Prevalence Of Agenesis Research Articles

Radiographic evaluation of the prevalence of dental anomalies of number

Objectives: This study aims to determine the prevalence of tooth agenesis and supernumerary teeth and characterize both anomalies in a Portuguese pediatric population. Methods: Clinical records of patients attending Pediatric Dentistry appointments in the Faculty of Dental Medicine of the University of Porto were consulted. Appointments from September 2020 to December 2021 were analyzed. For each patient, sex and age were recorded, along with any relevant data in their clinical history. Statistical analysis of the results was conducted using chi-square tests with a significance level of 0.05. The sample included 144 patients. Results: This study found a prevalence for tooth agenesis of 20.83% (11.81% excluding the third molars) and a prevalence for supernumerary teeth of 1.39%. The prevalence of agenesis was 26.1% for males and 16% for females. No association was established in this regard (p>0.05). The most affected teeth were the third molars, followed by the second premolars. The mandible had 52.63% of agenesis cases, but no association was found (p>0.05). Two cases of supernumerary teeth were found, both in male patients and in the second quadrant. No differences were inferred regarding sex (p>0.05). Conclusions: The results of this study contributed to the existing data regarding the prevalence of dental anomalies of number within a Portuguese population.

Third Molar Agenesis in Post-Medieval Chichester

Third molar agenesis is a dental anomaly that occurs in approximately 25% of people worldwide and results in the complete absence of one or more of the third molars in the dentition. A rise in the prevalence of congenitally absent third molars has been noted in modern populations, and it has been proposed as the final evolutionary step in the dental reduction of the human dentition. 
 Whilst much research has been conducted in modern cohorts, relatively little has been published on third molar agenesis in archaeological assemblages. A post-medieval assemblage from Chichester was visually and radiographically analysed to determine the prevalence of this anomaly. Third molars were measured to determine if there was an association between agenesis and size reduction. Prevalence of agenesis was found to be relatively high at 42.7% and 2 of 8 measurements were found to produce significant differences.
 Consequently, it can be said that high rates of third molar agenesis are not solely a modern phenomenon, as many prevalence rates in recent populations are lower. However, if we are to assess the significance of size differences in third molars of those with agenesis and those without, and to detect patterns within and between these groups, assemblages with larger sample sizes are needed. In order to better understand the trajectory and evolution of this anomaly, more archaeological assemblages must be examined.

English

BACKGROUND Palmaris longus (PL) tendon agenesis varies from 5 % to 30 % in different ethnic groups worldwide. Its agenesis is associated with decreased wrist grip, pinch grip, presence of cheek dimples, difference of prevalence of agenesis with gender and handedness and with flexor carpi superficialis tendon. Student and general population surveys done in previous studies shows the association between these variables. The purpose of this study was to find out the association between the presence of cheek dimples with absence of palmaris long tendon. METHODS We examined 1200 medical and allied health students (600 males, 600 females) aged 18 - 24 years to assess the incidence of palmaris longus absence and the presence of cheek and chin dimples. The presence or absence of palmaris longus was assessed by clinical inspection using standard tests. The effectiveness of these’ standard tests’ is also tested along with wrist strength and pinch strength. RESULTS 163 students had PL agenesis. One hundred and twenty-one subjects had unilateral absence of palmaris longus (13.5 %). The tendon was absent bilaterally in 42 subjects (3.5) 77 students had either unilateral or bilateral cheek dimples out of 163 PL agenesis. The Mishra’s test is found to be most effective for properly defining the PL at wrist. CONCLUSIONS Prevalence of absence of palmaris longus is around 13.5 %. Unilateral agenesis of PL is 10 %. Absence of palmaris longus has strong association to presence of cheek dimples. Up to 45 % of PL agenesis will show either unilateral or bilateral cheek dimples. Studies on cheek dimples, panniculus carnosus are very scanty in literature; more studies might reveal interesting correlation. The grip strength of the wrist is unaffected due to palmaris longus agenesis; however, the pinch grip of 4th finger with thumb appears to be certainly decreased. Mishra’s test proves to be the best in demonstrating the PL. A radiant smile displaying the cheek dimples, has 50 % possibility of absence of PL. KEYWORDS Palmaris Longus Agenesis, Cheek Dimples, Bifid Zygomaticus Major, Panniculus Carnosus, Chin Dimples

Panoramic Radiographic Assessment of Agenesis of Mandibular Third Molars: A Hospital Based Study in Eastern Nepal

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. 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. 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%). 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.

Agenesis of second premolar teeth - diagnostics and treatment

Agenesis of second premolar teeth represents a problem that dentists and orthodontists deal with on a daily basis, and which will occur with greater and greater prevalence due to a tendency for the number of teeth to decrease evolutionally. Besides being an obvious aesthetic defect, the absence of teeth may cause serious functional effects such as, for example, malocclusion. Depending on the author of a research study, agenesis prevalence rate is reported to amount to 0.3 – 36.5 per cent, which suggests that it is a problem that every orthodontist will, sooner or later, have to handle. Very delayed development of second premolars described in the literature may also cause serious problems. <b>Aim.</b> This article is an attempt to present the problem in its entirety. It will discuss patient diagnostics, treatment planning in cases where buds of second premolars are missing as well as common tooth anomalies in subjects from the sample under examination. <b>Material and methods.</b> Selected scientific articles from the years 1939-2015 have been reviewed. <b>Results and conclusions.</b> A clinician has at their disposal at least several tools allowing for separation of patients that can be found in a group being at risk of agenesis or late development of second premolar teeth. A clinician may refer to the chronological age, adjacent teeth development stage or certain phenotypic traits described. A diagnosis made correctly is the foundation of good treatment strategy, which has to take into account a large number of the abovementioned factors. The best choice in these days when full wide smiles are preferred seems to be to leave the deciduous tooth in place for as long as possible.

Impact of Hematopoietic Stem Cell Transplantation on Dental Development

To investigate dental development in patients treated with a hematopoietic stem cell transplantation (HSCT), 42 children and young adults who were under 12 years old at time of HSCT were examined for dental agenesis, microdontia, and root-to-crown ratio. Conditioning regimens were total body irradiation (TBI) based in 12 patients, busulfan based in 21 patients, and 9 patients had other chemotherapeutic agents. Sixteen patients were <3 years old, 9 patients were 3 to 6 years old, and 17 patients were 6 to 12 years old at HSCT. Prevalence of agenesis and microdontia of at least 1 permanent tooth were, respectively, 51.3% and 46.2% in the study population, and 76.3% had an aberrant root-to-crown ratio. All these results were highly different from the prevalence in the healthy population. Patients treated before the age of 3 years had more microdontia (76.9%) and agenesis (92.3%) compared with patients treated at an older age. In the subgroup of patients treated after 6 years, there was more microdontia when treated with busulfan (50%) compared with treatment with TBI (0%) (P = .044). Patients treated with HSCT had many disturbances in dental development. Age at HSCT and possibly also the conditioning regimen used had an effect on their type and prevalence. Dental follow-up should be incorporated in the multidisciplinary follow-up program of these patients.

Prevalence and associated factors for agenesis of corpus callosum in Emilia Romagna (1981–2015)

Agenesis and hypoplasia of the corpus callosum (ACC and HCC) are heterogeneous group with a large variation in published prevalence based on few population based studies. The aim of this work is to describe prevalence, associated factors and other malformations present in cases with either agenesis or hypoplasia of the corpus callosum, using a population-based database of all malformations diagnosed in Emilia-Romagna, Italy, (the Emilia-Romagna Registry on Congenital Malformations, IMER).This registry links and integrates hospital discharge records, birth certificates with cases reported by referral clinicians to identify all structural malformations diagnosed within one year of life regarding live birth, fetal death or termination of pregnancy due to fetal malformations (TOPFA). During the study period (1981–2015) the number of cases with ACC or HCC was 255, in a reference population of 1,023,784 live births, giving an overall prevalence of 2.49 per 10,000 (1.47 per 10,000 only live birth). After 1996, with the inclusion of TOPFA in IMER registry, the overall prevalence rate increase significantly from 1.42 to 3.03 cases per 10,000 birth (p-value<0.001). Prenatal diagnosis was made in 192 cases (75.3%), at a median gestational age of 20.7 [IQR: 19.71–22.71]. Termination of pregnancy occurred in 105 of the 255 cases (41,2%). Where a prenatal diagnosis was available, 55% of cases ended in TOPFA (105/192), with higher prevalence of cases associated to central nervous system malformations and multiple birth defects, and median gestational age at diagnosis significantly less than in live birth cases (20.3 vs 29 weeks). Agenesis/hypoplasia ratio was 5.7 (217/38). The most frequently associated malformations were musculoskeletal. Trisomies were the most frequent chromosomal anomalies, in particularly trisomy18 and 13 (respectively 9/32 and 4/32 cases). Our study showed an increased risk for male infants (RR of 1.68, RR 95% CI 1.19–2.37). No differences were detected analyzing maternal age and ethnicity, and the increased risk associated to preterm birth disappeared when compared with other malformed infants.This is one of the few population based studies dealing with prevalence of agenesis and hypoplasia of corpus callosum. Prevalence is still debated, but this study adds comprehensive data, in particular inclusion of TOPFA cases. Early prenatal diagnosis, not always possible, could be crucial for decision making regarding continuation of pregnancy.

Tooth agenesis code (TAC) in complete unilateral and bilateral cleft lip and palate patients.

The objective of this study is to characterize and compare tooth agenesis codes and their prevalence in a population of Spanish patients with unilateral cleft lip and palate (UCLP) and bilateral cleft lip and palate (BCLP), and to determine if the extent of the cleft (BCLP or UCLP) was associated with the number of absent teeth. This retrospective cross-sectional human study included 118 patients with complete BCLP (29) or UCLP (89) and permanent dentition from first molar to first molar. Congenitally missing teeth were identified on panoramic radiographs using the tooth agenesis code (TAC) to identify agenesis codes. Agenesis prevalence was 50.6 and 51.7% for UCLP and BCLP patients, respectively. The lateral upper incisor was the most frequently absent tooth, especially in the cleft quadrant. Numbers of absent teeth ranged from 1 to 6. This study represents a different approach from previous agenesis investigations in cleft patients. These Spanish patients showed a high number of ageneses, presenting nineteen different tooth agenesis codes. A total of five TACs were unique, in other words, observed in a single patient in the sample. No statistically significant relationship was found between the extent of the cleft and the number of absent teeth. The TAC system makes it possible to identify agenesis codes with simultaneous absence of teeth not detected in general prevalence studies.

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.

Patterns of Tooth Agenesis in Patients with Crouzon or Apert Syndrome

Dental agenesis is the most common anomaly of dental development and can be a component of a congenital syndrome. The purpose of this study was to evaluate the prevalence of agenesis and to describe patterns of tooth agenesis in patients with Crouzon or Apert syndrome compared with nonsyndromic controls. Longitudinal records of 67 patients with Crouzon syndrome (n = 39) or Apert syndrome (n = 28) from the Erasmus Medical Centre were examined. Syndromic patients were compared with patients in a nonsyndromic control group (n = 284). Prevalence of tooth agenesis in patients with Crouzon syndrome (35.9%) and patients with Apert syndrome (46.4%) was significantly higher than the prevalence in control subjects (27.5%) (P < .005). In all groups third molars were the most likely to be agenetic. Tooth agenesis excluding third molars was significantly higher in syndromic patients than in control subjects (P < .001). Bilateral agenesis of mandibular second premolars occurred significantly more often in patients with Crouzon and Apert syndrome than in control subjects (P < .001). Tooth agenesis is more prevalent in patients with Crouzon or Apert syndrome than in control subjects. Tooth agenesis and mandibular symmetrical patterns of second premolar agenesis are more prevalent in syndromic patients.

Etiology of congenital hypothyroidism in Isfahan: Does it different?

Background:Considering the higher prevalence of congenital hypothyroidism (CH) in Iran and the importance of determination of the etiology of CH for assessing appropriate treatment strategies, understanding the pathogenesis of CH and the implications of its inheritance and prognosis, the aim of this study was to determine the etiology of CH 7 years after initiation of the program in Isfahan province.Materials and Methods:In this cross-sectional study, children with a primary diagnosis of CH studied. They clinically examined and their medical files were reviewed by a Pediatric Endocrinologist. Considering screening and follow-up lab data and radiologic findings the etiology of CH was determined. Screening properties of different etiologies of CH was compared.Results:In this study, 437 patients with permanent CH (PCH) were studied. Etiology of PCH in 316 (72.3%) and 121 (27.7%) of cases was thyroid dyshormonogenesis and thyroid dysgenesis, respectively. Prevalence of agenesis, ectopia, hypoplasia and hemiagenesis in thyroid dysgenetic patients was 13.3%, 6.4%, 4.3% and 3.7% respectively. Mean of thyroid stimulating hormone in screening, recall and after discontinuing treatment at 3 years of age was significantly lower in dyshormonogenetic CH patients than dysgenetic ones(P < 0.01).Conclusion:Seven years of our experiences in CH screening program indicated that the etiology of CH in Isfahan, with a higher rate of CH, with a predominance of thyroid dyshormonogenesis is different from most of the studies world-wide and similar to other reports from Iran. The findings of the current study provide us baseline information for determination of CH pathogenesis in this region.

Prevalence of palmaris longus agenesis in a hospital in Iran.

The prevalence of the palmaris longus agenesis (PLA) has been variously reported to be from 1.5% to 64% in different ethnic groups. Lack of reliable information about the state of the PLA in Iran made us to design a study on the agenesis of the palmaris longus (PL) among a sample of Iranian population during 2009. One thousand participants were included in this descriptive study. Subjects were patients and personnel of a major orthopedic surgery center in Iran. The Schaeffer test was used to detect the presence or absence of the PL. An orthopedic resident conducted the test (observer reliability 98%). The prevalence of agenesis was determined in the sample and its actual prevalence was estimated for the whole population. The role of gender and handedness was also considered in the presence or absence of the PLA. The prevalence of the PLA was estimated to be 22.8%; 10.2% agenesis on the right side, 5.9% on the left side, and 6.7% bilateral PLA. The relationship between PLA and gender didn't appear to be significant. Among people with PLA 43% and among people without PLA 17% were left handed (P < 0.05, odds ratio [OR]: 3.7). The prevalence of the PLA in Iranians seems to be comparable with the average Caucasian values which is estimated to be 22.4%. Furthermore, significant relationship exists between the PLA and left hand dominance.

Agenesis of Third Molars in Orthodontic Patients attending Dhulikhel Hospital

Aims and objective: The aim of this descriptive study was to determine the prevalence of agenesis or congenitally missing third molars in orthodontic patients attending Dhulikhel Hospital.&#x0D; Materials &amp; Methods: A retrospective study of a total of 294 patients, of both genders ranging from 12 to 34 years of age who were orthodontically treated between August, 2010 to May 2012, were reviewed from the files of the Department of Orthodontics, Dhulikhel Hospital, Kathmandu University Hospital. The records included panoramic radiographs and study models of all patients with intra oral photographs at the beginning of treatment.&#x0D; Results: It shows that agenesis of one to four third molars was present in male group in 63 cases out of 94, i.e, 67.02% and in the female group in 85 cases out of 200, i.e. in 42.5%. In the group of male and female together, we found the agenesis of one to four third molars in 148 cases, which is 50.34 %.&#x0D; Conclusions: Data concerning the incidence of third molars agenesis belong to the essential characteristics of the dentition's status of the given population. Dental developmental anomalies can indicate the degree of genetic load of individuals and relatives. By analyzing the global term "agenesis of one to four third molars" it is possible to receive data, which are quite significant for the orthodontic treatment plan.

Agenesis and Malformation of Maxillary Lateral Incisors in Orthodontic Patients. A Study

Objective: The purpose of this study was to deter-mine the prevalence of agenesis and malformation of maxillary lateral incisors in orthodontic patients. Study design: Cross sectional study. Place and Duration of Study: Department of Ortho-dontics, Faculty of dentistry, the University of Lahore, Pakistan; from January 2007 to march 2010. Patients and Methods: The data (history sheets, dental casts and panoramic radiographs) of 230 pati-ents (36.5% males, 63.5% females; mean age: 16.4 years) were randomly selected from orthodontic pati-ent's record. Congenital absence, size and shape of maxillary lateral incisors was noted. Patients with cleft lip and palate, ectodermal dysplasia or having any syndrome were excluded from the study. Results: The prevalence of small size lateral incisors was 5.6%. The prevalence of peg lateral was 1.3% and agenesis of maxillary lateral incisors was found in 2.17% of the patients. Conclusion: The prevalence of small maxillary lateral incisors is high as compared to other lateral incisor anomalies. Key words: Prevalence, maxillary lateral incisors, malformation.

The Prevalence of Agenesis of Palmaris Longus Muscle amongst Students in Two Lagos-Based Medical Schools

El musculo palmar largo (PL), aunque de poco uso funcional en el miembro superior humano, asume gran importancia cuando se utiliza como un tendon donante para la transferencia o trasplante. El cirujano ha tomado conciencia que la incidencia en una poblacion es por tanto deseable. En el presente estudio, 500 estudiantes de medicina (242 hombres y 258 mujeres) de 16 a 40 anos, de la Facultad de Medicina de la Universidad de Lagos (Idi-Araba) y la Facultad de Medicina de la Universidad Estatal de Lagos (Ikeja) fueron examinados para evaluar la presencia o ausencia del tendon del PL, utilizando la prueba convencional (Schaffer's). La prevalencia y el patron de agenesia del PL fueron determinados para analizar diferencias estadisticas en la prevalencia o patron de agenesia del PL con respecto al lado del cuerpo o sexo. Se encontro una prevalencia de agenesia del PL de 12,6% (8% y 4,6% unilateral y bilateralmente). De los sujetos con agenesia unilateral, 20 (4%) eran en el lado izquierdo y 20 (4%) en el lado derecho. Las mujeres tuvieron una prevalencia de agenesia del tendon del PL (unilaterales y bilaterales combinadas) en 36 de 258 (13,95%), mientras que en los hombres esta prevalencia fue en 23 de 242 (9,5%). La prevalencia de agenesia del musculo PL en este estudio se encontro mucho mas alto que el promedio reportado para los negros (2-3%).

Dental anomalies in individuals with cleft lip and/or palate

Significant heterogeneity has previously been reported but with no consensus on the prevalence of dental anomalies in subjects with a cleft lip and palate (CLP), thus, the purpose of this study was to investigate the frequency of various dental anomalies in the upper dental arch in different cleft groups. Diagnostic records, i.e., panoramic, occlusal and periapical films, dental casts, and intra-oral photographs, of 122 subjects (mean age: 14 +/- 5 years; 67 males and 55 females) were grouped as either unilateral left cleft lip and palate (ULCLP), unilateral right cleft lip and palate (URCLP), bilateral cleft lip and palate (BCLP), or cleft palate (CP). Prevalence rates of 15 different dental anomalies were calculated for each group. Wilcoxon's test was used to determine if there was a statistically significant difference in the number of missing teeth between the right and left sides, in each cleft group. Overall, 96.7 percent of patients were found to have at least one dental anomaly. The most prevalent was agenesis in the anterior region on the cleft side (70.8-97.1 percent). There was a statistically significant difference in the prevalence of agenesis by cleft and non-cleft sides but only in the ULCLP group (P < 0.001). Significantly higher rates of impaction were observed in the anterior and premolar regions in the CLP groups (2.9-29.2 percent), with the highest rates in the anterior region on the cleft sides. A very high proportion of subjects were found to have at least one dental anomaly. Thus, the management of dental anomalies should be central to the treatment planning process of individuals with a cleft.

Clinical relevance of palmaris longus agenesis: Common anatomical aberration

Palmaris longus muscle, although of little functional use to the human upper limb, assumes great importance when used as a donor tendon for transfer or transplant. The variability in the prevalence of palmaris longus agenesis among various ethnic groups has been established, and the surgeon's awareness of the prevalence in a population or ethnic group is desirable. The prevalence of palmaris longus agenesis has, to the best of the authors' knowledge, not been reported in Indian patients. Five hundred Indian patients were examined for the presence or absence of palmaris longus tendon, using the conventional test for presence of palmaris longus. The prevalence and pattern of palmaris longus agenesis was analyzed statistically and any difference in prevalence or pattern of palmaris longus agenesis with regard to body side or sex was looked for. All statistical analysis was done using SPSS (version 12). chi2 test was used to analyze the association of agenesis with limb laterality and sex. The prevalence of palmaris longus agenesis was found to be 17.2% (8% bilateral and 9.2% unilateral). The prevalence of agenesis was significantly more common on the left side. Male subjects had a greater likelihood of unilateral agenesis, while female subjects were more likely to have bilateral agenesis. That prevalence of palmaris longus agenesis is race dependent is reaffirmed in the present study. Although the prevalence of palmaris longus agenesis in Indian patients was found to be much higher than the reported average prevalence in an Asian population, this tendon can still be counted on by surgeons treating Indian patients for use as a donor tendon, which will be present in a vast majority of Indian patients.

Prevalence of Ectopic Eruption, Impaction, Retention and Agenesis of the Permanent Second Molar

To elucidate the prevalence of ectopic eruption, impaction, and primary and secondary retention as well as agenesis of the permanent second molar (M2) among adolescents. After a sample size calculation, dental records, including radiographs, of 1543 patients (722 girls and 821 boys), from three clinics in the city of Malmoe, Sweden, were retrospectively analyzed. Series of annual records and radiographs were examined for all patients from 10 to 16 years of age and were carried out during 2004-2006. The prevalence of ectopic eruption, impaction, and primary and secondary retention as well as agenesis of M2s was registered in a standardized manner and according to preset definitions. In addition, the times of emergence of the M2s were recorded. The prevalence of ectopic eruption of M2 was 1.5%, the prevalence of primary retention was 0.6%, and the prevalence of impaction was 0.2%. This means that the overall prevalence of eruption disturbances was 2.3%. In addition, the prevalence of agenesis was 0.8%. The prevalence of ectopic eruption was significantly higher in the mandible. Those patients with eruption disturbances and agenesis of M2 showed significantly delayed eruption of their other M2s compared to the individuals without any eruption disturbances. The prevalence of eruption disturbances was higher than reported earlier, and, even if the disturbances do not occur frequently, it is important to develop an early diagnosis in order to start the treatment at the optimal time.

More women in Europe and Australia have dental agenesis than their counterparts in North America

Medline and Embase were searched, using the following keywords: "hypodontia", "oligodontia", "anodontia", "agenesis", and "prevalence or incidence". Reference lists from retrieved articles were also examined. For inclusion, an article had to satisfy the following criteria: presence of an English abstract; the sample was representative for the underlying general population; the diagnosis of dental agenesis was based on a radiographic examination; the report presented information on the ethnic background; and the report presented prevalence of agenesis except third molars. Data from Caucasian populations in North America, Australia and Europe were included in a meta-analysis. For the prevalence in African-American, Chinese and Arab groups, only indications could be reported because of a limited number of studies. Multiple-regression analysis was applied to evaluate the influence of chronological age, sample size, continent and year of publication. Statistical significance was established at P<0.05. The prevalence of agenesis per tooth type, affected patients and number of missing teeth per patient was calculated as far as reported in the papers. For the comparison of the prevalence for males and females, the relative risk (RR) was calculated. The search identified 141 articles, of which 31 met the inclusion criteria. Agenesis differs by continent and gender: the prevalence for both sexes was higher in Europe (males 4.6%; females 6.3%) and Australia (males 5.5%; females 7.6%) than for North-American Caucasians (males 3.2%; females 4.6%). In addition, the prevalence of dental agenesis in females was significantly higher than in males for all three continents, with an RR of 1.37 (95% CI, 1.28-1.45). The mandibular second premolar was the most affected tooth, followed by the maxillary lateral incisor and the maxillary second premolar. Unilateral occurrence of dental agenesis is more common than bilateral occurrence. Bilateral agenesis of maxillary lateral incisors is more common, however, than unilateral agenesis. In most patients, dental agenesis involved only one (48%) or two teeth (35%). The prevalence of dental agenesis in Europe and Australia is higher than in North America. The overall prevalence of agenesis in the maxilla is comparable with that in the mandible, but a marked difference was found between both jaws regarding tooth type. Absence of one or two permanent teeth is found in the majority of the subjects with dental agenesis.

A meta-analysis of the prevalence of dental agenesis of permanent teeth.

To gain more insight into the prevalence of dental agenesis. Data from Caucasian populations in North America, Australia and Europe were included in a meta-analysis. For the prevalence of African American, Chinese and Arab groups only indications could be reported because of a limited number of studies. Agenesis differs by continent and gender: the prevalence for both sexes was higher in Europe (males 4.6%; females 6.3%) and Australia (males 5.5%; females 7.6%) than for North American Caucasians (males 3.2%; females 4.6%). In addition, the prevalence of dental agenesis in females was 1.37 times higher than in males. The mandibular second premolar was the most affected tooth, followed by the maxillary lateral incisor and the maxillary second premolar. The occurrence of dental agenesis was divided into three main groups: common (P2(i) > I2(s) > P2(s)), less common (I1(i) > I2(i) & P1(s) > C(s) & M2(i)) and rare (M2(s) & M1(s) > C(i) > M1(i) & I1(s)). Unilateral occurrence of dental agenesis is more common than bilateral occurrence. However, bilateral agenesis of maxillary lateral incisors is more common than unilateral agenesis. The overall prevalence of agenesis in the maxilla is comparable with that in the mandible, but a marked difference was found between both jaws regarding tooth type. Absence of one or two permanent teeth is found in 83% of the subjects with dental agenesis. A practical application of the results of the meta-analysis is the estimation of dental treatment need.