锁骨颅骨发育不全综合征(CCD)的牙面畸形特征分析

目的：分析锁骨颅骨发育不全综合征牙面畸形的表现.方法：收集15年（1990～2004年）诊断为锁骨颅骨发育不全综合征（CCD）患者.其中男性2例、女性2例,就诊时年龄12～18岁,平均年龄14.2岁.所有病例均填写病历、询问其囟门关闭情况,并拍摄胸片,上下颌骨曲面断层片,头颅正、侧位片位,TMJ片、面（牙合）像.结果：1）4例均有多生牙,2）乳牙滞留,3）颌骨发育异常,下颌骨发育过度、上颌骨正常或发育不足,下颌肥大、反（牙合）面型.牙槽骨较一般致密,局部区域骨小梁排列致密.4）4例患者均表现面部异常,头大面小,面下1/3短.眶间距较正常人大且颧弓突出、下弯.结论：分析锁骨颅骨发育不全综合征牙面畸形的表现有助于临床诊断.     

Retrospective analysis of factors influencing the eruption of delayed permanent incisors after supernumerary tooth removal.

AIM: This was to assess the predictability of eruption of delayed permanent incisors after supernumerary removal and creation of adequate space, in relation to: root maturity, degree of vertical impaction, and degree of angulation of impaction. METHODS: The dental records of children with supernumerary teeth delaying the eruption of permanent incisors were analysed. The type of a supernumerary tooth, its location and position were recorded, along with the stage of root maturation, angulation and vertical distance of impaction of the permanent incisor. At the initial surgery, the unerupted supernumerary tooth and any retained primary incisors were removed. The unerupted permanent incisor was not exposed. If necessary, the maxillary primary canines were removed to create sufficient space for eruption of the delayed permanent tooth. A secondary surgical procedure was planned after 18 months if there was no significant progress of the permanent tooth towards eruption. STATISTICS: All data were entered onto a Microsoft Excel spread sheet and analysed using Fisher's Exact Tests throughout due to the small numbers. RESULTS: Sixty-six supernumerary teeth were removed, 22 from boys and 44 from girls with ages ranging from 6 to 10 years 6 months at the time of surgery. Primary canines were extracted in 59.1% of cases. Spontaneous eruption occurred in 89.4% of delayed permanent teeth. The mean time to eruption was 9.2 months (median = 7 months). There was no statistically significant association between tooth eruption and root maturity or the degree of vertical impaction. There was an association between eruption and the degree of the angle of impaction of the permanent incisor (p<0.05). CONCLUSION: The majority of delayed permanent teeth erupt spontaneously if sufficient space is available or created at the time of removal of the unerupted supernumerary. The angulation of impaction of the permanent incisor is associated with a delay in eruption.     

An assessment of root cementum in cleidocranial dysplasia

The purpose of this prospective study was to determine if there is a difference between the amount of cellular and acellular cementum on the roots of 2 teeth extracted from a subject with cleidocranial dysplasia (CCD) compared to 10 teeth extracted from 10 subjects unaffected by CCD. The cementum of 2 permanent teeth, which had been extracted from the CCD subject, was examined and histomorphometrically analyzed for comparison to the cementum of 10 anterior teeth that had been extracted from individuals who were unaffected by CCD. The percentage of the root covered by cellular or acellular cementum was quantified to determine if patients affected by CCD typically lack cellular cementum. In the roots of the 2 permanent teeth of the subject with CCD, a mean of 18.05 +/- 10.67% was covered by cellular cementum and 76.90 +/- 3.53% was covered by acellular cementum. In the 10 permanent teeth from subjects without CCD, a mean of 19.12 +/- 15.60% of the root was covered by cellular cementum and 80.34 +/- 15.71% was covered by acellular cementum. The findings indicate that there is no statistically significant difference between the amount of either cellular or acellular cementum covering the roots of the study subject with CCD and the roots of the 10 control teeth. The presumption that a lack of cellular cementum causes the increased number of unerupted teeth in patients with CCD is not supported by the findings of this study.     

Diversity of supernumerary tooth formation in siblings with cleidocranial dysplasia having identical mutation in RUNX2 : possible involvement of non-genetic or epigenetic regulation

INTRODUCTION: Cleidocranial dysplasia (CCD, MIM #119600) is an autosomal-dominant disorder characterized by hypoplasia or aplasia of clavicles, patent fontanelles and short stature. The responsible gene has been identified as RUNX2. CCD is also accompanied by characteristic dental abnormalities, e.g. supernumerary teeth, delayed eruption and impaction of permanent teeth. Intrafamilial variations of skeletal abnormalities are reported but those of dental abnormalities are obscure. To clarify this point, a precise examination of the dental features of CCD siblings having identical mutation was performed. DESIGN: Gene mutational analysis of three Japanese CCD siblings and their father was performed. Skeletal and dental characteristics were examined by the inquiry and radiographs. RESULTS: Three siblings uniformly showed patent fontanelles and short stature. They and their father had a novel missense mutation in the RUNT-domain (P210S) of RUNX2. The siblings were completely discordant for the dental characteristics with the position and number of supernumerary teeth being completely different. The youngest, a 12-year-old boy, had six supernumerary teeth, which appeared symmetrically around the maxillary canines and mandibular premolars. The second, a 15-year-old girl, had four supernumerary teeth which appeared around the mandibular incisors. The oldest, a 17-year-old boy, had 11 supernumerary teeth, which were symmetrically around the mandibular lateral dentition and asymmetrically around the maxillary incisors and premolars. CONCLUSION: The present study suggests the involvement of non-genetic or epigenetic regulation in supernumerary tooth formation in CCD.     

A premaxilla with a supernumerary tooth indicating a developmental region with a variety of dental abnormalities: a report of nine cases

The aim of this study was to elucidate whether a premaxilla with a supernumerary tooth has additional dental abnormalities. The study does not include premaxillas with a mesiodens, only premaxillas with parasagittally located supernumerary teeth. Radiographs from eight children, followed from 1 year and 5 months to 11 years and 5 months in the municipal dental health service in Denmark, were analyzed. One patient was seen only once. Dental abnormalities recorded included: invaginations on permanent incisors, resorption of roots of incisors, curved roots of incisors, delayed eruption, and delayed formation of roots. The study shows that there are dental abnormalities within the premaxillary region where the supernumerary tooth is located. This indicates that, apart from the supernumerary tooth, a more widespread deviation from normal conditions including tooth malformation, arrested eruption, and root resorption occur within the premaxillary region. The most important outcome of this study is that in the region with a supernumerary tooth the adjacent incisor shows delayed eruption after surgical removal of the supernumerary tooth. The deviations in root morphology, including root resorption, are not limited to patients who have had orthodontic treatment, but patients who did not receive orthodontic treatment also revealed deviations in root morphology. Therefore the treatment outcome can be different from the expected outcome.     

A premaxilla with a supernumerary tooth indicating a developmental region with a variety of dental abnormalities: a report of nine cases

The aim of this study was to elucidate whether a premaxilla with a supernumerary tooth has additional dental abnormalities. The study does not include premaxillas with a mesiodens, only premaxillas with parasagittally located supernumerary teeth. Radiographs from eight children, followed from 1 year and 5 months to 11 years and 5 months in the municipal dental health service in Denmark, were analyzed. One patient was seen only once. Dental abnormalities recorded included: invaginations on permanent incisors, resorption of roots of incisors, curved roots of incisors, delayed eruption, and delayed formation of roots. The study shows that there are dental abnormalities within the premaxillary region where the supernumerary tooth is located. This indicates that, apart from the supernumerary tooth, a more widespread deviation from normal conditions including tooth malformation, arrested eruption, and root resorption occur within the premaxillary region. The most important outcome of this study is that in the region with a supernumerary tooth the adjacent incisor shows delayed eruption after surgical removal of the supernumerary tooth. The deviations in root morphology, including root resorption, are not limited to patients who have had orthodontic treatment, but patients who did not receive orthodontic treatment also revealed deviations in root morphology. Therefore the treatment outcome can be different from the expected outcome.     

Histological and analytical studies of a tooth in a patient with cleidocranial dysostosis

A histopathological and analytical study of a permanent tooth from a patient with cleidocranial dysostosis (CCD) was performed. The patient was a 47-year-old woman, who had 10 erupted permanent teeth and 2 partially erupted and 19 completely impacted teeth, including supernumerary teeth. The erupted right upper premolar was extracted and observed using a light microscope and an electron probe X-ray microanalyzer (EPMA). Findings showed enamel hypoplasia, predominantly irregular globular dentin and Tomes' granular layer, and a complete lack of cellular cementum in the ground section. The incremental von Ebner and counter Owen lines were obscure. Comparative quantitative analysis using the EPMA showed that the quantities of calcium and phosphate were lower in the enamel and dentin than those of the control sample.     

Delayed tooth eruption and suppressed osteoclast number in the eruption pathway of heterozygous Runx2/Cbfa1 knockout mice

Genetic studies have recently identified a mutation of one allele of runt-related gene 2 (RUNX2/CBFA1) as the cause for an autosomal-dominant skeletal disorder, cleidocranial dysplasia (CCD), which is characterised by hypoplasia of the clavicles and calvariae and widened sutures and fontanelles. In addition, CCD is frequently affected with multiple supernumerary teeth and the impaction and delayed eruption of teeth, the causes of all these dental abnormalities are still unknown. To clarify the cellular mechanism of the delayed tooth eruption in CCD, the process of tooth eruption was examined in heterozygous Runx2/Cbfa1 (mouse homolog of RUNX2/CBFA1) knockout mice, known to mimic most of the bone abnormalities of CCD. The timing of the appearance of maxillary and mandibular teeth into the oral cavity was significantly delayed in heterozygous mutant mice compared with wild-type mice. From postnatal days 8 to 10, an active alveolar bone resorption and a marked increase of the osteoclast surfaces was observed in the eruption pathway of both genotypes, but this increase was significantly suppressed in the mutant mice. In contrast, the osteoclast surfaces did not show a significant difference between the two genotypes in the future cortical area of femora. These results suggest that haploinsufficiency of Runx2/Cbfa1 does not effect the femoral bone remodelling but is insufficient for the active alveolar bone resorption essential for the prompt timing of tooth eruption. These results also suggest the possibility that impaired recruitment of osteoclasts is one of the cellular mechanisms of delayed tooth eruption in CCD patients.     

Supernumerary teeth diagnosis and treatment approach. Six case reports

Supernumerary teeth are relatively common in the general population, affecting the primary and the permanent dentition and have been reported in many genetic syndromes. They are classified according to form and shape. Seven different examples of hyperodontia are presented to highlight the numerical and morphological variation in dental abnormalities manifestations, empathising the importance of thorough clinical and radiological examination and of a correct therapeutic approach. The patients presented single or multiple hyperodontia, with particular interest for a 12 supernumerary teeth case. The clinical problems linked to supernumerary teeth were: impaction or ectopic eruption, crowding, possible root resorption of adjacent teeth. The therapeutical approach of supernumerary teeth varied on the position of the element in excess and on the complexity of the clinical case. In some cases the single extraction of the supernumerary tooth was indicated, while in other cases the extraction of the tooth was needed in addition to orthodontic treatment to gain sufficient space for the tooth with delayed eruption.     

A Case of Cleidocranial Dysostosis: Dilemma for a Prosthodontist

Cleidocranial dysostosis (CCD) is an uncommon, generalized skeletal disorder characterized by delayed ossification of the skull, aplastic or hypoplastic clavicles, and complex dental abnormalities such as retention of multiple deciduous teeth, impaction or delayed eruption of permanent teeth and presence of supernumerary teeth. This case report describes a 30-year old male patient of CCD with classical findings and the challenges faced in his prosthodontic rehabilitation. Conventional complete dentures following interim complete dentures therapy had to be given as all other treatment modalities were ruled out because of anatomic limitations. Despite the disadvantages of removable dentures the patient adapted admirably to them with significant improvement in self-esteem. Though orthodontic and surgical correction may be the treatment of choice, the need to preserve the alveolar ridge could make fabrication of removable dentures in such patients, a viable option.     

Morphogenetic and functional characteristics of coronal cementum in bovine molars

Abstract— Coronal cementum in bovine teeth has been implied to be homologous with enamel cuticles in man. A radiographic and histologic study of the life cycle of the bovine first permanent molar was undertaken in order to test the validity of this view. Formation of coronal cementum was found to be preceded by a total disintegration of the reduced enamel epithelium and to start in the cuspal area before eruption of the tooth into the oral cavity. Fibrous attachment of the connective tissue to the coronal cementum thus prevented the formation of a deep gingival pocket around the erupting tooth. Shortly after the tooth had reached occlusion, cementum was found to cover the enamel all the way to the apical enamel border. The tooth was thus attached not only by its short root but also by a substantial area of its anatomical crown. With advancing age, occlusal wear and subsequent progressive eruption of the tooth resulted in an apposition of multiple layers of cellular cementum on both the root and cervical enamel surfaces, Neither its morphogenetic characteristics nor its vital function in tooth attachment seemed to indicate that coronal cementum in bovine teeth corresponds to enamel cuticles in man.     

Development of the dentition in cleidocranial dysplasia

The purpose of the present investigation was to describe the formation, maturation and eruption of the dentition, including supernumerary teeth in a sample of patients with cleidocranial dysplasia. The dentition was evaluated from orthopantomograms, intraoral radiographs, cephalometric films, surgically removed teeth and intraoral photographs in 19 patients (9 men, 10 women), aged 3.5 to 34 years. Formation of primary teeth was normal, whereas all patients but one had supernumerary permanent teeth. Frequency of supernumerary teeth ranged from 22% in the maxillary incisor region to 5% in the molar regions. Supernumerary teeth were formed lingually and occlusally to the normal teeth. Maturation of the primary dentition was normal, while permanent teeth were delayed from 1 to 4 yr. Supernumerary teeth were delayed about 4 years in relation to normal permanent teeth. Eruption of primary teeth was normal, whereas all patients had severe eruption problems of permanent teeth. It was hypothesized that the dental lamina for both primary and permanent dentition is normal, but does not resolve completely and therefore may form supernumerary teeth. Abnormalities of tooth morphology is related to inadequate space and arrested eruption. Delayed or arrested eruption is probably caused by diminished resorption of bone and of primary teeth and to the presence of multiple supernumerary teeth.     

Supernumerary teeth in the primary dentition: a report of two cases

Supernumerary teeth occur frequently in the permanent dentition, but they are rare in the primary dentition. Mesiodens is a supernumerary tooth with a cone shaped crown and a short root. The supernumerary tooth which bears resemblance to the tooth with which it is associated is called a supplemental tooth. The etiology of supernumerary teeth is still unknown and not well understood. Radiographic examination of pre-school children is essential for their diagnosis. Early removal of these teeth is required so that complications such as delay in eruption of permanent teeth, crowding, diastema, rotations and certain pathologic conditions can be averted.     

RUNX2 mutations in cleidocranial dysplasia patients

Objective:  Mutations in the RUNX2 gene, a master regulator of bone formation, have been identified in cleidocranial dysplasia (CCD) patients. CCD is a rare autosomal-dominant disease characterized by the delayed closure of cranial sutures, defects in clavicle formation, and supernumerary teeth. The purposes of this study were to identify genetic causes of two CCD nuclear families and to report their clinical phenotypes.
Materials and methods:  We identified two CCD nuclear families and performed mutational analyses to clarify the underlying molecular genetic etiology.
Results:  Mutational analysis revealed a novel nonsense mutation (c.273T>A, p.L93X) in family 1 and a de novo missense one (c.673C>T, p.R225W) in family 2. Individuals with a nonsense mutation showed maxillary hypoplasia, delayed eruption, multiple supernumerary teeth, and normal stature. In contrast, an individual with a de novo missense mutation in the Runt domain showed only one supernumerary tooth and short stature.
Conclusions:  Mutational and phenotypic analyses showed that the severity of mutations on the skeletal system may not necessarily correlate with that of the disruption of tooth development.     

Impaction of mandibular molar by supernumerary tooth: case report

The occurrence of supernumerary teeth in the lower molar region is rare. A prevalence of less than 2% of cases occurring in this region has been estimated. The aim of this study was to present a clinical case of a 7-year-old female patient who had a supernumerary tubercular tooth between the distal root of the primary mandibular left second molar and the impacted permanent mandibular left first molar. Treatment consisted of surgical removal of the supernumerary tooth and case follow-up until the permanent molar's eruption, which occurred in 13 months. This study emphasizes the importance of: early diagnosis, appropriate intervention, and recommended preservation. Thus, it is possible to prevent or reduce complications, simplifying the case outcome.     

Characterization of dental phenotype in patients with cleidocranial dysplasia using longitudinal data

Objective:To investigate the characteristics of the dental phenotype in patients with cleidocranial dysplasia (CCD) using longitudinal data.Materials and Methods:Twelve unrelated Korean CCD patients were observed using a longitudinal series of radiographs and clinical photographs. Statistical analysis was performed on the dental phenotypic data.Results:Although dysplasia of the clavicles, open fontanelle, and wormian bone were observed in all 12 patients, delayed fusion of the mandibular symphysis was found in four patients. One patient did not have a supernumerary tooth (ST). However, 62 STs were found in 11 patients (mean, 5.6 per patient; range of ST emergence, 5 years 6 months–14 years 8 months; developing position, occlusal to the permanent incisors, canines, and premolars and distal and apical to the permanent molars). The mandibular premolar region was the most frequent area of ST development (50.0%, P < .001). All 12 patients showed impacted permanent teeth (IPT), including one patient without ST (mean, 17.8 per patient). Impaction occurred most frequently in the mandibular premolar region and least frequently in the maxillary molar region (93.8% vs 39.6%, P < .01). The ratio of spontaneous eruption of IPT after removal of retained deciduous teeth and/or ST was highest for the maxillary and mandibular incisors (all 54.6%) and lowest for the mandibular canines and premolars (26.7% and 28.9%, respectively); however, the difference was not significant.Conclusions:The emergence time and development position of ST and the root development of IPT should be considered to determine the timing for the removal of ST and forced eruption of IPT.     

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.     

Mesiodens in the primary dentition--a case report

Supernumerary teeth are among the most significant dental anomalies affecting the primary and the permanent dentitions. Mesiodens is a supernumerary tooth with a cone shaped crown and a short root. Though it occurs frequently in the permanent dentition, it is extremely rare in the primary dentition. The exact etiology is still obscure and not well understood. Supernumerary teeth occur as isolated dental findings or as part of a syndrome. The frequency with which supernumerary teeth occur and the effects they have on development of normal occlusion justify the radiographic examination of preschool children. Early removal of such teeth is recommended if they impede the eruption of adjacent permanent teeth, appear inverted or rudimentary, associated with certain pathologic conditions or are symptomatic.     

Il trattamento chirurgico di elementi dentari soprannumerari: tre casi di quarti molari

ObjectivesTo review the diagnosis, causes, treatment, and possible complications of impacted supernumerary fourth molars on the basis of data reported in the literature and our own clinical experience.Materials and methodsWe report three cases of supernumerary fourth molars that were treated by surgical extraction.Results and conclusionsNone of the patients who underwent surgery experienced intraoperative- or postoperative complications. Surgical extraction of the supernumerary tooth eliminates the risk of complications such as root resorption involving adjacent teeth, delayed eruption of permanent teeth, dental crowding, and the development of odontogenic cysts.