad con radiografía panorámica digital con parámetros adecuados. Se excluyeron pacientes con algún tipo de condición sindrómica, con exodoncias de algún tercer molar y con tratamiento ortodóntico previo al examen radiográfico panorámico. Para la recolección de datos, cada radiografía fue registrada con código de paciente, sexo, edad. Resultado: Se reportó una prevalencia de 20,71% de casos con agenesia de terceros molares. Los pacientes fueron divididos en 2 grupos, con agenesia de al menos un tercer molar y un grupo control, en ambos se calculó la prevalencia las otras anomalías dentarias, la cual fue de 48.69% de los pacientes que presentan agenesia de tercer molar tienen otra anomalía dentaria y 21.31% del grupo control tienen otra anomalía dentaria. Se encontró una asociación altamente significativa entre la presencia de agenesia de tercer molar y presencia de otras anomalías dentales (p=0.0000; coeficiente de contingencia=0.2425). La anomalía dental encontrada con más frecuencia es la inclusión dentaria con 20,44% del total de la población estudiada; seguido de la agenesia de otros dientes con 7,90% y finalmente la presencia de dientes supernumerarios con 1,63%. Conclusion: Este estudio demuestra que existe asociación entre la agenesia de tercer molar y otras anomalías dentarias, existiendo una mayor prevalencia de anomalías dentales en pacientes con agenesia del tercer molar.

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

BACKGROUND: 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. AIMS: The aim of this study was to investigate the prevalence of third molar agenesis and its association with other tooth agenesis of jaws. SUBJECTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Is third molar agenesis an anomaly or just a sign of variation? Prevalence and manner of presentation of this condition in a sample from the Metropolitan Region of Chile / ¿Es la agenesia del tercer molar una anomalía o simplemente un signo de variación? Prevalencia y forma de presentación de esta condición en una muestra de la Región Metropolitana de Chile

Agenesis of permanent teeth is the most frequent dental anomaly. The most affected tooth is the third molar (M3), and its congenital absence poses interesting questions from a clinical and evolutionary perspective. M3 agenesis can occur isolated or as part of syndromes. Researchers have reported prevalences that vary largely among populations, between 5 % and 56 %, with a mean prevalence of 22.6 %. Previous Chilean studies, mainly in Northern populations, have determined a prevalence between 19.8 % and 26.7 %. The aim of this work was to assess the prevalence of M3 agenesis and to characterize its presentation in a sample from Santiago, the largest to date in a M3 agenesis prevalence study in Chile. In this study, 535 panoramic radiographies and clinical histories of patients from the Dental Clinic of the Universidad de Chile were used to determine prevalence and distribution according to sex, affected tooth, and location (left or right; maxilla or mandible). The Chi-square test was used to assess statistical significance in distribution. The calculated M3 agenesis prevalence was of 12.89 %. No statistically significant differences were found between sexes, sides or location within the jaws. The agenesis of one third molar was more common, then two, three and finally of all the third molars. The prevalence of M3 agenesis in the sample is 12.89 %, with a random manner of presentation. We propose that as it currently stands, M3 agenesis should be considered an anatomical variation rather than a developmental anomaly.

La agenesia de dientes definitivos es la anomalía dental más común. El diente más afectado es el tercer molar (M3), y su ausencia congénita plantea preguntas interesantes desde una perspectiva clínica y evolutiva. La agenesia de M3 puede ocurrir de manera aislada o asociada a síndromes. Estudios a nivel mundial reportan una prevalencia variable entre poblaciones: 5 % a 56 %, con una prevalencia media del 22,6 %. Estudios chilenos anteriores, principalmente en poblaciones del norte, han determinado una prevalencia entre 19,8 % y 26,7 %. El objetivo de este trabajo fue determinar la prevalencia de agenesia de M3 y caracterizar su presentación en una muestra de Santiago, la más grande hasta la fecha en un estudio de prevalencia de agenesia de M3 en Chile. Se utilizaron 535 radiografías panorámicas y antecedentes de pacientes atendidos en la Clínica Odontológica de la Universidad de Chile para evaluar la prevalencia y modo de presentación de la agenesia de M3. Se analizó su distribución según ubicación, sexo y simetría, mediante test estadístico Chi-cuadrado. Se calculó una prevalencia de agenesia de M3 de 12,89 %, sin un patrón claro ni estadísticamente significativo en su distribución. Fue más común la agenesia de un tercer molar, luego de dos, tres y finalmente de todos los terceros molares. La prevalencia de agenesia en una muestra de la Región Metropolitana es de 12,89 % y su distribución es aleatoria según la ubicación, sexo y simetría. Se propone que esta condición actualmente debiera considerarse como una variación anatómica más que a una anomalía del desarrollo.

Prevalence of Agenesis of Mandibular Third Molars in A Tertiary Healthcare Centre of Nepal.

INTRODUCTION: Racial variation, genetic inheritance and various other factors can affect the jaw size and ultimately the tooth size and number. Studies for agenesis of mandibular third molars have been carried out in various populations but the data relating to these are not evident from most of the parts of Nepal. Hence, the objective of the present study is to determine the prevalence of agenesis of mandibular third molars among the population of patients visiting the Department of Oral Medicine and Radiology of B. P. Koirala Institute of Health Sciences. METHODS: This descriptive cross-sectional study was conducted at Department of Oral Medicine And Radiology, College of Dental Surgery, B. P. Koirala Institute of Health Sciences from September 2015 to September 2016 after taking ethical approval from Institutional Review Committee. Two hundred and eighty four patients (568 sites of third molar bilaterally), visiting the Department of Oral Medicine and Radiology were studied with Panoramic Radiograph to assess for agenesis of mandibular third molars bilaterally. Data was entered in Microsoft Excel sheet and transferred to Statistical Package for the Social Sciences version 11.5. RESULTS: Out of 284 participants, 568 sites of mandibular third molars were evaluated and agenesis was seen among 163 (28.7%) participants at the confidence interval of 95% (28.643 to 28.757). Total numbers of patient with single missing mandibular third molar were 35 (6.2%). Twenty one had agenesis only on the right side and 14 had agenesis only on the left. The total number of patients with agenesis of both the mandibular third molars was 64 (22.5%). CONCLUSIONS: Agenesis was highly prevalent in this study group. The likelihood of third molar being absent on one side, when there was concurrent missing third molar on the other side of mandible was also high.

Tooth agenesis patterns in Japanese orthodontic patients with nonsyndromic oligodontia.

INTRODUCTION: Tooth agenesis is the most common dental anomaly in humans and is often found in orthodontic patients. However, severe tooth agenesis (oligodontia) is rare and its characteristics are poorly understood. This study aimed to investigate tooth agenesis patterns of Japanese orthodontic patients with nonsyndromic oligodontia. METHODS: Panoramic radiographs of 228 orthodontic patients (141 females, 87 males) with nonsyndromic oligodontia were selected and permanent tooth agenesis excluding third molars was evaluated. Influence of cutoff age was tested, tooth agenesis patterns for each quadrant were calculated, and antagonistic maxillary and mandibular quadrants were merged as the occluding tooth agenesis pattern. Full-mouth tooth agenesis patterns were also evaluated. RESULTS: The highest prevalence of tooth agenesis was observed in maxillary and mandibular second premolars, followed by maxillary first premolars. Prevalence of a symmetric pattern between right and left quadrants was significantly higher than matched patterns between maxillary and mandibular antagonistic quadrants. Among 456 possible tooth agenesis patterns, 51 and 49 patterns were observed for the maxillary and mandibular quadrants, respectively, but 215 patterns for the occluding patterns were observed. In addition, 180 full-mouth tooth agenesis patterns were observed in the 228 patients. CONCLUSIONS: Distinct characteristics in highly ranked patterns were observed compared with studies from other geographic areas, especially in the maxillary arch. Occluding and full-mouth tooth agenesis patterns showed wide variation, suggesting difficulty in orthodontic diagnosis.

Tratamento cirúrgico de terceiro molar inferior invertido: relato de caso / Treatment of third invested lower molar: case report

A presença de terceiros molares invertidos se apresenta como uma condição pouco relatada na literatura. Diversas hipóteses têm sido propostas para explicar o deslocamento destes elementos, entretanto suas causas e tratamentos permanecem incertos. O objetivo deste trabalho é relatar um caso clínico de impacção invertida de terceiro molar inferior direito, onde optou-se pela exodontia sob anestesia local com osteotomia conservadora e exérese total do elemento em paciente do sexo feminino de 52 anos. Terceiros molares com esta variação de erupção são raros na clínica, sendo geralmente visualizados em exames radiográficos de rotina e observados clinicamente após início de sintomatologia. Diversos tratamentos têm sido propostos, variando de abordagem cirúrgica, ao acompanhamento de longo prazo. A abordagem intraoral associada a uma conduta conservadora tem se mostrado o tratamento de escolha na maioria dos casos. Entretanto, a escolha do planejamento dependerá, dentre outros fatores, da sintomatologia do paciente e a presença de patologias associadas, sempre optando-se pela técnica que promoverá menor morbidade operatória e melhor resolubilidade do caso(AU)

The presence of inverted third molars presents as a condition poorly reported in the literature. Several hypotheses have been proposed to explain the displacement of these elements, however their causes and treatments remain uncertain. The objective of this study is to report a clinical case of inverted impaction of the right lower third molar, where it was chosen exodontia under local anesthesia with conservative osteotomy and total exeresis of the element in a 52-year-old female patient. Third molars with this variation of eruption are rare in the clinic and are usually visualized in routine radiographic examinations and observed clinically after start symptomatology. Several treatments have been proposed, ranging from a surgical approach to long-term follow-up. The intraoral approach associated with conservative management has been shown to be the treatment of choice in most cases. However, the choice of planning will depend, among other factors, on the patient's symptoms and the presence of associated pathologies, always opting for the technique that will promote less operative morbidity and better solubility of the case(AU)

The assesment of relationship between the angulation of impacted mandibular third molar teeth and the thickness of lingual bone: A prospective clinical study

Background: Our purpose was to investigate the relationship between the angulation of mandibular third molars and the thickness of the lingual bone, which can affect the risk of lingual nerve damage during lower third molars surgical extraction. Material and Methods: This study consisted of 104 patients (42 males and 62 females), aged between 18-42 years (24.67 ± 6.11 years). Cone Beam Computed Tomography (CBCT) images were taken for preoperative assessment. The teeth were divided into four groups according to their positions: mesioangular, distoangular, vertical and horizontal. Lingual bone thickness around impacted teeth were measured at three points: cementoenamel junction (CEJ) of the mandibular second molar, mid-root of the impacted third molar, and apex of the impacted third molar root. Two predisposing factors of lingual nerve damage were recorded: lingual bone perforated by the impacted tooth and lingual bone thinner than 1 mm. Additionally, buccolingual angulations of the teeth in each group were measured. Impacted mandibular third molars were removed in usual way. One week after surgery, the patients were evaluated regarding lingual nerve paresthesia. Results: None of the 104 patients experienced paresthesia, including the ones who had teeth with close proximity with lingual nerve. The mean thickness of bone was 1.21±0.63 mm at CEJ of the second molar; 1.25±1.02 mm at the mid-root; and 1.06±1.31 mm at the apex. Horizontally impacted teeth had thinner lingual bone at mid-root level (p=0.016). Buccolingual angulated teeth were more often associated with perforated lingual bone (p=0.002). Buccolingual and mesial/distal angulation had negative correlation with lingual bone thickness (p<0.05). Conclusions: As the buccolingual and mesiodistal angulations increase, lingual bone thickness decreases. Horizontally impacted teeth seemed to compromise the integrity of the lingual bone more than impacted teeth in other positions. During the surgery, thin or perforated lingual bone may result in displacement of the impacted tooth lingually

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Terceiro molar impactado invertido: série de casos retrospectivos e relato de dois casos / Inverted impacted third molars: retrospective case series and two case reports

Dente impactado é todo aquele que sofre falha no seu processo eruptivo, ficando sob tecido duro e/ou mole. Dentro da classificação de tais dentes existem os terceiros molares invertidos, poucos descritos na literatura. O objetivo deste artigo é apresentar dois casos de terceiros molares maxilares impactados invertidos, diagnosticados através de exames de rotina odontológica e analisar relatos na literatura sobre terceiros molares invertidos. Foram selecionados artigos anexados à base de dados Pubmed, através de busca pelo termo "Inverted Third Molar", não havendo restrição quanto ao ano de publicação e idioma. Terceiros molares invertidos apresentam rara prevalência, sendo este relato um complemento à literatura previamente publicada(AU)

Impacted tooth is anyone who suffers failure in eruptive process, getting under hard and/or soft tissue. According to this classification there are the third inverted molars, few described in the literature. The aim of this article is to present two cases of inverted impacted maxillary third molars, diagnosed through routine dental examinations and to analyze reports in the literature about inverted third molars. We selected articles attached to the Pubmed database, searching for the term "Inverted Third Molar", there being no restriction regarding the year of publication and language. Inverted third molars present a rare prevalence, being this report a complement to previously published literature(AU)

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.

Association between skeletal morphology and agenesis of all four third molars in Japanese orthodontic patients.

The purpose of this study was to clarify differences in skeletal morphologies between male and female orthodontic patients with and without agenesis of all four third molars. A total of 64 patients (32 males and 32 females) with agenesis of all four third molars without agenesis of other teeth were selected as the third molars agenesis group (group 1). In addition, 64 patients (32 males and 32 females) with all these teeth were selected as controls (group 2). Lateral cephalograms taken between the ages of 14 and 30 years were used to compare skeletal morphology between groups 1 and 2 and between sexes. Maxillary length (P < 0.001), lower facial height (P < 0.05), gonial angle (P < 0.001) and mandibular plane angle (P < 0.001) were significantly smaller in group 1 than in group 2. Irrespective of the presence or absence of all four third molars, males had significantly smaller lower facial height (P < 0.01) and mandibular plane angle (P < 0.001) and significantly greater total mandibular length (P < 0.001), mandibular body length (P < 0.001) and mandibular ramus height (P < 0.001) than females. Japanese orthodontic patients with agenesis of all four third molars had significantly small maxillary length, lower facial height, gonial angle and mandibular plane angle.

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.