原发性牙齿萌出障碍(PFE)的研究现状

原发性牙齿萌出障碍(PFE)是一种比较罕见的牙齿萌出异常性疾病,它是由于萌出机制本身异常而导致的牙齿萌出障碍,而非其他局部或全身因素所致。发病机制尚不十分明确,可能与基因突变有关,甲状旁腺激素受体1(PTH1R)突变是已经被证实的病因之一。临床表现以牙齿萌出不全和后牙开牙合为主要特征,正畸牵引无效。因其具有明显的家族聚集性,基因遗传分析是必要的辅助检查手段,对PFE的筛查、诊断和治疗具有重要意义。目前PFE尚无较好的治疗方法,可摘局部义齿、种植义齿和外科手术治疗等是可以参考的治疗手段。该文将从PFE的发病机制、临床特征、诊断和治疗等方面的研究现状作一综述。     

原发性牙齿萌出障碍的研究进展

原发性牙齿萌出障碍（PFE）是一种十分罕见的疾病,它并非由临床检查可发现的局部或全身因素所致,而是由牙齿萌出机制本身出现异常导致的牙齿萌出障碍。PFE常影响恒磨牙,造成严重的后牙开,其诊断和治疗均较为困难。本文就PFE的临床特征、发病机制、临床诊断和治疗等方面的研究进展作一综述。     

升高咬合对青春期大鼠髁突软骨BMP-2表达变化的影响

目的 观察升高咬合后髁状突软骨骨形成蛋白-2(BMP-2)的表达。方法 40只5周龄雄性SD大鼠,随机分为4组对照组和4组实验组(双侧后牙板升高咬合)。实验组与对照组动物分别在第7、14、21及28天时处死。取其右侧髁突,采用SABC免疫组化方法观察髁突软骨细胞BMP-2阳性细胞的分布及含量改变。结果 与对照组相比,实验组髁突软骨细胞BMP-2阳性细胞表达在实验第7、14天明显减少,第28天明显增多(P<0.05)。结论 咬合升高后引起髁突软骨BMP-2高表达,髁突软骨发生适应性改建。     

甲状旁腺相关蛋白对鼠胚髁突软骨细胞增殖和分化的调控

目的 探讨甲状旁腺相关蛋白（PTHrP）对鼠胚髁突软骨细胞增殖和分化的影响。方法 在体外分离培养鼠胚髁突软骨细胞的基础上,观察PTHrP对其软骨结节形成、碱性磷酸酶（ALP）活性等的影响。结果 研究发现加入浓度分别为0.01 nmol/L、0.1 nmol/L、1 nmol/L、10 nmol/L的PTHrP后,0.01 nmol/L组与对照组相比,形成的软骨结节数量在统计学上无显著性差异（P>0.05）,而软骨结节数量从0.1 nmol/L组开始与对照组相比明显增加,统计学上
有显著性差异（P<0.05）。而ALP活性在0.1-10 nmol/L组与对照组相比明显升高,统计学上有显著性差异（P<0.05）。阻断其受体后,实验组和对照组软骨结节形成的数目明显减少（P<0.05）,而对其ALP活性的影响在实验组和对照组之间无显著性差异（P>0.05）。结论 PTHrP通过其受体具有促进髁突软骨细胞增殖和分化的作用,其调控机制与其在生长板软骨细胞及下颌膜内成骨中的作用相似。     

CSF-1和PTHrP对人牙囊细胞OPG表达的影响

目的:研究集落刺激因子(colony-stimulating factor-1,CSF-1)和甲状旁腺相关蛋白(parathyroid hor-mone-related protein,PTHrP)对体外培养的人牙囊细胞(dental follicle cells,DFC)表达骨保护素(osteo prote gerin,OPG)的影响。方法:原代培养人牙囊细胞,选第3~6代细胞,培养基中分别加入不同浓度的CSF-1和PTHrP与牙囊细胞共同孵育,MTT法检测人牙囊细胞的增殖活性;Sandwich ELISA测定培养上清液中OPG的含量。结果:25ng/ml的CSF-1和10ng/ml的PTHrP可以促进DFC增殖,并且此浓度两种因子分别与DFC共培养OPG表达均降低(P<0.05)。结论:在牙齿萌出的某时期牙囊自分泌和旁分泌的CSF-1和PTHrP有降低人牙囊细胞OPG表达的作用。     

西安市青少年恒牙萌出时间及恒牙萌出与生长发育关系的调查

目的：调查西安市青少年、儿童恒牙萌出的时间、顺序和性别差异,分析恒牙萌出与生长发育间的内在联系。方法：在西安市幼儿园、小学和中学随机选取6755名年龄2～17岁青少年,收集恒牙萌出横断面调查资料,其中男3637名,女3118名,对受试者资料进行统计学分析。结果：女性受试者所有恒牙萌出的平均时间早于男性,萌出顺序也不同：除第一、第二前磨牙外,下颌牙的萌出早于上颌同名牙。大多数恒牙初萌时间与身高、体重间有显著的低度相关关系（P〈0．05）。结论：调查结果与以前国内其他地区的调查结果之间存在差异,对临床工作有理论指导意义。     

Age and order of eruption of primary teeth in Spanish children

Abstract – A longitudinal study on primary tooth eruption was performed in 114 Spanish children in two Primary Care Centers over 3 yr. Data from periodic observations and data collected by previously instructed parents was studied. Ages of tooth eruption were calculated for both sexes. Comparison between the two sides of the jaws showed a nonsignificant tendency towards earlier left side eruption. Comparison between maxillary and mandibular showed a significant earlier mandibular eruption for central incisors and second molars and a significant earlier maxillary eruption for lateral incisors. Comparison between sexes showed a tendency towards earlier eruption in boys for all teeth, significant only for mandibular central incisors, maxillary and mandibular lateral incisors and mandibular canines. Order of tooth eruption and its most frequent changes were also studied. When these findings were compared to studies performed in other populations it was concluded that ages and order of primary tooth eruption in Spanish children are similar to those found in other populations.     

6 712名少年儿童恒牙萌出时间和顺序的调查研究

目的:调查分析西安市少年儿童恒牙萌出的时间、顺序和性别差异,为口腔医师进行咬合诱导等治疗提供理论参考。方法:在西安市8所幼儿园、小学和中学中整群抽取6712名年龄为3～15岁的少年儿童,收集恒牙萌出横断面调查资料,其中男性3604名,女性3108名,对各项数据进行统计分析。结果:左右两侧同名牙同时萌出,除第一、第二前磨牙外,下颌恒牙萌出早于上颌同名牙;大多数恒牙的萌出时间女性早于男性,萌出顺序也有所不同。结论:结果与以前国内其他地区的调查结果有一定不同。     

Emergence of permanent teeth and onset of dental stages in Japanese children

The purpose of the present cross-sectional study was to provide mean times of emergence of permanent teeth and onset of dental stages in Japanese children. A total of 1819 schoolchildren aged 6-15 yr were recorded. The results demonstrated specific sequences of emergence in the two arches and earlier emergence times in girls than in boys, both findings in keeping with investigations on other ethnic groups. Secular trend in tooth emergence was studied by comparing the results with data on Japanese children in 1934. The comparison revealed earlier mean times of emergence in general in contemporary Japanese.     

Timing of permanent tooth emergence in a Southeastern Dominican schoolchildren population sample

Abstract The purpose of this study was to establish the mean timing of permanent tooth emergence in a low to middle socioeconomic level schoolchildren population sample from the Southeastern part of the Dominican Republic. A total of 900 children (15.6%of the 5–14-year-old schoolchildren from this city) were studied. Girls were relatively advanced in their emergence times except for the canine and second premolar in the maxilla and the first premolar in the mandible. The mean emergence times were, in general, relatively advanced when compared with those of United States whites and blacks, Danish, Canadian Eskimos, French-Canadians, Greenland Eskimos, Icelandics, Southern Chinese and South Africans.     

Effects of antiresorptive medications on tooth root formation and tooth eruption in paediatric patients

Tooth eruption is a pivotal milestone for children's growth and development. This process involves with the formation of the tooth root, the periodontal ligament (PDL) and the alveolar bone, as the tooth crown penetrates the bone and gingiva to enter the oral cavity. This review aims to outline current knowledge of the adverse dental effects of antiresorptive medications. Recently, paediatric indications for antiresorptive medications, such as bisphosphonates (BPs), have emerged, and these agents are increasingly used in children and adolescents to cure pathological bone resorption associated with bone diseases and cancers. Since tooth eruption is accompanied by osteoclastic bone resorption, it is expected that the administration of antiresorptive medications during this period affects tooth development. Indeed, several articles studying human patient cohorts and animal models report the dental defects associated with the use of these antiresorptive medications. This review shows the summary of the possible factors related to tooth eruption and introduces the future research direction to understand the mechanisms underlying the dental defects caused by antiresorptive medications.     

Failure of tooth eruption in two patients with cerebral palsy and bruxism—a 10-year follow-up: a case report

The aim of this paper was to analyze delayed tooth eruption in two children with cerebral palsy who had severe bruxism and to determine whether treatment could influence tooth eruption and alignment. Extraction of primary teeth was carried out and orthodontic treatment was considered due to severe tooth wear of primary teeth, lack of space, and development of a class III malocclusion.
Analysis was based on clinical examination, photographs, radiographs, and dental casts.
In both patients, early mixed dentition was delayed for more than 5 years. Calcification and root development of posterior permanent teeth corresponded with the chronological age. Root resorption of the severely abraded primary teeth and eruption of their successors were delayed or failed. Eruption of permanent teeth occurred slowly after primary teeth were extracted. Orthodontic treatment succeeded in one patient, achieving a normal overjet in combination with a successful orofacial therapy.
The disturbed exfoliation of abraded primary teeth and failure of tooth eruption of the posterior teeth could be linked to the systemic pathology and to bruxism. At age 20, eruption of the canines and premolars remained questionable.     

Gingival vasculature around erupting deciduous teeth of dogs and cats

Abstract The presence of plaque and of overt inflammation, occurring with eruption of deciduous teeth in dogs and cats 2–14 weeks old, were related to the concomitant gingival vascular morphology, using vital microscopy, perfusion and histological techniques. Although localised, acute inflammation accompanied plaque formation at the time of weaning, it seldom developed into chronic inflammation. The onset of overt chronic inflammation was not related to tooth eruption or to events associated with formation of the gingiva. Infiltration of gingival tissue by chronic inflammatory cells occurred in only a few specimens and was associated with increased plaque and replacement of the gingival vessel network by loop patterns.     

Sexual dimorphism of primary dentition in Spanish children

Aim: To analyse differences in the eruption of primary teeth between both sexes.

Materials and methods: A cross-sectional study was performed in a sample of 1250 children aged between 3 and 42 months. The clinical emergence of teeth was taken to estimate average ages for primary teeth eruption. The t-test was used to analyse gender and arch differences.

Results: Eruption of primary teeth began at the same time in girls as in boys; although the eruptive process was longer in girls. It was observed that almost all deciduous teeth emerged earlier in boys, except for the first molar (upper and lower) and the maxillary central incisors. The differences were statistically significant for almost all the primary teeth except for the central incisors, both upper and lower.

Conclusions: By comparing the timing of the eruption of primary teeth in both sexes, it was found that eruption of almost all primary teeth took place earlier in boys than in girls and that the eruption process was shorter for boys than for girls. Most of the deciduous teeth erupted earlier in the right side in both sexes. No differences were found in the sequence of eruption of primary teeth between genders.     

Eruption times of permanent teeth in children and young adolescents in Athens (Greece)

In a study in Athens, Greece, during the summer of 2003, 2,304 patients (1,168 boys and 1,176 girls) were examined by a young dentistry. The examination occurred within the framework of a routine dental check-up performed at the National and Kapodistrian University of Athens. The age span ranged from 3.00 to 24.93 years of age. Sex, age and present permanent teeth were recorded. Wisdom teeth were excluded. The sequence of tooth eruption differs significantly in the lower and upper jaw, whereas no significant differences existed when comparing the sides of each jaw. The tooth eruption in the lower and upper jaw of male and female probands is symmetrical. In comparing the upper and the lower jaw of both genders, it becomes evident that there is a tendency for earlier tooth eruptions in the lower jaw. In respect to the tooth eruption sequence, a change was noted in the upper jaw. Contrary to the reports of other authors, the second premolar has changed places with the canine and erupts prior to this tooth. This could also be demonstrated in recent studies from New York and Bremen (Germany). Otherwise no major differences concerning the sequence of tooth eruptions were observed, when compared with the results gained from other populations. Concerning the entire dentition, no acceleration of the tooth eruption could be noted. The computed differences of teeth eruption as a mean value calculated over all teeth was ±1 year at maximum, compared with studies from different continents. Oral examination of teeth is a simple tool to calculate tooth eruption intervals. This first investigation in a population of Athens revealed a change in the eruption sequence of permanent teeth. These findings are relevant for dental treatment planning and should be reconfirmed at certain intervals.     

牙齿萌出过程中 RANKL mRNA 的表达与破骨细胞的关系

目的:探讨核因子κB受体活化剂配体 RANKL 在大鼠下颌第一磨牙牙胚冠方组织中 mRNA 的表达及破骨细胞的分化情况.方法:运用原位杂交法检测大鼠下颌第一磨牙牙胚冠方组织中 RANKL mRNA 的表达;TRAP 染色观察破骨细胞分化情况.结果:出生1、3、5、7 d大鼠下颌第一磨牙牙胚冠方牙囊成纤维细胞、成釉细胞 RANKL mRNA的阳性表达强于对照组牙龈成纤维细胞(p<0.01).大鼠下颌第一磨牙牙胚冠方出生后1 d破骨细胞多为单核,3 d时多核破骨细胞增多.结论:RANKL mRNA 在大鼠出生后1、3、5、7 d下颌第一磨牙牙囊成纤维细胞、成釉细胞中有表达,可能通过促进破骨细胞的分化及成熟参与牙齿的萌出.