Demineralization of dentin with EDTA in organic solvent: immunofluorescence of collagen in osteogenesis imperfecta and normal teeth

Dentine disorders and adhesive treatments: A systematic review

OBJECTIVES

A better understanding of the microstructure and mechanical properties of enamel and dentine may enable practitioners to apply the current adhesive dentistry protocols to clinical cases involving dentine disorders (dentinogenesis imperfecta or dentine dysplasia).

DATA/SOURCES

Publications (up to June 2020) investigating the microstructure of dentine disorders were browsed in a systematic search using the PubMed/Medline, Embase and Cochrane Library electronic databases. Two authors independently selected the studies, extracted the data in accordance with the PRISMA statement, and assessed the risk of bias with the Critical Appraisal Checklist. A Mann-Whitney U test was computed to compare tissues damage related to the two dentine disorders of interest.

STUDY SELECTION

From an initial total of 642 studies, only 37 (n = 164 teeth) were included in the present analysis, among which 18 investigating enamel (n = 70 teeth), 15 the dentine-enamel junction (n = 62 teeth), and 35 dentine (n = 156 teeth). Dentine is damaged in cases of dentinogenesis imperfecta and osteogenesis imperfecta (p = 2.55E-21 and p = 3.99E-21, respectively). These studies highlight a reduction in mineral density, hardness, modulus of elasticity and abnormal microstructure in dentine disorders. The majority of studies report an altered dentine-enamel junction in dentinogenesis imperfecta and in osteogenesis imperfecta (p = 6.26E-09 and p = 0.001, respectively). Interestingly, enamel is also affected in cases of dentinogenesis imperfecta (p = 0.0013), unlike to osteogenesis imperfecta (p = 0.056).

CONCLUSIONS

Taking into account all these observations, only a few clinical principles may be favoured in the case of adhesive cementation: (i) to preserve the residual enamel to enhance bonding, (ii) to sandblast the tooth surfaces to increase roughness, (iii) to choose a universal adhesive and reinforce enamel and dentine by means of infiltrant resins. As these recommendations are mostly based on in vitro studies, future in vivo studies should be conducted to confirm these hypotheses.

Demonstration of type III collagen in the dentin of mice

It has been reported that, although type III collagen is present in human dentin where there is dentinogenesis imperfecta and in reparative dentin, it is absent in normal dentin. In a preliminary study, however, we observed evidence showing that small amounts of fibers showing positive labeling for type III collagen are present in the molars of normal mice. In the present study, in order to localize type III in normal dentin, immunofluorescent and immunoelectron microscopic examinations of the molars of normal mice were carried out using affinity-purified antibodies to mouse type III and type I collagen. The fibers positive for type III collagen were much more frequently observed in the root than in the crown. These fibers ran in peritubular dentin or near that in parallel to them. The incidence of the existence of dentinal tubules associated with type III collagen-positive fibrils either in or near peritubular dentin was low. These fibrils positive for type III collagen showed a clear cross-banding. In dentinal tubules, unusual collagen aggregations, segment long-spacing-like and fibrous long-spacing-like structures which were intensively stained for type I collagen but weakly so for type III collagen were seldom observed. Type III collagen-positive fibers often extended towards the pulp beyond the odontoblast layer, suggesting that these fibers were produced, at least partly, by the pulp cells.

Immunohistochemical localization of types I, V, and VI collagen in human permanent teeth and periodontal ligament

Types I, V, and VI collagen were immunohistochemically localized in frozen and paraffin sections of human permanent teeth, periodontal ligament, and alveolar bone, by means of polyclonal antibodies. Hyaluronidase was effective in exposing epitopes of the various collagen types. The expression of type I collagen in predentin was strong in frozen sections, whereas the dental pulp stained relatively weakly. Staining intensity in the dentin matrix decreased toward enamel and cementum. Reactivity in the periodontal ligament was moderate, and it was weaker in the alveolar bone and also in cementum, which stained more intensely in paraffin sections. Staining for type V collagen was strong in the pulp. Weak reactivity in predentin became uniformly evident in frozen sections only, and dentin was negative. The periodontal ligament stained with moderate intensity, and a weak staining reaction was seen in cementum and bone. Staining for type VI collagen in the pulp and periodontal ligament was strong, whereas predentin and dentin were negative. The alveolar bone stained moderately, and non-uniform reactivity was present in cementum. In non-mineralized dental tissues, the use of frozen material enabled good immunohistochemical localization of the distinct collagen types to be carried out. Their distribution patterns in dental tissues not only differed, but the relative staining intensities for each collagen type in the pulp and predentin were inversely related. However, differences may exist in the exposure of the epitopes of collagen(s) between soft and mineralized tissues.

Benign osteoblastoma of the mandible

Benign osteoblastoma is a rare osteoblastic tumour with osteoid and bone deposition. A rapidly growing osteoblastoma involving the area of the mandibular first and second molar of a 20-year-old female is described. Investigation of the collagenous components of the tumour by immunofluorescence was suggestive of a normal collagen synthesis by the tumour osteoblasts. The lesion is discussed with particular emphasis on its differential diagnosis and matrix constituents.

Contiguous enlarged dental follicles with histologic features resembling the WHO type of odontogenic fibroma

Defective odontogenesis and/or retarded eruption of teeth can be associated with histologic features akin to odontogenic fibroma in the dental follicles. Unerupted mandibular premolar and molar teeth of a 24-year-old man were surgically exposed, yet the teeth failed to erupt. About a year and a half later, radiographs indicated further enlargement of the follicle of the premolar, and both teeth were subsequently surgically removed. Histologically, the follicles were composed of mature collagenous tissue among which epithelial islands and numerous clusters of calcified bodies were present. Indirect immunofluorescence showed positive staining for type I and type III collagen, which exhibited a sparse distribution, but not for the aminoterminal propeptide of type III procollagen. The hamartomatous nature of the lesions is discussed with emphasis on their histologic resemblance to the WHO type of odontogenic fibroma.

Dentin dysplasia type II: absence of type III collagen in dentin

A three-generation family with dentin dysplasia (DD) Type II is presented. Affected family members share common radiologic features with clinically varied expression of tooth discoloration and occlusal wear. Both the primary and the permanent dentition appear to be affected. No generalized connective tissue involvement is found. The mode of inheritance is autosomal dominant. Histologically, the findings are consistent with DD Type II. In indirect immunofluorescence, the irregular radicular dentin of an affected permanent tooth failed to stain with specific antibodies against Type III collagen and the N-terminal propeptide of Type III procollagen.

Maxillary fibrosarcoma with extracellular immuno-characterization

Maxillary fibrosarcoma of a 31-year-old female is described with special reference to immunofluorescent characterization of the extracellular matrix. Following extractions, endodontic treatment and occlusal adjustment the tumour was operated on. The spindle-shaped tumour cells displayed a herring-bone pattern. The tumour was diagnosed as a fibrosarcoma and graded as poorly differentiated. Immunostaining for the specific type I collagen was positive throughout the tumour matrix, whereas staining for type III collagen was faint and occasional, and did not definitely codistribute with reticulin. Staining for type IV collagen and fibronectin in the tumour matrix was negative.

Mandibular dentinoma

Dentinoma is a rare odontogenic tumor showing the inductive effects of odontogenic epithelium on the connective tissue. A case of the tumor occurring in the region of the missing right mandibular second permanent premolar of an 11-year-old male is described. The tumor and the impacted right mandibular second deciduous molar were surgically removed. Histologically, areas of hyalinized collagen, osteodentin and tubular dentin were seen in a stroma varying from mesenchymal to more mature. Immunostaining for the distinct types I, III and IV collagens were negative in the hyalinized areas. Type IV collagen stained as a halo corresponding to the basal membrane zone surrounding the groups of odontogenic epithelial cells. Recovery was uneventful. There was no recurrence of the tumor during the first 10 months of follow-up.