牙齿发育异常及颅面异常综合征致病基因研究的新进展

基因突变是导致牙颌面畸形的重要原因。目前我国牙颌面畸形的发病率高达67．87％，其中遗传性畸形占有较高的比例。随着人类基因组计划的完成和功能基因组计划的实施以及生命科学领域前沿技术向口腔医学的广泛渗透，一系列牙颌面畸形相关基因及其突变正在被逐步阐明。以下拟从先天性牙齿缺失、多生牙、牙本质发育不全、颌骨及软组织异常、非综合征性唇腭裂畸形五个方面概述相关基因及其突变的最新进展。     

Fetal alcohol syndrome and developing craniofacial and dental structures--a review

OBJECTIVES: Fetal alcohol syndrome (FAS) is a collection of signs and symptoms seen in children exposed to alcohol in the prenatal period. It is characterized mainly by a distinct pattern of craniofacial malformations, physical and mental retardation. However, with the increased incidence of FAS, there is a great variation in the clinical features of FAS. DESIGN: Narrative review. RESULTS: This review describes data from clinical and experimental studies, and in vitro models. Experimental studies have shown that alcohol has a direct toxic effect on the ectodermal and mesodermal cells of the developing embryo, particularly in the cells destined to give rise to dentofacial structures (i.e. cranial neural crest cells). Other effects, such as, abnormal pattern of cranial and mandibular growth and altered odontogenesis are described in detail. The exact mechanism by which alcohol induces its teratogenic effects remains still unknown. The possible mechanisms are outlined here, with an emphasis on the developing face and tooth. Possible future research directions and treatment strategies are also discussed. CONCLUSION: Early identification of children affected by prenatal alcohol exposure leads to interventions, services, and improved outcomes. FAS can be prevented with the elimination of alcohol consumption during pregnancy. We need to provide education, target high-risk groups, and make this issue a high priority in terms of public health.     

Axenfeld-Rieger syndrome: report on dental and craniofacial findings

Axenfeld-Rieger syndrome is a rare autosomal dominant disorder characterized by various ocular and extraocular malformations. Dental abnormalities are considered as definitive features for the diagnosis and differentiation of Rieger syndrome from other anterior chamber of the eye malformations. A case of Rieger syndrome with distinct dental and craniofacial anomalies is described. Significant cranio-dento-facial findings that have been observed are, teeth with short and dilacerated roots, hyperplastic frenums and underdeveloped maxilla. There was an anterior crossbite, bilateral posterior open-bite and moderate to severe anterior crowding.     

Relationship between occlusal plane determinants and craniofacial structures

A cephalometric study was conducted on 34 complete denture wearers to investigate the relationship between the anatomical structures commonly used to determine the occlusal plane and the facial skeletal shape. The results showed no correlation between the shape of the skeletal face, the gonial angle and the length of the mandible versus the location of the retromolar pad, the occlusal plane and Camper's plane. However, a statistically significant linear correlation (P < 0.0001) was found between the facial skeletal shape designated SN POG and the location of Camper's plane. Cephalometric analysis alone cannot determine the location of the occlusal plane in edentulous patients. Intra-oral structures should also be considered.     

Associations between mandibular symphysis form and craniofacial structures

Objectives

This study aimed to (1) analyze the relationships between mandibular symphysis characteristics (height, prominence, inclination, concavity, and convexity) and facial pattern, skeletal class, lower incisor position, and sex, and (2) determine the associations between the symphysis soft tissue dimensions and the underlying osseous structures.

Methods

Cone-beam computed tomography (CBCT) images were selected for 385 patients (206 women and 179 men). The patients were classified according to their skeletal class and vertical pattern. The lower incisor inclination (IMPA) was recorded. Twelve measurements were taken for each mandibular symphysis using Invivo5 software (Anatomage, San Jose, CA, USA).

Results

Symphyseal measurements were larger in males than in females. Skeletal Class II and III hyperdivergent patients showed the highest symphysis height values. Hypodivergent individuals showed lower symphysis convexity angles. Concavity of the symphysis was greater for Class II hyperdivergent patients. Lower incisor inclination showed a positive correlation with symphysis concavity and inclination. Moderate and weak correlations were found between hard tissue and soft tissue parameters.

Conclusions

Only a few characteristics of symphysis morphology depend on sex, incisor position, skeletal class, and vertical pattern. More significant relationships are found when the vertical pattern and skeletal class are analyzed in combination. The shape of the symphysis soft tissue is not directly correlated with the underlying skeletal structures.

     

Association between alcohol consumption and dental health

Objectives: To study the association of alcohol consumption with dental health in a sample from the County of Stockholm. Material and Methods: In a longitudinal investigation, 513 individuals were examined in 1970 and 1990. Clinical and radiographic examinations were performed as well as an interview including questions on alcohol consumption. The clinical investigation consisted of the registration of the number of remaining teeth, dental restorations, caries and periodontal conditions. The marginal bone level and longitudinal bone loss were determined by assessments on the proximal surfaces of all measurable teeth on the radiographs. Stepwise multiple regression analyses were adopted to calculate the partial correlations between alcohol consumption and the investigated odontological variables. Results: The group of subjects with the highest alcohol consumption (>5 cl pure alcohol per day) had more tooth surfaces with caries, more calculus and more teeth with apical lesions compared with those who reported an alcohol consumption 5 cl of pure alcohol per day. Alcohol consumption was not associated with periodontal disease. Conclusion: The observations do not support any association between alcohol consumption and periodontal disease. However, individuals with high alcohol consumption had significantly more teeth with decayed surfaces and apical lesions indicating that lifestyle‐related factors may influence dental health.     

儿童呼吸方式与颅面、气道、牙(牙合)形态的相关性研究

目的研究儿童呼吸方式与颅面、气道、牙骀形态的相关性。方法选择72例11～14岁的正畸科初诊患者，使用口鼻气流同步测量仪测量其口、鼻气流比例并计算口呼吸比例，在X线头影测量片和牙模型上测量颅面、气道、牙骀的形态学指标86项，通过t检验筛选出16项有统计学意义及临床意义的指标，进行多元回归分析（向后法）和简单直线回归分析。结果下面高与全面高之比（ANS-Me／N-Me）、下颌角（Ar-Go-Me）、扁桃体或舌根后缘与咽后壁的最小距离（P-T）、上颌基骨宽度（SHJK）与口呼吸比例的密切程度逐渐降低（P〈0．05），多元回归系数分别为3．359，0．012，-0．013，-0．021。结论儿童呼吸方式与颅面形态具有一定相关性。     

儿童呼吸方式与颅面、气道、牙形态的相关性研究

目的研究儿童呼吸方式与颅面、气道、牙形态的相关性。方法选择72例11～14岁的正畸科初诊患者,使用口鼻气流同步测量仪测量其口、鼻气流比例并计算口呼吸比例,在X线头影测量片和牙模型上测量颅面、气道、牙的形态学指标86项,通过t检验筛选出16项有统计学意义及临床意义的指标,进行多元回归分析(向后法)和简单直线回归分析。结果下面高与全面高之比(ANS-Me/N-Me)、下颌角(Ar-Go-Me)、扁桃体或舌根后缘与咽后壁的最小距离(P-T)、上颌基骨宽度(SHJK)与口呼吸比例的密切程度逐渐降低(P<0.05),多元回归系数分别为3.359,0.012,-0.013,-0.021。结论儿童呼吸方式与颅面形态具有一定相关性。