Prevalence and morphological analysis of dens invaginatus in anterior teeth using cone beam computed tomography: A systematic review and meta-analysis.

OBJECTIVES: To evaluate the prevalence and morphological characteristics of DI using CBCT. METHODS: A literature search was performed in PubMed, Embase, Scopus, and Web of Science. Inclusion criteria were randomized clinical trials, cross-sectional studies, and prospective and retrospective cohort studies evaluating the morphological characteristics of DI in anterior teeth using CBCT. Three reviewer authors independently screened the studies, applied the eligibility criteria, assessed the risk of bias, and extracted until September (2022). The risk of bias was evaluated using the Joanna Briggs Institute criteria. Meta-analyses of proportions were used for estimate the prevalence DI according to factors at participant and tooth levels. RESULTS: Six studies were included in the meta-analysis. Among 7373 individuals, a prevalence of 7.45 % of DI was observed (n = 258; τ2 = 0.0096; CI of 4.51-11.3; p < 0.05), with no significant influence of sex. Regarding laterality, unilateral DI showed higher mean prevalence (4.30 %; CI of 2.03-7.33). Among the 382 anterior teeth with DI (0.72 %), the most affected tooth was the upper lateral incisor (5.12 %; n = 329; CI of 2.35-8.86; p < 0.001), type I was the most prevalent (0.59 %; CI of 0.24-1.08) and the presence of open apex and periradicular pathology ranged from 4.3 % to 22.72 % and 3.5-77.92 %, respectively. CONCLUSIONS: The prevalence of individuals with dens invaginatus was 7.45 %, the most affect tooth was the upper lateral incisor with a prevalence of 5.12 % unilaterally and type I was the most prevalent morphology.

Prevalence of dens invaginatus and its association with periapical lesions in a Western Indian population-a study using cone-beam computed tomography.

OBJECTIVES: This study aimed to assess the prevalence of dens invaginatus (DI) and its association with periapical lesions (PLs) in a Western Indian population by means of cone-beam computed tomography (CBCT). MATERIALS AND METHODS: CBCT volumes of 5201 subjects were evaluated. Associations among gender, tooth type, DI type (Oehler's classification), and presence of PL were investigated. PL was codified using Estrela's Cone Beam Computed Tomography Periapical Index (CBCTPAI). Chi-square tests and descriptive statistics were used at p = 0.05. RESULTS: Overall, 7048 CBCTs were assessed, containing 19,798 maxillary and mandibular anteriors, of which 77 maxillary teeth demonstrated DI (0.39% of all anteriors). Of all 5201 subjects, 57 had DI (1.1%). Bilateral DI was more common in females than in males (p = 0.046). DI type distribution was as follows: type I (22.1%), type II (61.03%), type IIIa (10.4%), and type IIIb (6.5%), which was significantly different (p < 0.001). Maxillary lateral incisors were the most associated with PL (p < 0.001). Type I was frequently associated with CBCTPAI scores 1 and 2 (absence of PL), whereas types II, IIIa, and IIIb were associated with CBCTPAI scores 3, 4, and 5 (presence of PL). CONCLUSIONS: A prevalence of 1.1% identifies DI as a common developmental tooth anomaly in a Western Indian subpopulation. The percentage of maxillary anteriors affected by DI and associated PLs should be considered before diagnosis and treatment planning. CLINICAL RELEVANCE: Knowledge about the prevalence of DI and its subtypes, and their association with/without periapical pathosis may aid clinicians in treatment planning and execution to improve patient outcomes.

Fusión del tercer molar inferior con un cuarto molar: reporte de tres casos / Fusion of the lower third molar with a fourth molar: report of three cases

Los dientes supernumerarios y la fusión dental son anomalías del desarrollo dental cuyas causas aún no se han dilucidado con certeza. El cuarto molar inferior, también denominado distomolar, es uno de los dientes supernumerarios con menor frecuencia de aparición clínica y su fusión con el tercer molar es una condición todavía menos común. A continuación, se reportan los casos clínicos de tres pacientes masculinos que presentaron fusión del tercer molar inferior derecho con un distomolar tratados mediante odontectomía (AU)

Supernumerary teeth and dental fusion are abnormalities of dental development whose causes have not yet been elucidated with certainty. The lower fourth molar, also called distomolar, is one of the supernumerary teeth with the least frequency of clinical appearance and its fusion with the third molar is an even less common condition. Next, the clinical cases of three male patients who presented fusion of the right lower third molar with a distomolar treated by odontectomy are reported (AU)

Investigation of dens invaginatus in a Chinese subpopulation using Cone-beam computed tomography.

OBJECTIVE: This study assesses the prevalence and characteristics of dens invaginatus (DI) in a sample of Chinese population by using cone-beam computed tomography (CBCT) images. METHODOLOGY: A retrospective study was conducted by using the CBCT images of 1,004 patients. The whole dentition was evaluated for the presence and characteristics of DI. Periapical pathosis status and bilateral feature of affected teeth were also examined. RESULTS: Dens invaginatus was observed in 85 of 1,004 subjects, with a prevalence of 8.47% and a tooth prevalence of 0.494%. Males presented a higher prevalence of DI than females (p = .011). Type I DI was the most commonly observed type of dens invaginatus, followed by type II and type III. The structure form of different types of DI was various. Overall 2.48% of the patients with type I DI, 5.88% of the patients with type II DI, 100% of the patients with type III DI had apical pathosis. Bilateral DI was found in 63.53% of the affected patients. CONCLUSIONS: This study indicates that DI was not rare, and clinicians should be aware of its existence. CBCT examination can provide an accurate representation of dental anatomy and should be incorporated into early diagnosis and treatment planning for teeth with DI.

Association between developmental dental anomalies, early childhood caries and oral hygiene status of 3-5-year-old children in Ile-Ife, Nigeria.

BACKGROUND: To determine the association between developmental dental anomalies (DDA), early childhood caries (ECC) and oral hygiene status of 3-5-year-old children resident in Ile-Ife, Nigeria. METHODS: This was a cross-sectional study. We analyzed data for 3-5-year-olds extracted from the dataset of a household survey collected to determine the association between ECC and maternal psychosocial wellbeing in children 0-5-year-old. The outcome variables for the study were ECC and poor oral hygiene. The explanatory variable was the presence of developmental dental anomalies (supernumerary, supplemental, mesiodens, hypodontia, macrodontia, microdontia, peg-shaped lateral, dens evaginatus, dens invaginatus, talons cusp, fusion/germination, hypoplasia, hypomineralized second molar, fluorosis, amelogenesis imperfecta). The prevalence of each anomaly was determined. Poisson regression analysis was conducted to determine the association between presence of developmental dental anomalies, ECC and oral hygiene status. The model was adjusted for sex, age and socioeconomic status. RESULTS: Of the 918 children examined, 75 (8.2%) had developmental dental anomalies, 43 (4.7%) had ECC, and 38 (4.1%) had poor oral hygiene. The most prevalent developmental dental anomalies was enamel hypoplasia (3.9%). Of the 43 children with ECC, 6 (14.0%) had enamel hypoplasia and 3 (7.6%) had hypomineralized second primary molar. There was a significant association between ECC and enamel hypoplasia (p < 0.001) and a borderline association between ECC and hypomineralized second primary molars (p = 0.05). The proportion of children with poor oral hygiene (PR: 2.03; 95% CI: 0.91-4.56; p = 0.09) and ECC (PR: 2.02; 95% CI: 0.92-4.46; p = 0.08) who had developmental dental anomalies was twice that of children with good oral hygiene and without ECC respectively, although the differences did not reach statistical significance. CONCLUSIONS: Enamel hypoplasia and hypomineralized second primary molars are developmental dental anomalies associated with ECC. developmental dental anomalies also increases the probability of having poor oral hygiene in the population studied.

A retrospective comparative study of cone-beam computed tomography versus rendered panoramic images in identifying the presence, types, and characteristics of dens invaginatus in a Turkish population.

INTRODUCTION: This study assessed the presence, characteristics, and type of dens invaginatus (DI) by using cone-beam computed tomography (CBCT) and panoramic images rendered from CBCT images. In addition, the findings of the imaging techniques were compared. METHODS: We evaluated 300 CBCT images to determine the type of DI, the presence of an impacted tooth near the DI, and the presence of apical pathosis. The McNemar test was used to compare the prevalence of DI according to CBCT and panoramic images rendered from CBCT images. RESULTS: The presence of DI was lower on panoramic images rendered from CBCT images (3% of the patients) compared with on CBCT images (10.7% of the patients) (P < .001). According to the CBCT images, the distribution of teeth with DI was as follows: maxillary lateral incisors (75%), maxillary central incisors (6.8%), mandibular premolars (4.6%), mesiodens (9%), maxillary canines (2.3%), and mandibular canines (2.3%). Type I DI was the most commonly observed type of invaginatus (65.9%), followed by type II (29.5%) and type III (4.6%). All patients with type III DI and 25% of the patients with type II DI had apical pathosis at the time of referral, but periapical lesions were not observed in teeth with type I DI. In total, 13.6% of DI cases had impacted teeth. CONCLUSIONS: CBCT can be recommended as an effective diagnostic device for identifying DI because it provides an accurate representation of the external and internal dental anatomy.

Prevalence of dental anomalies on panoramic radiographs in a population of the state of Pará, Brazil.

INTRODUCTION: Dental anomalies (DAs) are the result of disorders that are able to modify the shape, number, size, and structure of teeth. This study aimed to evaluate the prevalence of DAs using panoramic radiographs in a population of the City of Belém, northern Brazil. MATERIALS AND METHODS: In this study, 487 panoramic radiographs were evaluated searching for DAs. Dental records were reviewed for diagnostic confirmation. DAs related to the shape, number, size, and structure of teeth were investigated. RESULTS: Our results showed a DA prevalence of 56.9%. The most prevalent DA was taurodontism, which was present in 27.19% of cases. Root dilaceration was the second most prevalent DA in adults, whereas hypodontia was the second most prevalent DA in children. A total of 13 DAs were found. CONCLUSIONS: Dental anomalies were present in over half of the sample, and most of them were related to the shape of the teeth. Although there was a high prevalence of shape-related DAs, these alterations are generally of lower severity, and most do not require specific treatment. However, in 19.25% of cases, DAs were found involving the number, size and structure of the teeth. These DAs should be diagnosed and treated early, avoiding thus more serious complications.

The prevalence, pattern and clinical presentation of developmental dental hard-tissue anomalies in children with primary and mix dentition from Ile-Ife, Nigeria.

BACKGROUND: The study of dental anomalies is important because it generates information that is important for both the anthropological and clinical management of patients. The objective of this study is to determine the prevalence and pattern of presentation of dental hard-tissue developmental anomalies in the mix dentition of children residing in Ile-Ife, a suburban region of Nigeria. METHODS: Information on age, sex and socioeconomic status was collected from 1,036 children aged four months to 12 years through a household survey. Clinical examination was conducted to assess the presence of dental anomalies. Associations between age, sex, socioeconomic status, prevalence, and pattern of presentation of the developmental hard-tissue dental anomalies were determined. RESULT: Two hundred and seventy six (26.6%) children had dental anomalies. Of these, 23.8% had one anomaly, 2.5% had two anomalies, and 0.3% had more than two anomalies. Of the children with anomalies, 49.3%were male, 50.7%were female, and 47.8%, 28.6% and 23.6% were children from low, middle and high socioeconomic classes, respectively. More anomalies were seen in permanent than primary dentition. Anomalies of tooth structure were most prevalent (16.1%); anomalies which affect tooth number were least prevalent (1.3%). Dens evaginatus, peg-shaped lateral, macrodontia, and talon cusp were more prevalent in the permanent dentition, and dens evaginatus peg-shaped lateral and macrodontia were more prevalent in the maxilla. There were significantly more macrodontia anomalies in males and in children of high socioeconomic status. CONCLUSION: This large survey of dental hard-tissue anomalies found in the primary dentition and mixed dentition of children in Nigeria provides anthropological and clinical data that may aid the detection and management of dental problems of children in Nigeria.

Dental anomalies associated with buccally- and palatally-impacted maxillary canines.

AIM: The aim of the present study was to determine the association of both buccally- and palatally-impacted canines with other dental anomalies. METHODS: This retrospective study was conducted on a population of 533 southern Chinese children and adolescents who had impacted maxillary canines that had been treated in the Paediatric Dentistry and Orthodontics Clinic, Prince Philip Dental Hospital, The University of Hong Kong, Hong Kong. Descriptions of the impacted canine and other associated anomalies were obtained from the case notes and radiographs. Clinical photographs and study casts were used, where available. RESULTS: A total of 253 (47.5%) patients with impacted maxillary canines were diagnosed with other dental anomalies. Microdontia was the most frequently-occurring anomaly reported in these patients, with the maxillary lateral incisor the most commonly affected tooth. Other odontogenic anomalies that were associated with both buccally- and palatally-impacted canines included hypodontia, supernumerary teeth, transposition of other teeth, enamel hypoplasia, other impacted teeth, and dens invaginatus. CONCLUSION: Both buccally- and palatally-impacted canines were found to be associated with other odontogenic anomalies.

Dens invaginatus in ancient Chinese teeth of 2,000 years ago.

Dens invaginatus (DI) is a developmental anomaly of teeth. Here we observed the characteristics of DI in 517 permanent teeth from 67 ancient Chinese people using micro-computed tomography (micro-CT) scanning techniques. The individuals were excavated from Shaanxi province of China and identified to be about 2,000 years old. Four DI categories are proposed to distinguish the different types of DI. The invaginated lingual fossa is classified into three classes. The overall prevalence of DI in 67 individuals was 31.34% (21 of 67). DI was found in 25 of 517 teeth (4.83%). All affected teeth were maxillary lateral incisors. The invaginated lingual fossa (Type I DI) occurred most frequently (84%), followed by radicular grooves (Type II; 16%), while Type III and Type IV were not found in the present study. Some of fossae correspond with radicular grooves (8 of 21; 3 located at mesial, 5 were distal). The bilateral incidence of DI was 19.05%. Comparing our results to those of a retrospective survey of DI from 1873 to present, we found a higher rate of DI in the excavated teeth of Chinese individuals 2,000 years ago. The use of the micro-CT technique and ethnic origin might have contributed to the higher incidence of DI.

A retrospective study of the prevalence and characteristics of dens invaginatus in a sample of the Turkish population

Objective: The purpose of this study was to assess the prevalence of dens invaginatus and to classify the types of dens invaginatus in a sample of the Turkish population. Study Design: A retrospective study was performed using periapical and panoramic radiographs of 5355 patients who presented to the Department of Oral Diagnosis and Radiology at the Ondokuz Mayýs University Dentistry Faculty between January 2009 and December 2010. Maxillary and mandibular anterior teeth were evaluated for the presence and characteristics of dens invaginatus. Statistical evaluation of the presence of dens invaginatus related to gender was performed by the Pearson chi-squared test. Results: Dens invaginatus was observed in 116 of 4556 subjects, with a frequency of 2.5%. There was only one periapical lesion in teeth with type I dens invaginatus, but 8.1% of patients with type II and 87.5% of patients with type III dens invaginatus had apical periodontitis at the time of referral. There were 116 (72%) females and 32 (27%) males with dens invaginatus. Conclusion: This data represents the only study carried out in a large population in Turkey, and no dens invaginatus was found in mandibular teeth. The most commonly observed type of dens invaginatus was type I (69.8%) (AU)

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A retrospective study of the prevalence and characteristics of dens invaginatus in a sample of the Turkish population.

OBJECTIVE: The purpose of this study was to assess the prevalence of dens invaginatus and to classify the types of dens invaginatus in a sample of the Turkish population. STUDY DESIGN: A retrospective study was performed using periapical and panoramic radiographs of 5355 patients who presented to the Department of Oral Diagnosis and Radiology at the Ondokuz Mayis University Dentistry Faculty between January 2009 and December 2010. Maxillary and mandibular anterior teeth were evaluated for the presence and characteristics of dens invaginatus. Statistical evaluation of the presence of dens invaginatus related to gender was performed by the Pearson chi-squared test. RESULTS: Dens invaginatus was observed in 116 of 4556 subjects, with a frequency of 2.5%. There was only one periapical lesion in teeth with type I dens invaginatus, but 8.1% of patients with type II and 87.5% of patients with type III dens invaginatus had apical periodontitis at the time of referral. There were 116 (72%) females and 32 (27%) males with dens invaginatus. CONCLUSION: This data represents the only study carried out in a large population in Turkey, and no dens invaginatus was found in mandibular teeth. The most commonly observed type of dens invaginatus was type I (69.8%).

Prevalence and distribution of selected developmental dental anomalies in an Indian population.

The purpose of this study was to determine the prevalence of developmental dental anomalies in an Indian population and to statistically analyze the distribution of these anomalies. The study was based on clinical examination, evaluation of dental casts, and panoramic radiographs of 1123 Indian subjects (572 males, 551 females), who visited the outpatient clinic at Government Dental College, Indore between November 2009 and September 2010, after obtaining their informed consent. These patients were examined for the following developmental dental anomalies: shape anomalies (microdontia, talon cusp, dens evaginatus, fusion, taurodontism), number anomalies (hypodontia, oligodontia, anodontia), structural anomalies (amelogenesis imperfecta, dentinogenesis imperfecta) and positional anomalies (ectopic eruption, rotation, impaction). The percentages of these anomalies were assessed for the whole group and compared using statistical analysis. Among the 1123 subjects, a total of 385 individuals (34.28%) presented with the selected developmental dental anomalies. The distribution by sex was 197 males (34.44%), and 188 females (34.06%). Out of the total 1123 individuals, 351 (31.26%) exhibited at least one anomaly, 28 (2.49 %) showed two anomalies and 6 (0.53%) displayed more than two anomalies. P values indicated that the dental anomalies were statistically independent of sex. On intergroup comparison, positional anomalies were significantly most prevalent (P < 0.05) in the Indian population. The most common developmental dental anomaly was rotation (10.24%), followed by ectopic eruption (7.93%). The next common group was number anomalies. The most common number anomaly was hypodontia (4.19%), which had a higher frequency than hyperdontia (2.40%). Analyzing the next prevalent group of shape anomalies, microdontia (2.58%) was found to be the most common, followed by taurodontism (2.49%), dens evaginatus (2.40%) and talon cusp (0.97%). Dentinogenesis imperfecta (0.09%) was the rarest, followed by amelogenesis imperfecta (0.27%) and fusion (0.27%).

Assessment of the prevalence and characteristics of dens invaginatus in a sample of Turkish Anatolian population

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Assessment of the prevalence and characteristics of dens invaginatus in a sample of Turkish Anatolian population.

OBJECTIVE: The objective of this study was to assess the prevalence and characteristics of dens invaginatus in anterior teeth and to classify the type of dens invaginatus in a sample of Turkish Anatolian population. STUDY DESIGN: A retrospective study was performed using full-mouth periapical and panoramic radiographs of 1012 patients. Maxillary and mandibular anterior teeth were evaluated for the presence and characteristics of dens invaginatus. Statistical evaluation of the presence of dens invaginatus related to gender was performed by the Pearson chi-squared test. RESULTS: Dens invaginatus was observed in 13 out of 1012 subjects and in only maxillary lateral incisors. There were no periapical lesions in teeth with types I and II, whereas both of the subjects with type III had apical periodontitis at the time of referral. Males and females were equally affected by dens invaginatus (P=0.98). CONCLUSION: The anomaly was detected in only maxillary lateral incisors with no gender difference and the most commonly observed type of dens invaginatus was type I (81.25%).

[Dens invaginatus. Review of the literature and diagnostic and therapeutic guidelines]. / Dens invaginatus. Literaturübersicht und Leitlinien zur Diagnostik und Therapie.

Dens invaginatus is a clinically relevant malformation of teeth resulting from an infolding of enamel and dentine into the dental structure during tooth formation, hence the former denomination "dens in dente". The dens invaginatus shows multiple morphological variations of crown and root formation. This frequently leads to caries, pulpal and periodontal involvement with necrosis and loss of attachment. Therefore, early diagnosis and prevention are of utmost importance. Due to the complexity of the malformation, treatment options in former days were limited. This article presents a profound review of the literature regarding etiology, epidemiology and histology. It discusses clinical appearance and diagnosis and it provides guidelines for decision-making and treatment of invaginated teeth.

The prevalence of anterior teeth with dens invaginatus in the western Mediterranean region of Turkey.

AIM: To assess the prevalence and type of dens invaginatus in anterior teeth of a selected population and to report associated dental complications. METHODOLOGY: The records of patients examined in the Department of Paedodontics, Faculty of Dentistry, Süleyman Demirel University, Isparta, Turkey between 1999 and 2006 were screened and a total of 2477 patients who had complete records with satisfactory radiographs were selected. The type of dens invaginatus and the presence of apical pathosis was determined from radiographs. Other dental abnormalities, syndromes and systemic diseases were noted. Variations in crown shape were also recorded. RESULTS: Dens invaginatus was detected in 300 out of 2477 patients, with a prevalence of 12%; 82% of affected patients had dens invaginatus bilaterally. Maxillary lateral incisors were the most affected teeth. The majority of the teeth had normal crown morphology (95%). The most commonly seen type of dens invaginatus was type I (94%). Overall 33% of the patients with type III dens invaginatus and 4% of the patients with type II dens invaginatus had apical pathosis. No associations with other systemic diseases and syndromes and some limited association with hypodontia and dens evaginatus were detected. CONCLUSION: A careful oral examination, radiographs, a suitable treatment plan and follow-up programme are crucial for early diagnosis and treatment for teeth with dens invaginatus.

Prevalence of dental anomalies in various malocclusions.

INTRODUCTION: The purpose of this study was to evaluate the prevalence of dental anomalies in different orthodontic malocclusions. METHODS: Based on pretreatment diagnostic records, 900 orthodontic patients were classified as Class I (n = 358), Class II (n = 325), Class II Division 2 (n = 51), or Class III (n = 166). The occurrence rates of each dental anomaly were calculated as percentages of the total sample. Differences in incidence rates of each dental anomaly by sex and malocclusion were analyzed by using chi-square, Fisher exact, and z tests. The Mann-Whitney U test was used to determine whether there were significant differences in the occurrence of dental anomalies by age. RESULTS: It was found that 40.3% of patients (n = 363) had at least 1 dental anomaly. Agenesis was the most common (21.6%), followed by dens evaginatus (6.2%), invaginatus (5.0%), pulp stones (4.2%), and impaction (2.9%). No statistically significant correlations were found between dental anomaly and type of malocclusion, with the exception of impaction and short or blunt roots (P <0.01 and P <0.05, respectively). The Mann-Whitney U test indicated no significant difference in dental anomalies by age. CONCLUSIONS: A remarkably high rate of dental anomalies was recorded in orthodontic patients; therefore, orthodontists should carefully examine pretreatment records for dental anomalies to include their management in the treatment planning.

Tratamiento conservador de un diente invaginado tipo II: Informe de un caso / No disponible

El diente invaginado es una malformación de desarrollo caracterizada por la formación de un pliegue anormal del órgano del esmalte que se invagina hacia la papila dental antes de que ocurra la mineralización del diente. Los dientes más afectados son los incisivos laterales superiores. La malformación muestra in importante rango de variaciones morfológicas y frecuentemente evoluciona hacia una necrosis pulpar. La terapia endodóncica puede presentar muchos inconvenientes debido a la complejidad anatómica de los conductos radiculares. El tratamiento de esta malformación puede incluir el tratamiento de endodóncico convencional, seguido por una restauración estética o protética o requerir de un tratamiento quirúrgico complementario (AU)

Dens Invaginatus is a developmental anomaly resulting from invagination of the crown before calcification has occurred. The most affected teeth are maxillary permanent lateral incisors. This anomaly present many morphologic variations and frequently is the cause of a necrotic pulp. Root canal treatment can be difficult because of the complex anatomy of the teeth with dens invaginatus. The treatment of this anomaly may include a conventional root canal treatment followed by a restauration like a crown. In some cases periapical surgery is necessary or even the extraction of the tooth to solve the problem (AU)

Impaction of permanent mandibular second molars in ethnic Chinese schoolchildren.

OBJECTIVE: To investigate the prevalence of impaction of permanent mandibular second molars and associated dental and radiographic characteristics of Chinese children in Hong Kong. MATERIALS AND METHODS: Dental and radiographic records of a group of Chinese schoolchildren were studied retrospectively. Cases of impaction of 1 or both permanent mandibular second molars were selected. Demographic data and dental and radiographic findings were recorded and analyzed. The angle of the impacted second molars was measured on panoramic radiographs. RESULTS: Among the 3,053 records reviewed, 32 cases of impaction of permanent mandibular second molars were identified and studied. Mesial impaction was found in all but 1 case. The angle of the mesially impacted teeth ranged from 13 degrees to 75 degrees . Mandibular crowding and the presence of third molars were common. Dens evaginatus, taurodontism and Class III malocclusions were significantly more prevalent in the study group than in the general population of Chinese children of similar age. CONCLUSIONS: The prevalence of impaction of permanent mandibular second molars in Chinese children was estimated to be 1%. Thorough and regular examination of the child"s developing dentition is recommended to diagnose dental impaction promptly.