Human papillomavirus (HPV) can establish productive infection in dysplastic oral mucosa, but HPV status is poorly predicted by histological features and p16 expression.

AIMS: Previous studies have reported the presence of high-risk human papillomavirus (HR-HPV) in a subset of dysplastic oral epithelial lesions. Many cases show a histological spectrum of atypia similar to that seen in non-human papillomavirus (HPV) severe epithelial dysplasia, but some studies have suggested that HPV status can be inferred on the basis of histological features. We aimed to assess the utility of such histological features and p16 as surrogate markers of HPV infection in a retrospective cohort of 33 cases of severe epithelial dysplasia, with matched clinicopathological data and histological features. METHODS AND RESULTS: Tissue sections were assessed for the expression of p16, minichromosome maintenance 2, HPV E4 and HPV L1 by the use of immunohistochemistry. HPV16/18 E6 and E7 expression was assessed by the use of RNA in-situ hybridisation (RNAScope). In the cohort, 18.2% of cases (6/33) were HR-HPV-positive, with no age/gender differences between the HPV-positive and HPV-negative groups. HPV E4 and HPV L1 were expressed in surface keratinocytes in four of six (66%) HPV-positive cases, indicative of productive HPV infection. Lack of p16 expression was predictive of HPV-negative status, but sensitivity and specificity varied according to the cut-off. Histologically, the presence of karyorrhectic nuclei and abnormal mitotic figures was higher in HPV-positive lesions (P < 0.05), but the predictive specificity and sensitivity were suboptimal (sensitivity, 0.75; specificity, 0.52). CONCLUSIONS: This study demonstrates, for the first time, that a minority of severely dysplastic oral lesions harbour productive, biologically relevant HPV infection. Consideration should be given to the specific assessment of HPV status in severe epithelial dysplasia cases, as both p16 status and the presence of karyorrhectic cells are poor predictive markers of HPV status.

Descriptive study of the longevity of dental implant surgery drills.

BACKGROUND: Atraumatic preparation of the osteotomy site is critical for osseointegration. PURPOSE: This study aimed to investigate the effects of multiple usages of dental implant drills on bone temperature changes and to examine the cutting surfaces of these drills under a scanning electron microscope (SEM). MATERIALS AND METHODS: The implant osteotomy procedure was adapted to the experimental setting to simulate wear on implant drills by preparing bovine ribs using a constant drilling force. Thermocouples were placed in the specimens to record temperature changes. SEM images of the drills were taken, and elemental spectroscopic analysis was performed. RESULTS: Temperatures measured in the bone adjacent to the implant site did not exceed 27.7°C during the experiment. Spectroscopic elemental analysis indicated that two of the drills were of a stainless steel composition, and the other drill consisted of a tungsten carbide-coated stainless steel. The tungsten carbide-coated bur had the lowest overall drilling temperatures and showed the least surface corrosion and plastic deformation. SEM analysis showed degradation of the cutting surfaces of the burs although the plastic deformation and surface wear did not appear to affect the cutting temperatures. Surface corrosion was observed on the cutting surfaces. CONCLUSIONS: Drills used for up to 50 osteotomies do not appear to elevate bone temperatures to a harmful level. However, drill corrosion is potentially important in determining the life span of implant burs.