Regional odontodysplasia: a review of the literature and report of four cases.

Regional odontodysplasia (RO) is a rare dental anomaly involving both dentitions, mostly teeth of one quadrant. The characteristic findings are discolored soft teeth accompanied by gingivitis, swelling or abscess. Enamel and dentin are hypomineralised and hypoplastic, so that the 'ghost teeth' appear shadowy in radiographs with wide pulp chambers. The etiology is unknown. Epidemiological data is rare; 138 cases of RO have been published to date and reports on ultrastructure are few. An analysis of published cases of RO in the international literature is presented. The sex ratio of females to males was 1.7:1. The age at the time of diagnosis ranged between 4 and 23 years. The maxilla was more often affected (maxilla to mandible ratio 1.6:1). In 67 patients the deciduous and permanent dentitions were affected (47.1%). In 129 cases, affected teeth lay side by side. Missing tooth development was observed in 10.7%. Failure of tooth eruption of RO teeth occurred in 39.7%. In addition, four cases with RO which were collected over a period of more than 25 years are presented. Ultrastructural findings of one specimen are demonstrated.

Histocytological evaluation of the reaction of rat pulp tissue to Carisolv.

OBJECTIVES: Carisolv is a viscous substance for the chemo-mechanical removal of caries. The aim of this study was to examine the tissue reactions of pulp and dentin tissue to Carisolv in vivo. METHODS: In 48 caries-free molars (24 Wistar rats, age: 3 months) an occlusal cavity was prepared. The roofs of the pulp chambers were perforated with a sharp probe and Carisolv solution was placed onto the exposed pulp of 24 molars for 1, 10 and 20 min. Twenty-four contralateral molars served as controls and were coated with an inert liquid containing isotonic saline solution, carmellose and erythrosin. RESULTS: After a contact period of 10 and 20 min in the experimental group, pulpal destruction of intercellular substance and cells including odontoblasts was observed up to a depth of 150 microm, in addition to the mechanical damage by perforation (e.g. dentin particles). The pulpal and predentin fibrils as well as the dentin fibrils appeared to be intact and did not differ from the controls. After a contact time of 1 min a weaker damage of pulp cells and odontoblasts, as well as intact fibrils in pulp, predentin and dentin could be observed. CONCLUSIONS: Radicals of Carisolv (OH- and OCI-) cause alkaline hydrolysis of cellular components but do not decompose collagenous tissue components.

Clinical anatomy and palpability of the inferior lateral pterygoid muscle.

STATEMENT OF PROBLEM: The intraoral palpation technique of the inferior belly of the inferior lateral pterygoid (ILP) muscle is a standard diagnostic examination method for temporomandibular joint dysfunction syndrome, although different studies have revealed inconsistent results. PURPOSE: This study assessed the feasibility of the ILP muscle palpation by a simulated clinical setting. MATERIAL AND METHODS: Three dentists performed a bilateral palpation of the ILP muscle in 53 fresh and unfixed human cadavers and decided whether the muscle was palpable or unpalpable. In a second step, it was observed through the dissected infratemporal fossa, whether the examiner's finger did or did not touch the ILP muscle by simulating the performed palpation. Palpatory findings were supplemented by 1-dimensional measurements for determination of topographic relations of the ILP muscle within the infratemporal fossa. For statistical analysis, sensitivity, specificity, and negative and positive predictive values of the palpation technique were calculated. Interexaminer agreement was estimated with the kappa value. RESULTS: In 86 of 106 dissected specimens, a superficial fascicle of the medial pterygoid muscle was found in direct proximity to the ILP muscle. In these cases, a residual distance of 7.8 +/- 3.2 mm remained between the ILP muscle and buccinator fascia indented by the tip of the examiner's finger. In 10 of 20 specimens with an absent superficial fascicle, the finger was able to reach the ILP muscle. CONCLUSION: It is recommended that the ILP muscle palpation technique should no longer be considered as a standard clinical procedure because it is nearly impossible to palpate the ILP muscle anatomically and because the risk of false-positive findings (by palpation of the medial pterygoid muscle) is high.

Periosteally derived osteoblast-like cells differentiate into chondrocytes in suspension culture in agarose.

Pluripotent cells from the periosteal layer adjacent to cortical bone attain an osteoblast-like phenotype in culture when reaching confluence in monolayer. It is unknown whether such newly differentiated osteoblast-like cells preserve the chondrogenic potential characteristics for stem cells derived from the periosteum. Primary osteoprogenitor cells derived from bovine metacarpal periosteum were differentiated into alkaline phosphatase-positive osteoblast-like cells by an established monolayer culture protocol. After transfer into suspension culture in agarose gels, the cells differentiated into chondrocytes demonstrated by the production of collagen II, but not of collagen I, as well as alkaline phosphatase activity was abated. Contrarily, with continuation of monolayer culture, the cells maintained their osteoblast-like phenotype and secreted large amounts of collagen I and a minor quantity of collagen III and V. The alkaline phosphatase activity steadily increased during the entire culture period of 2 weeks. Thus, our culture techniques can serve as useful tools to study mechanisms of differentiation by modulating the phenotypic potential of osteogenic cells. The results presented here support the notion that the extracellular environment strongly influences the cell type and its metabolism.