Ultrastructure of fenestrated capillaries in human dental pulps.

Dental pulps of both the primary and permanent dentitions were studied. Fenestrated capillaries were found at varying depths within the odontoblast layer in the root and crown portions of pulps. The fenestrae were in the attenuated part of the endothelial cell cytoplasm away from the nucleus. They averaged 60 nm in diameter and were bridged by a membrane or diaphragm approximately 7 nm thick.     

Effects of injury and inflammation on pulpal and periapical nerves

Several studies dealing with the reactions of dental nerve fibers to injury and inflammation are reviewed in this article. The subgroup of dental nerve fibers that contains calcitonin gene-related peptide (CGRP) was examined by immunocytochemistry at various times (1 to 35 days) after one of three degrees of injury: (a) Mild: Four days after making shallow cavities into cervical dentin of first molars of anesthetized adult rats, we found that CGRP fibers had sprouted into the subjacent odontoblast layer and dentin, and then returned to normal by 3 wk. (b) Intermediate: If the cervical cavities were acid etched, we found damage to the odontoblast layer, microabscess formation, and sprouting of CGRP fibers near the abscess, with subsequent formation of reparative dentin and healing. (c) Severe: If the pulp was exposed, a variety of reactions could occur, the most prevalent of which was a severe necrosis leading to development of periapical lesions. Analysis of the progressive stages of pulpal abscess and necrosis showed sprouting CGRP nerve fibers (a) at the retreating interface between abscess and vital pulp; (b) in periapical areas during onset of lesions; and (c) around chronic abscesses in granulomatous periodontal tissues. These studies are discussed in relation to various dental clinical problems such as hypersensitive teeth, episodic toothache, early onset of periapical lesions, dental anesthesia, and possible roles for sensory fibers and neuropeptides in tissue defense and healing.     

Metal ceramic compatibility: a review of the literature

Metal ceramic restorations are popular in restorative dentistry. Although bonding mechanisms are understood, defining compatibility of alloy and porcelain has been illusive. Chemical compatibility implies a chemical bond between ceramic and alloy that resists stresses resulting from thermal and mechanical incompatibility without compromising esthetics. Research has attempted to predict and test compatibility with varying degrees of success. Despite the success of metal ceramic restorations over the years, compatibility remains undefined without standardized testing procedures. For optimal results, the dentist should communicate with experienced laboratory personnel to meet the specific needs of the patient.     

Micro-electronic monitoring of functional appliance wear

Measurement of actual bionator wear has so far been confined to a few studies involving only small samples. In this study a micro-electronic timing device was used in a greater number of patients (53 children) after the system proved to be reliable in a pretest involving 18 subjects. The patients were 9-14 years of age and had a timing device fitted in their bionators over a period of 3-6 months. The data were read from the memory chip at the regular treatment sessions every 3-4 weeks. There was evidence that the patients averaged 7.65 hours per day of wear, thus fulfilling only 50-60 per cent of the orthodontist's requirements. Further details and implications of the measurements are discussed.     

Oral complications associated with neonatal oral tracheal intubation: a critical review

This paper summarizes and evaluates the oral complications associated with orotracheal intubation in neonates. The palatal defect resulting from orotracheal intubation is best described as palatal grooving, rather than clefting since no oral nasal communication has been demonstrated. Palatal grooving may be caused by the inhibition of the molding tongue forces on the lateral palatine shelves. The incidence of palatal grooving increases with duration of intubation and reportedly resolves following extubation. However, posterior cross-bites, high palatal vaults, and poor speech intelligibility have been reported in children who previously have been intubated. Impingement of an orotracheal tube on the alveolus rather than on the palate may cause alveolar grooving which can cause dilaceration of primary teeth. Bilateral linear enamel hypoplasia in premature neonates is caused by an interruption in amelogenesis from intrauterine disturbances. However, gross unilateral incisal enamel hypoplasia in children who have been intubated is probably due to traumatic intubation. Avoiding excessive pressure on the maxillary alveolus during intubation is suggested. An appliance is available which secures oral tubes and protects the palate and alveolus.     

Development of a tooth germ within an autogenous clavicular graft

The left side of the mandible distal to the second primary molar of a 3 years old Southern Chinese boy was resected as a result of osteomyelitis. A diaphyseal clavicular graft pedicled on the sternomastoid muscle was selected for the reconstruction of the mandible. By the age of 6 years, the mandible although stunted in size did exhibit appropriate remodelling. In addition a tooth germ in the region of the second permanent molar was found developing in the autogenous bone graft of the mandible.     

The presence of bacteria in the oral epithelium in periodontal disease. III. Correlation with Langerhans cells

Langerhans cells (LC) are cell types found in the skin and gingiva. LC have immunological functions as phagocytic cells and as antigen-presenting cells for T and B lymphocytes. Sections from biopsies of the gingiva in cases of periodontal disease were found to have increased numbers of LC. These biopsies also contained intragingival bacteria. Serial sections of frozen specimens of human gingiva were prepared for staining. Hematoxylin and eosin were used for tissue survey, the Gram stain for assessment of bacterial invasion, anti-Leu-6 monoclonal antibody associated with peroxidase technique (PAP) to identify LC, antibacterial sera to Bacteroides gingivalis and Actinobacillus actinomycetemcomitans associated with peroxidase to specifically identify these two common periodontopathogenic bacteria. Additional positive identification of bacteria was performed by preparing the same histological section containing gram-stained particles for scanning electron microscope and transmission electron microscope LC confirmation. The results suggest that the increased number of LC seen in diseased sites of oral epithelium containing intragingival microorganisms may be one of the host immune mechanisms to penetration by bacteria.