Pulp changes in deciduous teeth associated with deep carious dentine.

Serial sections of carious deciduous molar teeth were examined and it was found that inflammation of the pulp occurred when the average thickness of remaining dentine between the most deeply penetrating bacteria and the pulp was 0·6 mm, and the maximal width of dentine between the pulp and the most deeply penetrating bacteria associated with pulpitis was 1·8 mm. The comparable figures for permanent teeth noted by Shovelton (1968) were 0·3 mm and 0·8 mm. This indicates that the deciduous pulp responds more rapidly to the effects of dentine caries than does the permanent tooth, and emphasizes the value of preventing caries of deciduous teeth or at least providing early restorative care.     

Inherited craniofacial fibrous dysplasia

Craniofacial fibrous dysplasia occurring in a mother and two of her three daughters is reported. In all three patients, the condition was characterized by extensive bilateral and bimaxillary involvement. All patients exhibited radiographic evidence of abnormal maxillary and mandibular bone and tooth displacement. Morphologic examination of deciduous teeth from the daughters showed replacement of normal pulp tissue by fibro-osseous lesion. Because of the familial occurrence of the cases, it is proposed that they comprise an example of inherited craniofacial fibrous dysplasia.     

Induction of dentine in amputated pulp of dogs by recombinant human bone morphogenetic proteins-2 and -4 with collagen matrix

Recombinant human bone morphogenetic protein (BMP)-2, BMP-4 and transforming growth factor (TGF)-β₁ combined with collagen matrix as a carrier were examined for their effects on pulp regeneration and dentine formation. Seventy days after implantation of 2 μg of BMP-2, mineralized osteodentine-like tissue containing embedded osteodentinocytes was seen in the cavity. Unmineralized fibrous tissue and pulp-like loose connective tissue were also found in the same cavity. In teeth implanted with 660 ng of BMP-2 only unmineralized fibrous and pulp tissues were seen. In teeth with 220 ng of BMP-2 or collagen alone, pulp tissue was seen. It is therefore likely that the cavity fills with pulp tissue and that spindle-shaped cells elaborate extracellular matrix that mineralizes to be osteodentine in a dose-dependent manner. Similar osteodentine was seen in teeth implanted with 4 μg of BMP-4 and collagen. No distinct tubular dentine was formed, unlike an earlier experiment in which BMP-2 or -4 was implanted with enriched, inactivated dentine matrix. These findings suggest that both BMP-2 and -4 induce osteodentine formation if combined with collagen matrix; some other matrix component present in inactivated dentine matrix might be essential for further differentiation into odontoblasts. In teeth implanted with TGF-β₁, the carrier collagen remained in the cavity and little pulp tissue proliferation was seen, suggesting a possible inhibitory effect of TGF-β₁ in pulp regeneration. It is likely that the response to growth and differentiation factors is dependent on the state of differentiation of pulp cells.     

乳磨牙MTA直接盖髓术后即刻充填的临床观察

目的 评价乳磨牙MTA直接盖髓术后即刻充填临床疗效.方法 用MTA对4～8岁儿童的36颗深龋洞去腐露髓或意外穿髓的乳磨牙进行直接盖髓术后即刻充填治疗,治疗后6个月和2年后随访,观察盖髓后患牙症状、牙髓活力、X线片等疗效指标.结果 MTA治疗36颗乳磨牙,经6个月和2年后随访,其中34颗成功,牙髓活力正常,可见X线片修复性牙本质形成;2颗失败.结论 MTA应用于儿童乳磨牙直接盖髓术是有效的盖髓剂.     

乳牙深龋时冠部牙髓的病理变化和细菌分布

目的 从临床和实验研究两方面探讨深龋乳牙冠髓病理学状况及导致冠髓病变的原因。方法 随机选择Ｈｅ面深龋乳磨牙４５颗,行活髓切断术,光镜下观察其冠髓病理改变;用需氧、厌氧培养技术研究其髓腔内细胞;用扫描电镜观察窝洞底部牙本质小管中细菌的种类和分布特征。结果 ７７．８％的冠髓有不同程度的慢性炎症或慢性牙髓炎急性发作;９４．９％的髓腔中有需、厌氧菌混合感染;洞底牙本质小管中有球菌和杆菌侵入,球菌均位于小管     

The development of the human interradicular dentine as revealed by tetracycline-labelling

The pattern of labelling of the interradicular dentine that forms the floor of the pulp chamber was studied in human deciduous second mandibular molars from patients who had undergone treatment with tetracycline during the period of formation of those teeth. Six teeth exhibited isolated mineralization centres for the interradicular dentine, indicating that this region in man, unlike in rodents, does not develop as a direct continuation of coronal dentine.     

Pattern of transmission of laser light through carious molar teeth

AIMS: The aims of this study were to investigate the pattern of transmission of laser light through carious human molar teeth, and to examine the effect on light transmission of reactions to caries in the dentine. METHODOLOGY: Sectioned carious human molars were examined whilst illuminated from their external surfaces by a helium-neon laser probe of 0.5 mm diameter. The pattern of light transmission was observed and selected specimens were photographed. The passage of light through the surrounding dentine toward the pulp space was investigated by confocal microscopy. Further carious and restored teeth were illuminated from three buccal and three lingual sites to establish the probability of light being able to reach the coronal pulp space. RESULTS: For all 31 teeth examined, it was possible to illuminate the pulp space from a position on the buccal side. The presence of intracoronal restorations did not necessarily prevent light transmission to the pulp. Confocal microscopy demonstrated conduction of light within dystrophic deposits of irregular secondary dentine. CONCLUSIONS: The presence of carious lesions or restorations in molar teeth does not necessarily interfere with transmission of laser light to the pulp space. Light is conducted within irregular secondary dentine. With appropriate probe placement, assessments of pulp health in diseased posterior teeth may be possible using laser Doppler flowmetry.     

A morphometric analysis of the cross-sectional area of dentine occupied by dentinal tubules in human third molar teeth

The number and the mean percentage tubular cross-sectional area of dentinal tubules per square millimetre were calculated in specimens of coronal dentine of 13 intact human third molar teeth from patients 18 to 28 years of age. The dentine was fractured at various known distances from the dentino-enamel junction. Near the dentino-enamel junction the number of tubules per square millimetre was 22 000 and the mean tubular cross-sectional area was 3.6%. Midway between the pulpal wall and the dentino-enamel junction the number of tubules was 37000 mm^?2 and the mean tubular cross-sectional area was 6.2%. Close to the pulp the number of dentinai tubules was 48000 mm^?2 and the mean cross sectional area of tubules was 10.2 percent. The number of tubules per square millimetre more than doubled and the area occupied by tubules increased threefold from the dentine close to the dentine -enamel junction, to that close to the pulp. These differences in tubular patterns at different depths in dentine are clinically significant in dentine permeability, the treatment of traumatized teeth, and pain transmission in dentine.     

A (3H)-proline autoradiographic study of dentine bridge formation in transplanted mouse molar teeth.

A dentine bridge invariably forms across the cervical pulp of transplanted mouse molar isografts. Autoradiographic study demonstrated that bridge formation occurred in two phases. Firstly during post-operative degeneration cellular dentine was formed by non-polar secretion from degenerating cells. Cellular dentine formation was also observed in allografts. Secondly, as isografts recovered, tubular secondary dentine was formed by cuboid pre-odonto-blasts and then by fully differentiated odontoblasts. Similarities were noted between reparative dentinogenesis in transplanted teeth and in teeth in situ. These similarities suggest that reparative dentinogenesis is an identical process irrespective of the stimulus for formation and that the capacity for repair of transplanted teeth resides within the donor tissue. These experiments also demonstrate the remarkable inherent healing capacity of the dental pulp.     

The ultrastructure of the dental tissues in dentinogenesis imperfecta in man

Eight primary incisors obtained from a child with dentinogenesis imperfecta (DI) type II were examined histologically using light microscopy and scanning electron microscopy. In both the DI and control teeth, large dentinal canals were observed along the midline of the crown distributed mesial-distally and coursing towards the pulp. Variably-structured mantle dentine was seen in the DI teeth ranging from tubular to virtually atubular. Enamel separation occurred at the dentine-enamel junction despite apparently normal scalloping. In the enamel, fractures occurred along accentuated striae of Retzius where ultrastructurally there was prism bending and discontinuity. The structure of DI teeth probably results from a structural or regulatory protein abnormality and irregular epithelial-mesenchymal interaction. The combined influence of these factors appears to cause variable histologic appearances and rates of tissue deposition.     

Dentinal dysplasia type I: report of a case

A case of dentinal dysplasia type I is presented. This rare hereditary disturbance of dentine is characterized by short-rooted teeth with sharp conical apical constrictions, aberrant growth of dentine in the pulp chamber leading to reduced pulp space in permanent teeth and total pulpal obliteration in the primary dentition. Clinical, radiographic and histopathological material from a 7-year-old boy, showing the typical features of this disorder in which teeth are prematurely lost through periapical abscesses, cysts or spontaneous exfoliation, is described. A review of the theories of pathogenesis of this condition is included. Management of patients with dentinal dysplasia is difficult and a discussion of the shortcomings of various treatment strategies, including conventional endodontic therapy, periapical curettage and retrograde root filling, and a preventive regimen, are discussed.
  In this case, despite diagnosis being made at an early age and the provision of regular dental care, the patient is now losing teeth because of spontaneous abscess formation.     

Effect of calcium hydroxide treated dentine on pulpal responses

Summary. The purpose of the present study was to test the hypotheses that calcium hydroxide enhances pulpal protection against irritating substances in and around dental restorations when topically applied to cut dentine, and to acquire further information regarding the possible mechanisms involved. Cavities in dentine were treated for 30 days with either a water slurry of calcium hydroxide or a hard-setting calcium hydroxide containing base. Control cavities were treated with saline. The additional effect of dry cutting prior to the restoration was also included as a control. Pulpal responses after placement of a silicate cement restoration were evaluated after an additional period of 30 or 150 days. From histological sections the volumes of inflamed pulp and the volumes of irregular secondary dentine were calculated with a morphometric method of evaluation. Changes in dentine to the calcium hydroxide treatment were observed with scanning electron microscopy. Most pulps in teeth with cavities treated with saline and restored for 30 days with silicate cement exhibited inflammatory alterations. Calcium hydroxide treated teeth had a significantly lower volume of inflamed pulp compared with the saline controls. Dry preparation was also associated with reduced inflammatory reaction. Pulps in teeth with dentine treated by the calcium hydroxide containing hard- setting base displayed the same magnitude of pulpal inflammation as the saline treated controls. After restoration for 150 days the volumes of inflamed pulp tissue were reduced in all treatment groups, however the least pulpal responses were found in teeth treated with calcium hydroxide slurry. Data also showed that the calcium hydroxide treatment was associated with only small volumes of irregular secondary dentine, while in contrast dry cut teeth showed large volumes of irregular secondary dentine. Scanning electron microscopic evaluation of dentine treated with calcium hydroxide revealed reticular structures inside the dentinal tubules     

Diagnosis and management of unusual dental abscesses in children

Although the majority of dental abscesses in children originate from dental caries or trauma, a few are associated with unusual conditions which challenge diagnosis and management. Recent research findings have shed light on these unusual entities and greatly improved understanding of their clinical implications. These conditions include developmental abnormalities such as dens invaginatus in which there is an invagination of dental tissues into the pulp chamber and dens evaginatus in which a tubercle containing pulp is found on the external surface of a tooth crown. In addition, inherited conditions which show abnormal dentine such as dentine dysplasia, dentinogenesis imperfecta, and osteogenesis imperfecta predispose the dentition to abscess formation. Furthermore, 'spontaneous' dental abscesses are frequently encountered in familial hypophosphataemia, also known as vitamin D-resistant rickets, in which there is hypomineralization of dentine and enlargement of the pulp. In addition to developmental conditions, there are also acquired conditions which may cause unusual dental abscesses. These include pre-eruptive intracoronal resorption which was previously known as 'pre-eruptive caries' or the 'fluoride bomb'. In addition, some undiagnosed infections associated with developing teeth are now thought to be the mandibular infected buccal cysts which originate from infection of the developing dental follicles. In the present paper, these relatively unknown entities which cause unusual abscesses in children are reviewed with the aim of updating the general practitioner in their diagnosis and management.     

An electron microprobe study of fluorine in deciduous and permanent incisor tooth crowns at different stages of development in the dog.

Sections of the incisors of sibling dogs were subjected to electron microprobe analysis from the enamel edge to pulp dentine edge from birth to 132 days. Uniformly detectable levels across the deciduous sections at birth decreased to below detectability up to weaning. After weaning, F peaks emerged at pulp and enamel edges. F levels in deciduous and permanent, unerupted and erupted sections were compared and discussed in relation to their natural systemic and topical exposure to F. It is concluded that F reaches the enamel by both routes in erupted teeth.     

Age‐related morphological,histological and functional changes in teeth

Throughout lifetime, the teeth are continuously exposed to numerous chemical and physical impacts, which cause the wear of the dental hard tissues, gingival recession and other oral changes with sometimes subsequent problems. Age‐related wear of tooth surfaces reduces the dental enamel thickness and exposes deeper layers of enamel, which have different physical and chemical properties than the surface enamel. Gingival recession is the main causal factor of root caries and dentine hypersensitivity. Age‐related changes in dentine include the formation of secondary dentine and the reduction in tubular lumen diameter (dentine sclerosis), which lead to a reduction in the volume of the pulp chamber. In addition to the reduction in the volume of pulp chamber, changes to the dental pulp also include dental pulp calcifications. The age‐related physiological changes to the teeth should be carefully distinguished from pathological changes, especially when they induce pain or a negative impact on the oral health‐related quality of life (OHRQoL) of the older individuals. Therefore, regular oral examinations coupled with early preventive measures should aim at maintaining oral health until old age.     

Dentinal dysplasia type 1: A 3D micro‐computed tomographic study of enamel,dentine and root canal morphology

Dentine dysplasia type 1 is a rare and complex dental anomaly. Our aim was to conduct a morphometric assessment of a dentinal dysplasia type 1c (DD1c) caries‐free mandibular second molar, extracted due to symptomatic apical periodontitis. Controls consisted of five intact mandibular second molars. Micro‐computed tomography analysis showed that the DD1c volume % for enamel, dentine/cementum and pulp chamber fell in the 0.36th, 99.97th and 0.09th percentiles of the control teeth (P < 0.01). It also revealed an extremely complicated root canal system in the DD1c tooth with a varying degree of dentine mineralisation and aberrant dentine deposition in the pulp chamber. A crack extending from the external tooth surface to the pulp chamber was identified as a potential site for microbial invasion. Clinical implications include preventive measures and early intervention in reversible pulpitis. Conclusion: Micro‐CT imaging can be useful in establishing post‐extraction diagnosis of cracks and phenomic characterisation of tooth anomalies.     

Endodontic therapy on a dentition exhibiting multiple periapical radiolucencies associated with dentinal dysplasia Type 1

Dentinal dysplasia (DD) Type I, is a hereditary disturbance in dentine formation. In this anomaly, teeth in both primary and secondary dentitions are affected, and radiographically show short and blunted roots with obliterated root canals and periapical pathosis. Management of patients with DD has presented dentists with problems. Extraction has been suggested as a treatment alternative for teeth with pulp necrosis and periapical abscess. Follow-up and routine conservative treatment is another choice of treatment plan in DD. Another approach for the treatment of teeth with DD has included periapical surgery and retrograde filling, which is recommended in the teeth with long roots. The purpose of this report is to present an unusual case of dentinal dysplasia Type I in a 22-year-old woman showing upper and lower teeth with obliterated root canals and periapical radiolucencies. In this case, conventional endodontic treatment was performed. Postoperative radiographs and clinical evaluation demonstrated periapical healing and successful results. Based on the results of this case report, conventional endodontic treatment for cases with pulp necrosis and periapical radiolucencies in dentinal dysplasia is highly recommended.     

Distribution with age and attrition of peritubular dentine in the crowns of human teeth.

Sections of 37 human canine teeth, 7 unerupted, cut transversely at 3 levels occlusal to the pulp, were microradiographed; tubules were counted in groups according to the degrees of tubule closure. In unerupted teeth, there was no consistent variation with age in the numbers of the 4 types of tubule at any level of section, or between the levels of single teeth. With attrition scores 0, 2 and 3, peritubular dentine increased progressively with age, a pattern less evident with attrition score 1. When attrition and age were controlled statistically, tubule closure decreased markedly from outer to inner levels and open tubule counts increased markedly in the same direction. Volume fraction analysis on sections from an intermediate level showed that peritubular dentine increased markedly with attrition, and the tubular lumen reduced reciprocally. The amount of intertubular dentine remained constant. Kendall partial rank correlation coefficients showed a closer relationship between attrition and tubule closure than between age and tubule closure in erupted teeth.     

Micro-tensile bond strengths of bonding agents to pulpal floor dentine

AIM: The purpose of this study was to characterize the dentine surface of the pulpal floor and to determine the micro-tensile bond strengths of two dentine adhesive systems used in conjunction with a resin composite core material to pulpal floor dentine. METHODOLOGY: Thirty-six extracted human molars were cut horizontally with a slow-speed diamond saw to expose the pulp chamber and the pulp tissue was removed. Eight teeth were used to investigate characteristics of untreated and etched dentine surfaces of the pulpal floor using SEM. Twenty-eight teeth were randomly allocated to two groups, each of 14 teeth. In group 1, a 'one-bottle' system (Prime & Bond NT) was used as dentine bonding agent and in group 2, a self-etching-priming system (Clearfil SE Bond) was applied. Pulp chambers of both groups were then filled with resin composite core buildup (FluoroCore) and kept moist in tap water at 37 degrees C for 24 h. Samples were prepared for micro-tensile bond testing by sectioning each tooth vertically in the mid-pulpal floor region and shaped to an hour-glass form of 1 +/- 0.2 mm(2) area at the bonded interface. Micro-tensile bond strengths were determined using a universal testing machine at a crosshead speed of 1 mm min-1. Fractured surfaces were examined by SEM. RESULTS: The intact pulpal floor showed numerous calcospherites with variable tubule density and few accessory canals. Etching the pulpal floor with 34% phosphoric acid gel resulted in an irregular surface with patent dentinal tubules and the dome-shaped calcospherites mostly lost. With self-etching primer, the superficial dentine surface was less demineralized and little peritubular dentine matrix was removed. Mean bond strength for the self-etching-priming (Clearfil SE Bond) specimens was significantly greater than for 'one-bottle' (Prime & Bond NT) specimens (P< 0.05, Student's t-test). The fracture mode of Clearfil SE Bond specimens was mostly partial cohesive failure within dentine, whilst Prime & Bond NT specimens mostly showed partial cohesive failure in bonding resin/composite. CONCLUSIONS: Despite an irregular surface morphology and absence of a smear layer, bonding to pulpal floor dentine was weaker than previously reported for cut coronal dentine. The self-etching-priming system bonded more strongly than the 'one-bottle' system.     

Multiple pulp stones and shortened roots of unknown etiology

An unusual case of generalised pulpal calcifications (pulp stones) with normal clinical crowns is reported in a 13-year-old boy. Radiographic examination revealed pulp stones in the single rooted and premolar teeth, situated at the midroot level, with the roots bulging around them. The apical portion of the roots, periodontal ligament space, and surrounding bone had a normal radiographic appearance, apart from the upper premolars, and no periapical pathology was discernible. The upper premolars exhibited considerably shortened roots. No medical, dental, or family history was found to be contributory. Reviewing the literature revealed similar cases, but with differing diagnoses including dentine dysplasia (DD) or idiopathic cases. This report suggests either a variation of DD or possibly a new nonsyndromic dentine defect, and highlights the difficulties in establishing a definitive diagnosis by traditional methods. The recent discovery that mutation of the bicistronic dentine sialophosphoprotein gene (DSPP) is involved in DD may provide solutions to this problem.