Histopathological features that predict the recurrence of odontogenic keratocysts.

BACKGROUND: Odontogenic keratocysts (OKCs) constitute between 1.8% and 21.5% of odontogenic cysts and are associated with higher propensity to recur than other odontogenic cysts following surgical removal. Previous studies have been performed to identify clinico-pathological predictive factors in relation to such behaviour. The relationship between the presence of hyalinisation and recurrence of the OKC has not been explored. METHODS: A total of 110 OKCs were selected, comprising 53 non-recurrent cases, 50 cases known to subsequently recur and seven syndromic cases. Cases were examined blind, and histological assessment of the epithelial lining, connective tissue capsule and cyst lumen was made. Statistical analysis was completed using Pearson Chi-square, Fisher's exact test and logistic regression analysis. RESULTS: Subepithelial hyalinisation of the underlying connective tissue capsule (P = 0.006) was significantly more common in OKC that recurred. Recurring cysts demonstrating hyalinisation were seen in a younger age group (mean = 40.8 years) than the non-recurrent cysts (mean = 56.4 years). In addition, subepithelial splitting (P = 0.015) and the position of mitotic figures (P = 0.033) were more common in recurring cysts. CONCLUSION: In this case series, several differences were found in relation to histological features of recurring and non-recurring OKCs. There are many factors responsible for the high recurrence rate of OKCs, and the presence of subepithelial hyalinisation may be used as an additional histopathological feature to predict a greater tendency for recurrence.

Oral presentation of malignant mesothelioma.

We report a case of metastatic mesothelioma presenting as an oral metastasis in a 46-year-old patient. The patient presented with 2 polypoid lesions that appeared to be benign on the dorsum of the tongue. Excisional biopsy showed the presence of metastatic carcinoma that on further investigation proved to be mesothelioma. The initial presentation of mesothelioma as an oral metastasis is not previously reported. This article highlights the importance of biopsy and histopathological diagnosis in presumed benign lesions and the role of the general dental practitioner in screening for oral neoplasms.

A comparison between direct and indirect methods available for human bite mark analysis.

Comparison techniques used in bite mark analysis are many and varied, the choice of technique depending largely on personal preference. Until recently, no one technique has been shown to be better than the others, and very little research has been carried out to compare different methods. This study evaluates and compares the accuracy of direct comparisons between suspects' models and bite marks with indirect comparisons in the form of conventional traced overlays of suspects' models or a new method using photocopier-generated overlays. Artificial bite marks in pigskin were made using standardized sets of models and recorded as photographs and fingerprint powder lifts on tape. The bite mark photographs and fingerprint lifts were coded and randomized so that a blind comparison could be made with the models, traced overlays, and photocopier-generated overlays using a modified version of the American Board of Forensic Odontology Scoring (ABFO) System for Bite Marks. It was found that the photocopier-generated overlays were significantly more accurate at matching the correct bite mark to the correct models irrespective of whether the bite mark was recorded photographically or as a fingerprint lift. The photocopier-generated overlays were also found to be more sensitive at matching the correct bite marks to the correct models than the other two methods used. The modified ABFO scoring system was able to discriminate between a correct match and several incorrect matches by awarding a high score to the correct match.

Bone healing following the use of hydroxyapatite or ionomeric bone substitutes alone or combined with a guided bone regeneration technique: an animal study / Reparação óssea após o uso de hidroxiapatita ou substitutivos de osso ionomérico isolado ou combinados com a técnica de regeneração óssea guiada: estudo em animais

The healing of standardized bone defects grafted with either particulate ionomeric or hydroxyapatite bone substitutes was compared in the mandibular ramus of 30 Sprague-Dawley rats. The possible additional response achieved when combining these materials with a guided bone regeneration (GBR) technique was also evaluated. Three groups of 10 animals received either no implant material or ionomeric or hydroxyapatite bone substitute in defects in the right ramus. The left mandibular defects received the same treatment, except that the operation site was covered by a membrane (GBR technique). Half of the animals were sacrificed at 4 and 10 weeks following surgery, and the inflammatory response at the implant site and the amount of new bone formed in the defects were determined histomorphometrically. Defects implanted with ionometric bone substitute exhibited more bone formation (4 weeks = 3.19 ± 0.38 mm², 10 weeks = 5.35 ± 0.26 mm²) than both defects that received no treatment (4 weeks = 0.88 ± 0.35 mm², 10 weeks = 2.1 ± 0.49 mm²), membrane alone (4 weeks = 1.21 ± 0.005 mm² or hydroxyapatite bone substitute (4 weeks = 1.41 ± 0.46 mm², 10 weeks = 3.34 ± 0,41 mm²) at 4 weeks (P<=.01) and at 10 weeks (P<=.05). The use of a GBR technique did not increase the amount of bone formed, compared to the use of bone substitutes alone. Hydroxyapatite and ionomeric bone substitutes used alone were more effective in inducing repair of the defects than was GBR membrane alone. The use of hydroxyapatite was associated with a greater inflammatory reaction (P<=.01) than was ionomer in this model