Tooth eruption and craniofacial development in congenital hypothyroidism: report of case

The long-term effects of severe hypothyroidism on craniofacial growth and dental development are illustrated in this case. It is apparent that given a favorable diet, the primary dentition can persist for a long period (early childhood to at least the age of 19) without the development of dental caries. It is also clear that the dental structures can still respond to the effects of L-thyroxine at a relatively late age, with the exfoliation of primary dentition and eruption of the secondary dentition. Impacted mandibular second molars appear to be rare. The lack of proper growth of the mandible and failure of normal resorption of the internal aspect of the ramus associated with deposition of bone on the external aspect with the development of normal-size teeth, resulted in a lack of space for the eruption of mandibular second molars. The impaction of the mandibular second molars in this patient seems to be caused by a dissociation of ramus growth and dental development, resulting in insufficient space for proper eruption of these teeth.     

Delayed eruption of premolars with periodontitis of primary predecessors and a cystic lesion: a case report

Apical periodontitis after pulp therapy in a primary tooth can cause delayed eruption of the permanent successor. A case of bilateral delayed eruption of mandibular premolars is presented. The patient. a 13-year-old girl, was referred by her dentist. Oral findings showed that the right first and left second primary molars were retained. Other premolars had erupted. An orthopantomogram revealed apical periodontitis, affecting both retained primary molars. The right first mandibular premolar was impacted against the alveolar bone and root of the second premolar, and there was a large cystic lesion in close association with the left second mandibular premolar. Both primary molars were extracted, and the cystic lesion was treated by marsupialization. Fenestration and traction were performed on the right first premolar. Correct tooth alignment was achieved with orthodontic appliances. If the problem had been detected earlier, treatment of the premolars might have been easier. Clinical and radiological follow-up, therefore, of primary teeth that have undergone pulp therapy procedures should be performed until eruption of succedaneous teeth.     

下颌第三磨牙萌出状态与舌侧骨板厚度的相关性分析

目的 分析下颌第三磨牙不同萌出状态与舌侧骨板厚度的相关性。方法 选取2016年1月—2018年12月在同济大学附属上海市第四人民医院接受下颌第三磨牙拔除术的患者187例,收集术前拔牙区锥形术CT(CBCT)影像。利用GALIEOS Viewer软件,测量下颌第三磨牙牙根中点和根尖区的舌侧骨板厚度,分析第三磨牙萌出状态与舌侧骨板厚度的相关性。采用 SPSS 22.0 软件包对数据进行Wilcoxon检验、单因素和多因素Logistic回归分析。结果 第三磨牙牙根中点区舌侧骨板的平均厚度小于根尖区(P<0.01)。牙根中点区骨板的厚度与第三磨牙的近远中向角度有关,近中阻生和水平阻生的第三磨牙,舌侧骨板较薄(P<0.01)。根尖区骨板的厚度与第三磨牙的阻生深度有关,中位和低位阻生的第三磨牙,舌侧骨板较薄(P<0.05)。结论 下颌第三磨牙舌侧骨板厚度与第三磨牙的萌出状态有关。近中、水平阻生和中位、低位阻生的第三磨牙,舌侧骨板较薄。拔牙时应避免舌侧骨板发生折裂。     

Bilateral fusion of mandibular second molars with supernumerary teeth: case report

Fusion is a developmental anomaly characterized by the union of two adjacent teeth. In this article we report a rare case of bilateral fusion of permanent mandibular second molars with supernumerary teeth. The rarity with which this entity appears, along with its complex characteristics, often make it difficult to treat. The endodontic management of one tooth is described, as well as the successful treatment of a periradicular lesion.     

Ectopic eruption of the maxillary central permanent incisors and mandibular first permanent molars: report of an unusual case.

Ectopic eruption is a disturbance in which the tooth does not follow its usual course. Among its more important etiologic factors are macrodontism, shortened arch length, posterior positioning of the maxilla, atypical eruption angle, and genetic factors. This article reports a rare case of ectopic eruption of 4 permanent teeth, maxillary central incisors and mandibular first molars, in a child aged 7 years and 11 months, in which the treatment consisted of extracting the maxillary primary central incisors and making an orthodontic intervention on the mandibular arch. A bilateral fixed appliance containing 2 hooks with loops, 1 buccal and the other lingual, was placed on the mandibular primary first molars. The hooks were activated in a niche made of light-curing resin on the occlusal surface of the mandibular permanent molars, to bring about the distal drift of these teeth. After 6 months, complete eruption of the mandibular permanent molars occurred, and a slight displacement of the maxillary permanent central incisors toward the median line was noted. The importance of early, adequate treatment is discussed.     

基于锥形束CT的多生牙新分类方法临床意义研究

 目的　应用锥形束CT（cone-beam CT，CBCT）对多生牙进行新的临床分类，并分析新分类方法的临床意义。方法　收集2016-2019年首都医科大学附属北京友谊医院口腔科的CBCT影像资料5100例，其中多生牙患者209例，共计多生牙278颗。应用CBCT对多生牙进行新的临床分类，包括萌出型、骨埋伏高位型、骨埋伏低位型、骨埋伏复杂型和牙弓外型，并分析其临床意义。结果　（1）临床资料分析：多生牙发生率为4.1%，其中有1颗多生牙的患者占76.6%，有2颗多生牙的患者占19.1%，有3颗及以上多生牙的患者占4.3%。多生牙好发部位依次为：上颌切牙区、上颌磨牙区、下颌尖牙及前磨牙区、上颌尖牙及前磨牙区、下颌磨牙区。34.9%的多生牙对邻近恒牙产生了继发影响，以萌出错位及阻生为主，主要发生在上颌切牙区。（2）新分类方法的临床意义分析：上颌切牙区多生牙以骨埋伏低位型及萌出型为主，尖牙、前磨牙及磨牙区多生牙以萌出型为主。不同类型多生牙对邻近恒牙产生继发影响的发生率不同或不全相同（χ2 = 26.057，P < 0.001），提示对邻近恒牙易产生继发影响的多生牙类型依次为：萌出型、骨埋伏复杂型、骨埋伏高位型、牙弓外型、骨埋伏低位型。结论　基于CBCT的多生牙新分类方法简单实用，其中萌出型、骨埋伏复杂型及骨埋伏高位型多生牙更易产生错牙合畸形，建议尽早拔除多生牙、定期随访，必要时正畸治疗。     

Eruption of posterior teeth in the maxilla and mandible for age determination of water deer

ObjectiveEruption of posterior teeth, including premolars and molars in the mandible rather than in the maxilla, is accepted as an accurate reference for age determination of deer. In water deer, Hydropotes inermis, the eruption age of mandibular molars has been described in two studies, but the ages were inconsistent with each other. In this study, we aimed to confirm the eruption age of mandibular posterior teeth for the accurate age determination of water deer and to evaluate the efficacy of maxillary posterior teeth for the age determination of deer.DesignThe eruption of mandibular and maxillary posterior teeth was investigated in the dry skulls of individual wild water deer of both sexes, up to an age of about 15 months.ResultsThe eruption age of mandibular molars in water deer was consistent with that of a previous study. The eruption age of posterior teeth was almost the same in the maxilla and mandible of individual water deer. The deciduous mandibular fourth premolar and the permanent maxillary fourth premolar were two easiest teeth to be identified for the age determination.ConclusionsThe former controversial eruption age of mandibular posterior teeth in water deer was confirmed. Our study first presented the eruption age of maxillary posterior teeth in water deer. It is suggested that posterior teeth not only in the mandible but also in the maxilla are useful indicators for the age determination of water deer.     

基于锥形束CT的多生牙新分类方法临床意义研究

目的　应用锥形束CT（cone-beam CT,CBCT）对多生牙进行新的临床分类,并分析新分类方法的临床意义。方法　收集2016—2019年首都医科大学附属北京友谊医院口腔科的CBCT影像资料5100例,其中多生牙患者209例,共计多生牙278颗。应用CBCT对多生牙进行新的临床分类,包括萌出型、骨埋伏高位型、骨埋伏低位型、骨埋伏复杂型和牙弓外型,并分析其临床意义。结果　（1）临床资料分析：多生牙发生率为4.1%,其中有1颗多生牙的患者占76.6%,有2颗多生牙的患者占19.1%,有3颗及以上多生牙的患者占4.3%。多生牙好发部位依次为：上颌切牙区、上颌磨牙区、下颌尖牙及前磨牙区、上颌尖牙及前磨牙区、下颌磨牙区。34.9%的多生牙对邻近恒牙产生了继发影响,以萌出错位及阻生为主,主要发生在上颌切牙区。（2）新分类方法的临床意义分析：上颌切牙区多生牙以骨埋伏低位型及萌出型为主,尖牙、前磨牙及磨牙区多生牙以萌出型为主。不同类型多生牙对邻近恒牙产生继发影响的发生率不同或不全相同（χ2 = 26.057,P < 0.001）,提示对邻近恒牙易产生继发影响的多生牙类型依次为：萌出型、骨埋伏复杂型、骨埋伏高位型、牙弓外型、骨埋伏低位型。结论　基于CBCT的多生牙新分类方法简单实用,其中萌出型、骨埋伏复杂型及骨埋伏高位型多生牙更易产生错牙合畸形,建议尽早拔除多生牙、定期随访,必要时正畸治疗。     

"Otodental" dysplasia

The case of a 3 11/12-year-old Chinese boy with the dental abnormalities of "otodental" dysplasia is reported. Hearing was normal. Dental anomalies consisted of delayed eruption of globe-shaped molars, bulbous deciduous canines, and double pulp chambers in the molars. Radiographs taken 4 years later showed taurodontic molars, supernumerary microdontic teeth, retarded formation of premolars, and probable aplasia of the mandibular second premolars.     

Extraoral inverted teeth eruption: a case report

A 14-year-old female presented with extraoral inverted eruption of left mandibular permanent molars 18 and 19 at the lower left inferior border of the mandible. Both the teeth started erupting 1 year after an extraoral surgical intervention for a discharging sinus 6 years ago. The subsequent eruption to the extraoral position of the permanent molars at the inferior border of mandible may be the result of the previous surgical procedure or pathology related to the abnormally positioned teeth. This case presents an infrequent complication affecting the adjacent permanent teeth.     

A retrospective evaluation of the eruption of impacted permanent incisors after extraction of supernumerary teeth

AIMS: Delayed eruption of teeth may be caused by the presence of one or more supernumerary teeth. The purpose of this study was to evaluate findings, predisposing factors and differentiate different techniques used that affect the outcome following removal of supernumerary teeth. A comprehensive literature review was also undertaken. METHODS: A longitudinal retrospective study was carried out at the Royal Liverpool Children's Hospital. A total of 120 patients were identified from the general anesthesia records that had supernumeraries extracted. Only 43 cases had delayed eruption of teeth caused by supernumeraries. The pre and post extraction record data collected were the gender, radiographic assessment, position of the supernumerary, age at time of referral and extraction of the supernumerary, age at time of eruption of the impacted tooth and the orthodontic and surgical management. RESULTS: The mean age of referral was 9.1 years with a male to female ratio of 4.4:1. There was a greater predilection for supernumeraries to be on the left side and be positioned palatally. Tuberculate type supernumeraries were the most frequent followed by the conical type. Spontaneous eruption of the impacted tooth occurred in 49% of cases. Eruption of the impacted tooth within eighteen months following removal of the supernumerary was observed in 91% of cases. The chronological age and space availability were the two factors that were critical in determining if eruption was spontaneous following removal of the supernumerary. CONCLUSIONS: The findings of this study reiterates the fact that given early referral, sufficient space and time, the majority of teeth prevented from erupting by a supernumerary tooth would erupt spontaneously following removal of the supernumerary alone. Randomized multi-centre prospective studies are suggested.     

Differential expressions of bilaterally unerupted supernumerary teeth

This article presents a case of bilateral unerupted supernumerary teeth in the mandibular premolar region. Surgical removal of the right-sided supernumerary tooth had to be carried out as it was impeding the eruption of the mandibular first premolar. However, its supernumerary antimere, lay dormant.     

Ectopic eruption of transposed mandibular permanent lateral incisors beneath primary first molars. Case report

Mandibular permanent lateral incisors showing bilateral transposition and ectopic eruption were seen beneath primary first molars on bitewing radiographs in a female aged 9 years. This report chronicles management of the case during the mixed dentition period. Appropriate space maintenance after extraction of mandibular primary first molars, cuspids and lateral incisors on both sides facilitated eruption and repositioning of the permanent lateral incisors without the need to sever supracrestal gingival fibres.     

Unusual surgical approach in a bilateral case of mandibular buccal infected cyst

In the new edition of WHO's "Histological typing of odontogenic tumors", the mandibular infected buccal cyst, that is associated with the lower first or second permanent molars, is considered a paradental cyst as well as the inflammatory collateral cyst, which is usually related to the lower third molar. The lesion occurs on the buccal and lateral aspects of the roots of mandibular molars with vital pulp, at the eruption time, in children aged between 6 and 10 years. The inflammation is always present in these cysts and may have an important role in their pathogenesis because it stimulates hyperplasia and cystic change of the reduced enamel epithelium or the epithelial cell rests of Malassez. The authors report the case of a 7-year-old girl, in whom both first mandibular molars were affected by an infected buccal cyst. A different surgical approach was performed with marsupialization on the left side and cystectomy on the right side. The case reported here seems to be interesting because it is the second well documented case of bilateral mandibular infected cyst associated with unerupted molars and because the adopted treatment differs from the therapeutical approach suggested in the literature. A 6-year follow-up demonstrates a correct dental and bone evolution on both mandibular molar sides.     

C1Retarded eruption of all permanent teeth. An extreme case report

Presenting problem: A 14 year old male patient with delayed eruption of all permanent teeth with the exception of maxillary first permanent molars was referred to our clinic. The clinical examination of the patient showed no signs of abnormality. Mental and physical development was normal for his age and there were no signs or symptoms supporting the presence of syndromes related to eruption problems. Blood tests were within normal limits and there was no history of such a problem in the family. Radiological examination showed that all permanent first molars were present but only the maxillary first molars had erupted. In order to achieve spontaneous eruption of their permanent successors a general practitioner extracted the central primary mandibular incisors. However no eruption of the permanent successors was observed over a period of two years. Clinical management: A decision was made to surgically expose the crowns of the permanent central incisors in the lower jaw in order to promote spontaneous eruption. A year after the operation these teeth together with the mandibular third molars were partially erupted. No other teeth had erupted at this stage. Discussion: A case of delayed eruption of all permanent teeth is very rare, especially when it is not related to any known syndrome. The pathogenesis is a diagnostic riddle and the treatment demands a very careful approach.     

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.     

Effect of extraction in the late mixed dentition on the eruption of the first premolar in Macaca nemestrina

The effect of deciduous tooth extraction in the late mixed dentition on the eruption of succedaneous teeth was studied in ten Macaca nemestrina. Nineteen deciduous teeth were extracted: nine maxillary and ten mandibular left deciduous first molars. Regardless of sex, arch, chronologic or dental age, all first premolars on the experimental side erupted before those on the control side and this pattern was statistically significant. Extraction of deciduous molars in the late mixed dentition is seen to accelerate eruption of first premolars in Macaca nemestrina. This could be the result of eliminating the need for deciduous tooth root resorption during the normal process of eruption.     

Vertical eruption patterns of impacted mandibular third molars after the mesialization of second molars using miniscrews

Objective:To investigate (1) whether vertical eruption of impacted third molars improves after mesialization of second molars and (2) what factors affect the vertical eruption of impacted third molars when space caused by missing molars is successfully closed by mesialization of the second molar using miniscrews.Materials and Methods:The treatment group (Group 1) included 52 patients who had (1) missing mandibular first molars (ML-6) or missing deciduous mandibular second molars (ML-E), (2) initially impacted mandibular third molars, and (3) successful space closure of the edentulous area with orthodontics. Panoramic radiographs at start of treatment (T1) and at time of space closure (T2) were collected. The control group (Group 2) included 46 nonedentulous patients with impacted mandibular third molars without molar protraction treatment. Panoramic radiographs with similar T1/T2 treatment times were selected. Nine measurements were obtained regarding horizontal available space, vertical eruption, and third molar angulation.Results:Third molars erupted vertically an average of 2.54 mm in Group 1 compared with 0.41 mm in Group 2. Age, gender, Nolla stage, and angle of the third molars did not show significant correlations with the vertical change of the impacted third molars, whereas the depth of third molar impaction and available space showed significant correlations.Conclusions:Impacted mandibular third molars vertically erupt as a result of uprighting with mesialization of the second molar, and vertical eruption is affected by the initial vertical location of impacted third molars and available space.     

减数磨牙矫治设计中第三磨牙相关问题的考量

正畸治疗时常会选择拔除无法保留或保留预后较差的第一或第二磨牙,或者主动减数健康的磨牙以利于纠正颌骨不调的问题.此时第三磨牙的牙根发育状况,能否顺利萌出并成功代替第二磨牙行使功能,以及如何正畸牵引阻生的第三磨牙,均是正畸治疗的难点.本文就减数磨牙矫治设计中影响第三磨牙发育及萌出的相关因素作一综述.     

Tooth eruption symmetry in functional lateralities

Dental casts and oral photographs from a cross-sectional sample of 2092 young North Americans with detailed information on functional lateralities (eyedness, handedness and footedness) were examined to compare the proportions of symmetrical and asymmetrical eruption of the antimeric (left-right, contralateral pair) permanent teeth using a four-grade eruption scale. The proportion of symmetrically erupting antimeric teeth was higher for some teeth in those with non-right-sidedness of the feet and eyes, but not significantly so in the case of handedness. Left-footedness was significantly (95% confidence interval) associated with an increased proportion of symmetrical pairs of the maxillary first molar and mandibular lateral incisor, and non-right-eyedness with an increased proportion of symmetrical eruption and left/right non-balanced proportions of asymmetrical eruption in maxillary central incisors. True right-sidedness (hand, foot and eye) was significantly (P< or =0.05) associated with advanced eruption of the left mandibular first molar. It is suggested that while the timing of antimeric tooth emergence and clinical eruption is primarily programmed before crown mineralization, starting approximately at the 30th gestational week in the case of first permanent molars, symmetrical/asymmetrical tooth emergence and eruption may provide information a posteriori on prenatal and early postnatal growth and development.