The influence of impaction to the third molar mineralization in northwestern Chinese population

Age estimation by third molar mineralization has been developed for a period of time. Recent studies showed that impaction status has an influence on the rate of the third molar mineralization in Europids and male Black African populations. In this regard, the present study was conducted to determine whether the impaction status could delay the chronological process of third molar mineralization in northwestern Chinese population too. A total of 3,512 digital orthopantomograms of 1,255 male and 2,257 female northwestern Chinese subjects aged from 11 to 26 years were assessed based on the formation stages described by Demirjian et al. with two modifications. Mineralization stage and impaction status were determined for all third molars. Statistical measures were calculated at stages C–H in the male and female gender for both impacted and non-impacted third molars. It was ascertained that the mean ages with impacted third molars at stages C–H were 0.02–1.42 years higher in males and 0.04–1.52 years higher in females than those with non-impacted third molars, but statistical differences were only found at stages C, D, and E in males and stages D and E in females. The probabilities of being under 14, 16, or 18 years of age with non-impacted third molars were all higher than those with impacted third molars. The results prove that impacted third molars show significant slower mineralization than non-impacted ones at stages D and E in both males and females of northwestern Chinese population. It is recommended to consider the influence of impaction on the rate of third molar mineralization for dental age estimation.     

105名飞行员第三磨牙萌出及阻生状况调查分析

目的 调查我军飞行员第3磨牙萌出、阻生情况以及引起的相关临床症状情况,为飞行员口腔健康保健提出建议. 方法 采用问卷调查、临床检查、全口曲面断层检查的方式,调查105名飞行员的第3磨牙及其引起的临床症状情况,收集主观感受,并用统计学软件SPSS11.0对所有数据进行统计学分析. 结果 共检出第3磨牙302颗,正常萌出68颗,阻生234颗;其中上颌正常萌出49颗,下颌正常萌出19颗;下颌阻生162颗,上颌阻生72颗,两者比较差异有统计学意义(x2=37.41,P＜0.01).视诊及X线检查均检出正常萌出第3磨牙68颗;视诊检出阻生第3磨牙190颗,X线检查检出234颗,两种检查方法检出结果差异有统计学意义(x2=42.02,P=0.00).受检人群出现第3磨牙肿痛症状或张口受限者88人,占83.8％.只有7例接受拔除第3磨牙根治疗法,调查显示,飞行员还存有拔牙恐惧心理. 结论 飞行员第3磨牙的发生率高,且多数出现临床症状,提示我们必须对其提高认识,防止并发症影响飞行安全.建议采用X线检查飞行员第3磨牙致病情况,对可能引起症状的第3磨牙可以行早期预防性拔除.建议开展系统的、更广范围的飞行人员口腔健康调查.     

Possibilty of the lower third molar eruption--radiographic analysis

BACKGROUND/AIM: To assess the possibility of the eruption of the lower third molar on the basis of the measured parameters: retromolar space, mesiodistal crown width of a molar and the third molar angulation. METHODS: The investigation included 104 patients both sexes (43 boys, and 61 girls), 16 to 25 years old (mean age, 18 years). It was performed using the orthopanthomographic radiographs analysis of those patients. Each radiograph was covered by tracing paper, and the contoures of the following anatomic details were drawn: a) the crown and root contours of third molars, upper and lower central incisors, distal molars in occlusion, anterior edge of ramus mandible, b) lines: 1. the occlusal plane, 2. the line of retromolar space, 3. the mesiodistal crown width of third molar, 4. the axial shaft of the third molar and the distal angle between occlusal plane and the axial shaft of the third molar. The values were measured with an orthodontic caliper: the diameter of retromolar space, diameter of mesiodistal width, the value of distal angle between occlusal plane and axial shaft of molar. RESULTS: A favourable angulation of the lower third molar (more than 60 degrees) was found in, boys (left 27.90%, right 32.55%), girls (left 39.34%, right 37.77%). A favourable relationship between the diameters of mesiodistal width of the third molar and retromolar space was found in, boys, (left 13.59%, right 16.27%), girls, (left 8.19%, right 14.75%). A favourable relationship between the diameters of mesiodistal width of the third molar and the retromolar space and the angulation was found in boys, (left 9.30%, right 11.62%), girls, (left 6.56%, right 9.83%). CONCLUSION: There was not any statistically significant difference found between the relation of the retromolar value, third molar mesiodistal diameter, or of the third molar angulation to the left and the right side nor of their mutual relations in comparing boys and girls. A favourable prognosis was found in 9.33% of the patients.     

Studies on the chronology of third molar mineralization in a Japanese population

In Germany, a sharp increase in forensic age estimations of living individuals has been observed in recent years. With regard to the relevant age group, radiologic assessment of the mineralization stage of the third molars is of particular importance. Still, the influence of ethnicity on the pace of mineralization has been insufficiently analyzed. A total of 1615 orthopantomograms of 929 female and 686 male Japanese subjects aged between 12 and 30 years was examined. The mineralization stages of third molars were evaluated on the basis of Demirjian's stages modified in accordance with Mincer's model. For the individual mineralization stages, the study presents the means and standard deviations for the genders separately. No statistically significant differences in the chronology of third molar mineralization between maxilla and mandible and between sides were observed. A comparison between genders largely did not render significant differences either. Apart from forensic age determination in living subjects, the presented reference data can also be used for age estimations of unidentified corpses and skeletons.     

Evaluation of chronological age based on third molar development in the Spanish population

A cross-sectional study was carried out to assess chronological age estimation based on the stages of third lower molar development, following the eight stages (A–H) method of Demirjian et al. The final sample consisted of 1,054 orthopantomograms from Spanish individuals of known chronological age (range 14–21 years) and gender (462 males and 592 females). Results showed a stronger correlation for males (r²=0.54) than for females (r²=0.45). Root formation occurred earlier in males than females, in stages 5, 6 and 7. The mean difference between chronological and estimated age was –0.10 years (±1.23 SD) for left third molar, and –0.07 years (±1.22 SD) for right third molar, with slight variations regarding sex. Comparative tables are provided regarding medicolegal questions concerning age 18 prediction in the Spanish population, showing that legal age is reached in stage 7 (G) by women and in stage 8 (H) by men. No differences have been observed between sides (p<0.0001). Differences were observed between Spaniards and other previously studied populations. Third molar maturity takes place earlier in the Spanish than French-Canadian, Scandinavian, American, German, Japanese and South African populations and is more similar to US Hispanics in root development.     

Studies on the chronology of third molar mineralization in First Nations people of Canada

Forensic age estimation of living subjects has become increasingly important in recent years. One main criterion for dental age estimation in the relevant age group is the evaluation of third molar mineralization. In the present study, we determined the stages of third molar mineralization in 347 female and 258 male First Nations people of Canada aged 11 to 29 years based on radiological evidence from 605 conventional orthopantomograms. The results presented here provide useful data on the mineralization stages of third molars that can be used for forensic estimation of the minimum and most probable ages including the range of scatter of investigated persons.     

降低智齿冠周炎在新兵中发病率的探讨

智齿冠周炎是口腔科的常见病、多发病,主要发生在18～30岁智齿萌出期的青年人。部队因青年人相对集中,是阻生牙和冠周炎的高发人群。全军“八五”期间口腔调查显示,在某驻地部队1084名士兵中,第三磨牙阻生率占18．1％,冠周炎发病率93．9％。治疗该病需要多次就诊,疗程较长,对于高度集中统一的部队官兵,就诊十分不便。     

The chronological age estimation of third molar mineralization of Han population in southwestern China

The purpose of the study was to estimate the chronology of third molar mineralization in Han population of southwestern China and find its unique characteristics so that it would provide a reference in several legal cases like forensic age estimation. The study used Demirjian's staging method to study 2192 orthopantomograms of 984 male and 1208 female subjects aged between 8 and 25 years. The statistical data was analyzed by Student's t test and ANOVA.The conclusions of the study are: (1) The chronological mineralization age of third molars of Han population in Southwestern China is similar to the Turkish and the Japanese, was earlier than the Austrian and Han of South China, but later than the Spanish. (2) The mineralization timing of the third molars between two sides in maxilla or mandible has no significant differences in the same gender group. (3) There is no significant difference in mineralization of third molars between male and female, except for tooth 48 in Demirjian's stage E. (4) The mineralization of third molar in maxilla is earlier than mandible.     

Chronological course of third molar eruption in a Portuguese population

Forensic age determination has become increasingly important over the past few years. Dental age estimation is frequently used as a part of this process due to the technique simplicity and reliability. This process is done taking into account pre-established values that, often, concern the population of the undocumented person. In this manner, population parameters are needed. In this paper, the authors present data concerning the third molar eruption in a Portuguese population: The minimum age for alveolar emergence of third molars ranged from 6.6 to 11.3 in females and 7.4 to 8.3 in males, for gingival emergence was 11.1 to 15.1 for females and 8.3 to 14.4 in males and for complete emergence was 15.9 to 19.4 in females and 13.4 for males. Complete emergence was found to be a useful marker for diagnosing age inferior 16 years, both in males and females, with 99.2% and 99.3% of correct predictions, respectively. These findings point out that it is possible to estimate the age of investigated persons based on alveolar, gingival and complete emergence of the third molars in the occlusal plane.     

Chronological age estimation based on third molar development in a Portuguese population

Third molar development was assessed using a sample of 1,131 orthopantomograms from a Portuguese population. The methodology applied was the eight stages (A–H) method described by Demirjian et al. The final sample was made of 739 orthopantomograms, 387 (52.5%) of which belonging to females; age ranged between 6.1 and 22.5 years old (mean age = 14.49, S.D. = 4.37). For each developmental stage, mean age, standard deviation, and minimal and maximal age was assessed; evaluation of the rate formation of each tooth, according to sex, was calculated and data distribution expressed in percentiles for each stage; the probability of an individual being 16 was also evaluated. The relationship between tooth development and chronological age had a statistical significance for all teeth and both sexes (p < 0.0001). The data described may provide reference for forensic application and agree with the thesis that each population need specific data.     

Comparative study on the chronology of third molar mineralization in a Japanese and a German population

In Germany, a sharp increase in forensic age estimations of living persons has been observed in recent years. German law defines four legally relevant age limits: 14, 16, 18 and 21 years. In these age groups, radiographic assessment of the mineralization status of third molars is of particular importance. So far, the influence of ethnicity on the mineralization rate has been insufficiently analyzed. A total of 3031 orthopantomograms of 1597 Japanese and 1434 Germans aged between 12 and 26 years were examined. The mineralization status of third molars was evaluated on the basis of the classification proposed by Demirjian. For the individual mineralization stages, the study presents the mean values and standard deviations (SD) separately for both populations and sexes. The majority of probands from both the Japanese and the German population achieved the C stage and the late G and H stages of third molar development at similar ages. Significant differences between Japanese and Germans were observed, however, with regard to the D, E and F stages defined by Demirjian. Japanese men and women achieved the D, E and F stages approximately 2-3 years later than German men and women. In addition to forensic age determination in living persons, the presented reference data can also be used for age estimations of unidentified deceased persons and skeletons.     

Sex discrimination from the glenoid cavity in black South Africans: morphometric analysis of digital photographs

Given that skeletal material recovered from medicolegal contexts is often incomplete or damaged, forensic anthropologists need to have a variety of techniques at their disposal in order to correctly determine the sex of unidentified human remains. The purpose of the present study, therefore, was to produce practical standards for discriminating the sex of black South Africans using measurements of the glenoid cavity of the scapula. Standardized digital photographs of the left glenoid fossa were taken for 60 males and 60 females drawn from the Pretoria Bone Collection. An image analysis software program was then used to collect height, breadth, area, and perimeter data from each digital photograph. All four dimensions of the glenoid cavity were highly sexually dimorphic in this population group (p < 0.0001). Univariate logistic regression analysis yielded overall sex prediction success rates ranging from 88.3% for area of the glenoid fossa to 85.8% for glenoid fossa breadth. Multivariate procedures did not provide increased accuracy over those using only a single variable. Classification sex biases were below 5.0% for all equations. These results demonstrate that the analysis of glenoid cavity size provides a highly accurate method for discriminating the sex of black South Africans.     

Effect of explaining radiographic information to the patient before third molar surgery

Objectives

The aim of this study was to compare patient satisfaction with the pre-operative information before and after explaining the radiograph and to compare patient satisfaction with the radiographic information when based on a digital or a conventional image, as well as on extraoral or intraoral images.

Methods

263 patients (with 301 mandibular third molars) were given pre-operative information by one of two trained scholar students before removal of the third molar. The course of the surgery and possible post-operative complications and risks were explained to the patient. The patients rated their satisfaction with the information on a 100 mm visual analogue scale (VAS). The radiograph was displayed and the radiographic information was explained to the patient, with emphasis on tooth-specific risk factors. The patients again rated their satisfaction on a VAS.

Results

There was no significant difference in patient satisfaction score before (mean VAS = 92.5 mm) and after (mean VAS = 91.7 mm) the radiographic information was explained (P = 0.15). No difference in satisfaction was found between patients who were shown either digital or conventional images or between patients who were shown either extraoral or intraoral images (P > 0.5).

Conclusions

No additional patient satisfaction was obtained by showing and explaining the radiograph to the patient before lower third molar surgery. If the dentist still wishes to show the patient the radiograph, the type of image seems not to be important.     

Chronological age estimation of third molar mineralization of Han in southern China

In order to study the chronology of age of third molar mineralization of Han in southern China, Demirjian staging method was used to determine the stage of four third molars (18, 28, 38, 48) mineralization in 3,100 Han in southern China aged 4.1–26.9 years based on radiological evidence from digital orthopantomograms. The mean age of the 3,100 patients was 15.96 ± 4.73 years, including 1,200 male (mean age, 15.32 ± 4.62) and 1,900 female (mean age, 16.35 ± 4.76). Results show that there was no significant difference in mineralization between 18 and 28 and 38 and 48 of male or female. However, significant difference was observed between 28 and 38 of female at stage C; 28 was 0.25 years earlier than 38. In male, at stage G, 38 was 0.61 years earlier than 28, and 48 was 0.62 years earlier than 18. At stages D, E, F, G, and H, male 48 was 0.34, 0.66, 0.72, 1.34, and 0.76 years earlier than that of female, respectively. At stages A, D, E, F, G, and H, male 38 was 0.73, 0.26, 0.56, 0.91, 1.29, and 0.70 years earlier than that of female, respectively. At stages B, E, F, G, and H, the mineralization mean age of male 18 was 0.54, 0.50, 0.76, 0.92, and 0.58 years earlier than that of female, respectively. At stages E, F, G, and H, the mineralization mean age of male 28 was 0.51, 0.76, 0.92, and 0.49 years earlier than that of female, respectively. After reviewing the literature, the chronological mineralization age of 48, at stages D to G, of Han in southern China was 1 to 4.6 years earlier than that of Japanese and 1 to 3 years earlier than that of German. The mean age at stage H of 48 of Han in southern China was similar to Turkish, Black African, Japanese, and German, but was later than Spanish. Finally, the conclusions are: (1) in the same gender group of Han in southern China, the mineralization ages between two sides in upper or lower jaw are very similar, and (2) the chronology mean age and complete time of third molar mineralization of male were earlier than that of female.     

Unerupted lower third molar as a cause of acute infection in soldiers

BACKGROUND/AIM: To record the frequency of infections as complications accompanying the unerupted lower third molars and to determine if there was a significant level of the relationship between the frequency and the severity of infections and the age of patients. METHODS: This study included 100 soldiers of the Army of Serbia & Montenegro, with the unerupted third molars, of male sex, 18 to 25 years old, who were receiving clinical treatment. RESULTS: In 73% of the patients the infection was caused with the unerupted lower third molars. The highest frequency of infection was observed in the group of 20-23 years of age (75.3%). Mild infection occurred in 49 (67.1%) of the patients. CONCLUSION: The frequency of infection was significantly higher in the older patients. Because of the high frequency of the infection recorded, the unerupted lower third molars should be surgically removed before the age of 20.