Soft tissue ossification and condylar cartilage degeneration following TMJ disc perforation in a rabbit pilot study.

OBJECTIVE: There are limited clinical treatments for temporomandibular joint (TMJ) pathologies, including degenerative disease, disc perforation and heterotopic ossification (HO). One barrier hindering the development of new therapies is that animal models recapitulating TMJ diseases are poorly established. The objective of this study was to develop an animal model for TMJ cartilage degeneration and disc pathology, including disc perforation and soft tissue HO. METHODS: New Zealand white rabbits (n = 9 rabbits) underwent unilateral TMJ disc perforation surgery and sham surgery on the contralateral side. A 2.5 mm defect was created using a punch biopsy in rabbit TMJ disc. The TMJ condyles and discs were evaluated macroscopically and histologically after 4, 8 and 12 weeks. Condyles were blindly scored by four independent observers using OARSI recommendations for macroscopic and histopathological scoring of osteoarthritis (OA) in rabbit tissues. RESULTS: Histological evidence of TMJ condylar cartilage degeneration was apparent in experimental condyles following disc perforation relative to sham controls after 4 and 8 weeks, including surface fissures and loss of Safranin O staining. At 12 weeks, OARSI scores indicated experimental condylar cartilage erosion into the subchondral bone. Most strikingly, HO occurred within the TMJ disc upon perforation injury in six rabbits after 8 and 12 weeks. CONCLUSION: We report for the first time a rabbit TMJ injury model that demonstrates condylar cartilage degeneration and disc ossification, which is indispensible for testing the efficacy of potential TMJ therapies.

Long-term outcome of primary non-surgical root canal treatment.

AIM: The aim of this study is to examine the survival distributions of primary root canal treatment using interval-censored data and to assess the factors affecting the outcome of primary root canal treatment, in terms of periapical healing and tooth survival. MATERIALS AND METHODS: About one tenth of primary root canal treatment performed between January 1981 and December 1994 in a dental teaching hospital were systematically sampled for inclusion in this study. Information about the patients' personal particulars, medical history, pre-operative status, treatment details, and previous review status of the treated teeth, were obtained from dental records. Patients were recalled for examination clinically and radiographically. Treatment outcomes were categorized according to the status for periapical healing and tooth survival. The event time was interval-censored and subjected to survival analysis using the Weibull accelerated failure time model. RESULTS: A total of 889 teeth were suitable for analysis. Survival curves of both outcome measures (periapical healing and tooth survival) declined in a non-linear fashion with time. Median survival of the treated teeth was 119 months (periapical healing) and 252 months (tooth survival). Age, tooth type, pre-operative periapical status, occlusion, type of final restoration, and condition of the tooth/restoration margin were significant factors affecting both periapical healing and tooth survival. Apical extent and homogeneity of root canal fillings had a significant impact towards periapical healing (p < 0.05), but not tooth survival. CONCLUSION: The longevity of treated teeth based on tooth survival was considerably greater than that of periapical healing. Both outcome measures were affected by a number of socio-demographic, pre-, intra-, and post-operative factors. CLINICAL RELEVANCE: Root canal-treated teeth may continue to function for a considerable period of time even though there may be radiographic periapical lesion present. Decision for extraction may be due to reasons other than a failure of the periapical tissues to heal.

High incidence of respiratory infections in 'nil by mouth' tube-fed acute ischemic stroke patients.

BACKGROUND: Respiratory infections are common in acute stroke. Previous studies have found dysphagia is associated with respiratory infections. Of interest is whether patients who are 'Nil by Mouth' (NBM) and tube fed have higher risk of developing infections due to aspiration of bacteria-laden saliva or refluxed material than stroke patients who are fed orally. METHODS: Prospective cohort of 330 ischemic stroke survivors were followed for 30 days and infections recorded. RESULTS: 115 infections were treated with antibiotics; these included 51 respiratory infections. Incidence of infection in NBM tube-fed stroke patients (n = 74) was 69%, with 30 respiratory infections occurring in 74 patients who received enteral feeding after stroke. Logistic regression analysis showed tube feeding during admission was a significant risk for respiratory infection. We also saw a significant time-to-event effect with 73% (22/30) respiratory infections in tube-fed survivors diagnosed on days 2-4 after stroke, and 76% (39/51) of infections in all tube-fed survivors occurring by day 7 after stroke. Relevance to a theory of critical period of susceptibility to infection in acute stroke is discussed. CONCLUSIONS: NBM tube-fed survivors were unlikely to have aspirated anything other than saliva/secretions or reflux, yet experienced significantly higher rates of respiratory infections than survivors fed orally. Stringent oral care and measures to prevent reflux are potentially modifiable aspects of stroke management.

Effects of nonadherent dressing materials on the healing of open wounds in dogs.

Four types of nonadherent dressing materials (rayon/polyethylene dressing, cotton nonadherent film dressings, fine mesh gauze petrolatum dressings, and commercial petrolatum emulsion dressings) were applied on small full-thickness skin defects on the backs of 12 Beagles. At 7 days, the wounds treated with the petrolatum-containing dressings had more contraction than wounds dressed with cotton nonadherent film dressings and wounds dressed with rayon/polyethylene dressings. However, by days 14 and 21, there was little difference in the amount of contraction of any of the wounds. At 7, 14, and 21 days, the wounds dressed with petrolatum-containing dressings had less epithelialization than wounds dressed with cotton nonadherent film dressings and rayon/polyethylene dressings. The uniform open mesh of the commercial petrolatum emulsion dressings allowed the best absorption of exudate and bacteria into the secondary overlying bandage.