Validity of demirjian and nolla methods for dental age estimation for Northeastern Turkish children aged 5–16 years old

Objective: To evaluate the applicability of Demirjian and Nolla methods for northeastern Turkish population. Material and Method: A retrospective study was performed on panoramic radiographs of 673 subjects aged 5–15.9 years. The mean dental age (DA) according to the Demirjian and Nolla methods were compared to the mean chronological age (CA). Results: The mean CA of the study sample was 10.37±2.90 and 10.03±2.81 years for females and males, respectively. Using the Demirjian method, the mean estimated DA was 11.26±3.02 years for females and 10.87±2.96 years for males. For Nolla method, the mean estimated DA was 9.80±3.41 and 9.53±3.14 years for females and males, respectively. The mean differences between the CA and DA according to the Demirjian and Nolla methods were 0.86 and -0.54 years for total study sample. Conclusion: Nolla method was found to be a more accurate method for estimating DA in northeastern Turkish population. Key words:Dental age, demirjian method, nolla method, chronological age.     

Validity of demirjian and nolla methods for dental age estimation for Northeastern Turkish children aged 5-16 years old

Objective: To evaluate the applicability of Demirjian and Nolla methods for northeastern Turkish population. Material and Method: A retrospective study was performed on panoramic radiographs of 673 subjects aged 5-15.9 years. The mean dental age (DA) according to the Demirjian and Nolla methods were compared to the mean chronological age (CA). Results: The mean CA of the study sample was 10.37±2.90 and 10.03±2.81 years for females and males, respectively. Using the Demirjian method, the mean estimated DA was 11.26±3.02 years for females and 10.87±2.96 years for males. For Nolla method, the mean estimated DA was 9.80±3.41 and 9.53±3.14 years for females and males, respectively. The mean differences between the CA and DA according to the Demirjian and Nolla methods were 0.86 and -0.54 years for total study sample. Conclusion: Nolla method was found to be a more accurate method for estimating DA in northeastern Turkish population.     

Treatment effects produced by the Twin-block appliance vs the Forsus Fatigue Resistant Device in growing Class II patients

Objective:To compare the dentoskeletal changes produced by the Twin-block appliance (TB) followed by fixed appliances vs the Forsus Fatigue Resistant Device (FRD) in combination with fixed appliances in growing patients having Class II division 1 malocclusion.Materials and Methods:Twenty-eight Class II patients (19 females and 9 males; mean age, 12.4 years) treated consecutively with the TB followed by fixed appliances were compared with a group of 36 patients (16 females and 20 males; mean age, 12.3 years) treated consecutively with the FRD in combination with fixed appliances and with a sample of 27 subjects having untreated Class II malocclusion (13 females and 14 males; mean age, 12.2 years). Mean observation interval was 2.3 years in all groups. Cephalometric changes were compared among the three groups by means of ANOVA and Tukey''s post hoc tests.Results:The FRD produced a significant restraint of the maxilla compared with the TB and control samples (SNA, −1.1° and −1.8°, respectively). The TB sample exhibited significantly greater mandibular advancement and greater increments in total mandibular length than either the FRD or control groups (SNB, 1.9° and 1.5°, respectively; and Co-Gn, 2.0 mm and 3.4 mm, respectively). The FRD produced a significantly greater amount of proclination of the mandibular incisors than what occurred with the TB or the control samples (2.9° and 5.6°, respectively).Conclusion:The TB appliance produced greater skeletal effects in terms of mandibular advancement and growth stimulation while the Forsus caused significant proclination of the mandibular incisors.     

Dental age table for a sample of Pakistani children

The aim of this study was to evaluate the applicability of Demirjian's dental age assessment table in a sample of Southern Pakistani population and, if not applicable, to formulate a separate dental age table for Pakistani males and females. The study was conducted on the dental pantomographs of a sample size of 882 subjects (427 males and 455 females) ranging in age from 7 to 14 years. A paired t-test was used to assess any difference between chronological age and dental age assessed according to Demirjian's method. Logit function was used to make the relationship between dental maturity and chronological age and linear regression analysis with the equation X = [Ln {y/100 - y} - a]/b was used to generate dental age tables for Pakistani males and females. Dental age assessed according to Demirjian's method for this male sample was over-predicted in the 7 year and 11-15 year age group (P < 0.05). In the female sample, there was an over-prediction in all the age groups (P < 0.05). Statistically significant differences were found in chronological and dental age assessed by Demirjian's method for Pakistani males and females and thus, a new table was generated to convert dental maturity calculated according to Demirjian's method into dental age for the population.     

颈椎骨龄与牙龄推断上海地区儿童年龄的准确性比较

目的 ：评估并比较Willems牙龄推断法和上海地区特异性颈椎骨龄回归公式2种方法在推测上海地区儿童实足年龄上的适用性及准确性。方法：选取符合纳入标准的上海地区8～15岁儿童的全景片和头颅侧位片640张（男160名,女160名,全景片和头颅侧位片各320张）,分别运用Willems法和颈椎骨龄回归公式评估得到牙龄和颈椎骨龄。采用SPSS 25.0软件包中的配对t检验或Wilcoxon符号秩检验,评估实足年龄与推断年龄之间的差异;通过比较2种方法的标准差、平均绝对误差、可接受误差内的正确判断率,对2种方法的准确性进行评价。结果：相比实足年龄,男性牙龄平均低估（0.75±1.03）岁,女性平均低估（1.05±1.18）岁;男性颈椎骨龄平均低估（0.78±1.40）岁,女性平均低估（0.53±1.31）岁。Willems牙龄推断法的总平均绝对误差为1.15岁,上海地区颈椎骨龄回归公式的总平均绝对误差为1.20岁。临床可接受误差在±0.5岁内的正确判断率Willems法和颈椎骨龄回归公式分别为26.25%和27.19%。结论：相比上海地区特异性颈椎骨龄回归公式,Willems法在推断上海地区8...     

Prevalence of dental disease amongst 5-6 and 12-13 year old school children of Puttur municipality, Karnataka State-India

A survey was conducted among 5-6 and 12-13 years old school children of Puttur municipality, Karnataka State, India, to assess the prevalence of dental caries, malocclusion and dental calculus. A sample size of 200 subjects was taken for each age group and cluster-sampling method was used to select those schools which were to be included in the sample frame. Data collection was done using the Basic Oral Health Survey (WHO) form. The deciduous dentition alone was considered for 5-6 year old subjects while the permanent dentition alone was considered for those aged 12-13 years. A total of 427 subjects from 7 schools were studied. Results indicated that 81.25% of 5-6 year old subjects had dental caries (mean dmft = 4.86 +/- 4.16 S.D.) as compared to 59.6% of 12-13 year old (mean DMFT = 1.87 +/- 2.01 S.D.). The prevalence of malocclusion was 1.79% and 36.95% among those aged 5-6 year and 12-13 year, respectively. None of the 5-6 years old subjects had calculus on their teeth while 47.78% of 12-13 year old subjects exhibited the presence of dental calculus. Overall the prevalence of dental caries was found to be significantly higher among 5-6 year old subjects compared to 12-13 year old subjects. The prevalence of malocclusion and dental calculus was significantly higher among 12-13 year old subjects compared to 5-6 year old subjects.     

The relationship between bone age, chronological age and dental age in children with isolated growth hormone deficiency

Aim . To relate dental age and bone age to chronological age in a group of children with isolated growth hormone deficiency (GHD).
Design . A group of 25 children between the ages of 6 and 18 years, diagnosed as having GHD were studied. Of these, 16 were male and nine were female, undergoing replacement therapy with growth hormone (GH) over 2·5 years. Dental age (DA) was estimated from orthopantograms (Haavicko Methods) and compared to bone age (BA) by Greulich and Pyle Standards, and chronological age (CA).
Results . CA versus BA – there was a statistically significant difference of 1·52 years between the average chronological age and bone age ( t  = 5·61, P < 0·001). CA versus DA – there was a statistically significant difference of 0·92 years between the average chronological age and dental age ( t  = 3·93, P < 0·001). BA versus DA – statistically nonsignificant differences were found between the average bone age and dental age ( t  = –0·60, P  = 0·10).
Conclusion . After 2·5 years of therapy with growth hormone both DA and BA showed a significant delay compared to CA. Despite the fact that some catch-up occurs in speed of growth there is no evidence from the children in our study that might support the occurrence of a similar speed-up in dental age.     

Burnout syndrome assessment among Spanish oral surgery consultants: A two populations comparative pilot study

Background The professional Burnout Syndrome (BOS) or Burnout is considered a professional disease made up of three interrelated dimensions (emotional exhaustion, depersonalization and lack of personal fulfillment). BOS has been documented to most severely affect the healthcare professions, especially dentists. On the other hand, its appearance has been documented at an early age, during dental training. However, there are no studies that analyze its incidence in professionals dedicated to Oral Surgery and Implantology, determining the age of onset and related factors.Material and Methods The modified Maslach questionnaire was carried out anonymously among the professors and students of the Master of Oral Surgery and Implantology at the Complutense University of Madrid. A total of 36 participants were enrolled in this study and the results of the modified Maslach Questionnaire were established into four groups [1st year (n=6), 2nd year (n=6), 3rd year (n=6) postgraduate students and clinical teachers (n=18)]. The following variables were recorded: Age, sex, years of experience, weekly hours of work, dedication on weekends and scope of work. The statistical analysis performed included Pearson''s correlation, analysis of variance, Student''s t-test, F-Anova, Chi-Square and Gamma correlation. Statistical Significance of the tests was established of p≤0.05.Results 36 questionnaires were analyzed, of which 22.2% (n = 8) presented BOS, and 77.8% (n = 28) a medium risk of suffering it. The mean values and standard deviation ​​of emotional exhaustion (7.50 ± 2.43; 9.83 ± 4.12; 15.83 ± 6.21; 30.22 ± 7.86), depersonalization (5.50 ± 1.23; 50 ± 3.27; 11.33 ± 1.75; 17.56 ± 4.13), low personal fulfillment (39.67 ± 3.72; 39.33 ± 2.34; 43.17 ± 3, 55; 37.33 ± 5.51) and professional burnout (54.33 ± 2.66; 61.67 ± 2.88; 70.33 ± 5.43; 85.11 ± 9.05) in the four groups respectively. A significant association was found in the appearance of emotional exhaustion and depersonalization, years of experience, weekly work hours and the work environment.Conclusions BOS is a disease that can appear from 30 years of age, after 5 years of professional experience and when there is a clinical consultation of 40 hours a week. Oral Surgery and Implantology seems to be a risk activity for the manifestation of depersonalization. Key words:Burnout syndrome, oral surgery, dental implants, students, clinical teachers, dental education.     

A Comparative Assessment of Orthodontic Treatment Outcomes of Mild Skeletal Class III Malocclusion Between Facemask and Facemask in Combination with a Miniscrew For Anchorage in Growing Patients: A Single-center,Prospective Randomized Controlled trial

ObjectivesTo investigate the hypothesis that there is difference in the treatment outcomes of milder skeletal Class III malocclusion between facemask and facemask in combination with a miniscrew in growing patients.Materials and MethodsPatients were randomly divided into two groups. In one group, the patients were treated with facemask therapy (FM group: 12 males, eight females, average age: 10 years, 5 months ± 1 year, 8 months). In the other group, patients were treated with facemask therapy along with a miniscrew (FM+MS group: 12 males, seven females, average age: 11 years, 1 month ± 1 year, 3 months). A lingual arch with hooks was fixed to the maxillary arch in both groups and a protractive force of 500 g was applied from the facemask to the hooks. The patients were instructed to use the facemask for 12 hours per day. In the FM+MS group, a miniscrew was inserted into the palate and fixed to the lingual arch.ResultsMobility and loosening of the miniscrew were not observed during treatment. Lateral cephalometric analysis showed that SNA, SN-ANS, and ANB values were significantly increased in the FM+MS group compared with those for the FM group (SNA, 1.1° SN-ANS, 1.3° ANB, 0.8°). Increase in proclination of maxillary incisors was significantly greater in the FM group than in the FM+MS group (U1-SN, 5.0°).ConclusionsDuring treatment of milder skeletal Class III malocclusion, facemask therapy along with a miniscrew exhibits fewer negative side effects and delivers orthopedic forces more efficiently to the maxillary complex than facemask therapy alone.     

Growth patterns in the orbital region: a morphometric study.

Data for analysis of age-related changes in growth in the intercanthal (en-en) and biocular (ex-ex) widths were obtained from 1,594 healthy North American Caucasians in age groups from 1 to 18 years, divided equally between males and females. At 1 year, the degree of development of the intercanthal width reached 84.1%, and that of the biocular width 85.9% of adults in both sexes. The levels of growth achieved by 5 years of age rose to 93.3% in the intercanthal width and 88.1% in the biocular width, in both sexes. The average total growth increments achieved between ages 1 and 18 years were 5.2 mm in the intercanthal width and 12.5 mm in the biocular. The intercanthal width showed very little growth after 1 year of age; in contrast, the biocular width showed significantly greater growth increments both before and after 5 years of age. Rapid growth was observed between 3 and 4 years in the intercanthal width of both sexes. The age-related growth observed in the biocular width was small but continuous up to maturation time. The intercanthal width reached full maturation at 8 years in females and 11 years in males, and the biocular width at 13 years in females and 15 years in males.     

Streptococcus mutans levels and caries prevalence in low-income schoolchildren

Previous studies have shown that persons having high Streptococcus mutans levels in the saliva are "at risk" for dental caries. Most investigators agree, that if high levels of S. mutans were identified early in the life of at-risk children, dental decay could be reduced or eliminated through intervention. The purpose of this study is to show an association between S. mutans levels and caries prevalence in a sample of elementary school children. The study group consisted of 242 school children, ages 5-13 years. The subjects were divided into two age groups, 5-8 years and 9-13 years. Approximately 59 percent were African Americans. The sample of 242 children were equally females and males, 50 percent in each group. The Dentocult SM Test was used to make S. mutans determinations. The df-t index was used to determine the number of decayed and filled teeth of children ages 5-8 years; the DMF-T Index estimated the number of decayed, missing or filled teeth of children ages 9-13 years. Dental caries were found in 58 percent of the children (mean = 2.67, and range of 1-11). Approximately 47 percent of the children with caries had high S. mutans levels (100K-1M). Females had higher S. mutans levels than males in the 9-13 age group, p < .05. Analysis of Variance Test indicated that S. mutans levels for older females (ages 9-13) were significantly higher than those observed in males the same age (p < .01). This trend was not observed in younger children, ages 5-8 years. In addition, no significant difference or interaction was noted by sex for S. mutans levels and decayed or filled teeth (df-t) for younger children. We conclude that high levels of Streptococcus mutans are related to increased number of decayed teeth and conversely, low Streptococcus mutans levels are related to fewer dental caries. This study was supported in part by Colgate-Palmolive Company and the National Dental Association Foundation, Inc.     

Dental age in patients with impacted maxillary canines related to the position of the impacted teeth

The aim of the study was to determine whether there are differences in dental age (DA) using the method of Demirjian, in patients with impacted buccal or palatal maxillary canines in relation to unaffected controls. DA was estimated using Demirjian's method on panoramic radiographs of two groups of Caucasian patients. The study group consisted of 116 patients aged from 12 to 16 years (80 females and 36 males) that was further divided into 54 patients with unilateral or bilateral palatally impacted maxillary canines and 62 patients with buccally positioned canines. The control group of 116 subjects without canine impaction was matched to the study group by age and gender. Calculated DAs and differences between dental and chronological age (CA) were compared between the groups. Statistical analysis was performed using Shapiro-Wilk, Mann-Whitney U, and Student's t-test. DA was significantly lower in patients with impacted maxillary canines than in healthy controls and also when palatal or buccal ectopia was considered. The rate of dental development in patients with palatally impacted canines did not differ from that of subjects with buccal canine displacement. The differences between DA and CA were higher in healthy controls (increase in DA) than in patients with impacted maxillary canines. DA estimation using Demirjian's method may be lower than expected in subjects with maxillary canine impaction.     

Dental age estimation of Malay children and adolescents: Chaillet and Demirjian's data improved using artificial multilayer perceptron neural network

PurposeThe aim of this study was to assess the suitability of the 8-tooth method on the Malaysian Malays aged 5.00–17.99 years originally introduced by Chaillet and Demirjian and to develop a more reliable teeth maturity scores for age estimation based on artificial neural networks (ANN). A total of 1569 dental panoramic tomographs of Malaysian Malays aged 5.00–17.99 years were assessed. Tooth development was initially recorded using a score chart adapted from Demirjian's eight developmental stages. Maturity scores were converted to dental age (DA). The mean and standard deviation of chronological age (CA), DA and the difference between CA and DA were calculated. Artificial neural networks was then employed to develop new dental maturity scores (NDA) and its reliability was assessed.ResultsInitial comparison of known CA with estimated DA derived from Chaillet and Demirjian's dental maturity scores showed that DA was consistently underestimated by 2.09 ± 0.90 years for Malay boys and 2.79 ± 0.99 years for Malay girls for all age groups (paired t-test, p < 0.05). In order to improve the age estimation, an adaptation using artificial neural networks was employed to develop new dental maturity scores (NDA) that was more suitable for the Malay subjects. The results showed more accuracy in estimating dental age (0.035 ± 0.84 years for boys and 0.048 ± 0.928 years for girls, paired t-test, p > 0.05).ConclusionIn conclusion, the new dental maturity scores were highly accurate in estimating the age of Malaysian Malay children and adolescents.     

Comparison of body height and mandibular length between Caucasian and Japanese children

This study compared pubertal growth of Japanese males and females with that of Caucasian children matched by age and gender. Total body height and mandibular length were compared between the two groups. Total body height showed that Caucasian males were taller than Japanese males from the ages of 10 to 15 years (p< 0.01-0.05). The annual maximum growth of Caucasian females peaked at the age of twelve, but Japanese females had a "spurtless" growth pattern, peaking one year earlier than Caucasian females. Total mandibular length, calculated at the age of 10, was about 3 mm greater in Japanese males and 5 mm greater in Japanese females than in Caucasians. At the age 15, the mandibles of Japanese males and females were about 7 mm and 9 mm longer than those of Caucasians, respectively. Adolescent mandibular growth spurt occurred, on the average, at the age of 13 in both Caucasian and Japanese males. Both female groups showed mandibular growth peaks at the age of 12.     

Roentgen-cephalometric standards for a Swedish population. A longitudinal study between the ages of 5 and 31 years

This study was performed to establish age- and gender-specific cephalometric normative data for a Swedish population. The material comprised 469 lateral cephalograms from two groups of subjects of Swedish origin between 5 and 31 years of age. All subjects (males and females) were diagnosed as 'normal' according to specified criteria and with no history of orthodontic treatment. Lateral cephalograms and body height measurements were taken at 5, 7, 10 and 13 years of age in one group (group E) (longitudinal follow-up). The same registrations were made in the other group (group U) at 7, 10 and13 years of age (mixed longitudinal type). Those 13 year olds were re-examined at 16, 19 and 31 years of age (longitudinal follow-up). No significant differences between age groups in the two samples were found. Therefore, subjects of the same age were combined. The study is hence regarded as a longitudinal follow-up from 5 to 31 years of age. The subjects were also grouped into dental development stages to widen the applicability of the cephalometric data.The craniofacial distances were constantly larger in males than in females, while no statistical differences as regards angular measurements were seen between genders. Distances as well as angular measurements varied with the different developmental periods. The results clearly verify that facial pattern changes existed during the observation period, with a growth acceleration of most distances between the 13 and 16 year recordings.     

Predicting the mandibular growth spurt:: The roles of chronological age,sex, and the cervical vertebral maturation method

ObjectivesTo develop a prediction model that combined information derived from chronological age, sex, and the cervical vertebral maturation (CVM) method to predict the pubertal spurt in mandibular growth.Materials and MethodsA total of 50 subjects (29 females, 21 males) were selected from the American Association of Orthodontists Foundation Craniofacial Growth Legacy Collection, the University of Michigan Growth Study, and the Denver Child Growth study. A total of 456 lateral cephalograms were analyzed, and a multilevel logistic model was applied. The outcome variable was the presence or absence of the mandibular pubertal growth peak. The predictive variables were chronological age up to the third order, sex, presence or absence of CS 3 interactions between age and sex, age and CS 3, sex and CS 3.ResultsThe mean age ± standard deviation (SD) at the first cephalogram was 8.2 ± 0.5 years, whereas the mean age at the last cephalogram was 16.5 ± 1.1 years. The mean interval ± SD between two consecutive cephalograms was 1.0 ± 0.1 years. The mean age ± SD at the lateral cephalogram obtained immediately before the mandibular pubertal growth peak was 12.1 ± 1.1 years for females and 13.2 ± 0.8 years for males. The greatest increase in mandibular length occurred after CS 3 in 78% of the subjects. The presence of CS 3, age, second-order age, sex, and the interaction between age and sex were all statistically significant predictors of the mandibular pubertal growth spurt.ConclusionsCS 3, chronological age, and sex can be used jointly to predict the pubertal peak in mandibular growth.     

An assessment of adverse effects of antiretroviral therapy on the development of HIV positive children by observation of dental mineralization chronology

J Oral Pathol Med (2010) 39 : 35–40
Background:  The difference between dental age (DA) and chronological age (CA) indicates an advance or delay in comparison with the normal standard. Considering that DA has a very close correlation with CA in a developing child, this study aimed to investigate the relationship between the effects of antiretroviral therapy on the development of HIV positive children, by observing the timing of dental mineralization.
Methods:  A retrospective examination was made of the medical records and dental panoramic radiographs of 50 HIV-positive pediatric patients, aged 37–168 months of age. Through these radiographs, their DA was estimated and compared with their CA.
Results:  The mean DA was significantly lower than the mean CA in the entire studied sample ( P  < 0.01). There was a statistical difference between children who received antiretroviral drugs and those who used no drugs ( P  = 0.02), i.e. the non-treated individuals presented practically no difference between CA and DA, while the treated patients showed a difference of 10.67 months.
Conclusion:  We conclude that the DA of HIV infected children was delayed when compared to the CA, and there was a positive association between the use of antiretroviral therapy and a delay in the chronology of dental mineralization in the sample.     

Prevalence and severity of dental caries and treatment needs among population in the Eastern states of India

The present epidemiological investigation was conducted on a total sample of 2067 individuals in the age groups of 5-6, 15-16 and 30-35 years belonging to urban (U) and rural (R) areas of three states of eastern region of India viz. West Bengal (U & Rn = 361 & 359), Orissa (U & Rn = 351 & 351) and Sikkim (U & Rn = 323 & 321). Dental caries recording was done according to WHO index 1983. The point prevalence of dental caries, deft/DMFT and defs among all the three age groups in the urban and rural areas of three states revealed common pattern i.e. (i) Dental caries was higher in 5-6 year old children (U & R - W.B. = 52.4% & 48.3%, Orissa = 56.0% & 48.7% and Sikkim = 61.8% and 22.0% exception) as compared to 15-16 years (U & R.- WB. = 21.0% & 15.2%, Orissa = 18.3% & 19.8%, and Sikkim = 30.1% & 17.9%) and 30-35 year old individuals (U & R WB = 19.4% & 18.1% Orissa = 24.3% & 20.1% and Sikkim 29.9% & 24.5%) in West Bengal, Orissa and Sikkim respectively, (ii) dental caries was higher in urban as compared to rural areas. The decayed (d/D) component contributed maximum to total deft/DMFT and defs/DMFS score, followed by e/M (missing due to caries) and f/F component (filling) which was negligible or absent. Teeth requiring various type of treatment found that one or two surface fillings were maximum followed by others. Fluoride content of drinking water was negligible (0.004 - 0.011 ppm).     

8～12岁无鼾儿童上气道发育的X线头影测量研究

目的本研究对处于生长发育高峰期的无鼾少年儿童进行观察测量,旨在探讨年龄、颅颌面结构及周围软组织发育对上气道的影响。方法本研究样本为混合纵向资料。包括73组志愿者资料（男36例,女37例）,按年龄分为五组：8岁组、9岁组、10岁组、11岁组及12岁组。志愿者均进行整夜多导睡眠监测以排除睡眠障碍儿童,并进行头颅侧位片拍摄及测量,结果进行方差分析。结果上气道鼻咽部PNS-R（P=0．003）、UPW（P=0．001）均在8～11岁随年龄增长而增长,而在11～12岁出现下降趋势;腺样体在8～9岁间出现明显减小趋势,而在10岁后表现出增大趋势;腭咽部SPP-SPPW（P=0．01）在8～9岁间出现明显增长;UMPW及舌咽部PAS随年龄无显著性变化;SPT（P=0．05）、TGL（P=0．oo）、TGH（P=O.00）及CoMe（P=0．oo）均在10岁后表现为明显增长;v_LPw、H—CVP（P=0．00）在10岁后显著性增长。在颌骨垂直方向上N-ANS、N-Me、Co-Go随年龄增长而出现显著增大（P=0.00）。结论上气道鼻咽部生长主要受腺样体影响;舌体及软腭的生长可能会限制腭咽及舌咽部气道的生长;舌骨随年龄变化相对于脊椎向前移动可能是喉咽部气道增长的主要原因之一。     

13—18岁汉族正常[牙合]青少年上牙弓后段可利用间隙变化的纵向研究

目的探讨13—18岁汉族正常骀青少年上牙弓后段可利用间隙的增龄性变化。方法对26名汉族正常骀青少年(男12人,女14人)13—18岁每年同期拍摄头颅侧位定位片,连续6年,进行 X 线头影测量纵向分析。结果(1)13—18岁上牙弓后段可用间隙的变化存在明显的性别差异,女性每侧间隙共增长3.29mm,男性共增长5.25mm;(2)13—18岁牙弓后段可利用间隙的增加与上颌骨的生长改建及上颌磨牙近中漂移有关;(3)女性比男性较早结束颌骨的生长改建,女性14岁、男性15岁上颌后段骨改建基本结束;13—18岁期间存在上颌磨牙近中漂移现象,第二、三磨牙的萌出力可能会加速其近中漂移。结论上牙弓可用间隙的增龄性变化具有年龄、性别等差异,临床上可参考本研究结果预测相关可用间隙。