Abfraction: separating fact from fiction

Non-carious cervical lesions involve loss of hard tissue and, in some instances, restorative material at the cervical third of the crown and subjacent root surface, through processes unrelated to caries. These non-carious processes may include abrasion, corrosion and possibly abfraction, acting alone or in combination. Abfraction is thought to take place when excessive cyclic, non-axial tooth loading leads to cusp flexure and stress concentration in the vulnerable cervical region of teeth. Such stress is then believed to directly or indirectly contribute to the loss of cervical tooth substance. This article critically reviews the literature for and against the concept of abfraction.
Although there is theoretical evidence in support of abfraction, predominantly from finite element analysis studies, caution is advised when interpreting results of these studies because of their limitations. In fact, there is only a small amount of experimental evidence for abfraction. Clinical studies have shown associations between abfraction lesions, bruxism and occlusal factors, such as premature contacts and wear facets, but these investigations do not confirm causal relationships. Importantly, abfraction lesions have not been reported in pre-contemporary populations.
It is important that oral health professionals understand that abfraction is still a theoretical concept, as it is not backed up by appropriate clinical evidence. It is recommended that destructive, irreversible treatments aimed at treating so-called abfraction lesions, such as occlusal adjustment, be avoided.     

Complications of local anaesthesia. An observational study

Abstract: Objectives: Local anaesthesia is increasingly used by dental hygienists. As little is known about the incidence of adverse effects during and after the administration of local anaesthetics, we evaluated side‐effects associated with local anaesthesia. Methods: A prospective observational study was conducted using standard criteria among a group of 103 patients receiving mandibular block anaesthesia. Results: Physical reactions like clenching fists (14.5%), moaning (12.6%) and turning pale (7.8%) were frequently observed. Patients (3.8%) showed a painful reaction because of needle contact with a nerve or the periosteum. Systemic complications were not observed. After the injection, 41.7% said they felt tense during the administration; 4.9% of the patients reported swallowing problems and 3.9% a tachycardia. Conclusions: These results suggest that administration of local anaesthesia has a small risk of adverse events. Complications, if they occur, seem minor and transient in nature.     

Relationships between blood pressure variability and left ventricular parameters in haemodialysis and renal transplant patients

SUMMARY: Blood pressure (BP) elevation and left ventricular hypertrophy (LVH) are important factors in the high cardiovascular mortality on the renal replacement programme. the relationship between these, predictable in essential hypertension, is less well defined in uraemia. We wished to examine the contribution of abnormal blood pressure variability (BPV) to the cardiovascular changes seen in uraemia and after renal transplantation. Twenty-four hour ambulatory blood pressure monitoring (ABPM), and simultaneous echocardiography, on a cohort of 35 long-term, long-hours haemodialysis survivors and 28 patients with stable renal transplants was undertaken. We also retrospectively compiled biochemical and clinical data. There were strong relationships between both diurnal and standard deviation measures of BPV and left ventricular cavity size and function: per cent fall in awake to asleep diastolic BP with fractional shortening index (FSI), r =0.28, P =0.039; with left ventricular mass index (LVMI), r =−0.35, P =0.011. This study suggests that reduced diurnal and short-term BP variability is cross-sectionally associated with a dilated, heavier left ventricle (LV) with worse systolic function. Thus, BPV may independently contribute to the abnormal LV structure and function commonly seen in uraemia.     

Atypical choristomatous cysts of the orbit

Background: The commonest choristomatous cysts of the orbit are dermoid and epidermoid cysts, which are lined by kerantinizing seuamous epithelium. They typically occur in the superior orbit, most commonly superotemporally. Other types, lined by different epithelia, and other orbital sites are much less common. Methods: Five cases of atypical orbital cystic choristomas that presented over the past 6 years are reported. The clinical and radiological features, surgical approach and findings, and histology are described. Similar cases from the literature are reviewed, and possible aetiology discussed. Results: Four of the cysts were lined by a non-keratinizing epithelium resembling conjunctiva; two had adnexal structures in their walls. Compared with typical dermoid and epidermoid cysts, these ‘conjunctival dermoids’ and ‘conjunctival cysts’ of the orbit tended to present later in life, none were associated with bony defects, and three of the four occurred in the superomedial quadrant. One case occurred inferiorly, a rare site for orbital conjunctival dermoids and cysts, or typical dermoids and epidermoids. The fifth case, also inferior; is an example of a cyst within choristomatous lacrimal tissue. Conclusion: Choristomatous cysts of the orbit may occur with non-keratinizing epithelial linings, and such cysts tend to differ clinically from the commoner dermoids and epidermoids. They may also occur in atypical sites such as the inferior orbit.