Identification of two novel mutations in keratin 13 as the cause of white sponge naevus

BACKGROUND: White sponge naevus (WSN) is a rare autosomal dominant condition which is characterised by benign, white spongy plaques (oral leukokeratoses) affecting non-cornifying, wet mucosa. WSN shares several ultrastructural characteristics (eg, epithelial thickening, acanthosis, keratin filament aggregation) with a number of epithelial disorders caused by mutations in keratin genes and to-date two mutations, one in each of the mucosal specific keratins, K4 and K13, have been identified as the molecular basis of the disorder. OBJECTIVES: To identify the molecular basis of WSN in two families with a history of the disease. RESULTS: Two novel mutations were identified in helix initiation motif of K13. A T-to-C transition was found in the affected members of one family which is predicted to change leucine115 to proline. In the second family, a similar T-to-C transition was found in codon 108 which is predicted to change methionine to threonine in the protein sequence. These changes were not found in 50 unrelated, unaffected individuals. CONCLUSIONS: The mutations in the helix initiation motif of K13 are the cause of WSN in these families. These cases confirm mutations in the mucosal specific keratins as a significant cause of the disorder.     

The in vitro effects of cetyltrimethylammonium naproxenate on oral and pharyngeal microorganisms of various ecological niches

The purpose of this study was to determine the in vitro susceptibility to cetyltrimethylammonium naproxenate for various aerobic and anaerobic micro-organisms responsible for oral and pharyngeal diseases by assessing the minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) or minimum fungicidal concentrations (MFCs) and by determining kill-times. The MICs of cetyltrimethylammonium naproxenate for 46 tested strains (25 reference strains and 21 clinical isolates) ranged from 8 to 500 micrograms/ml. The MIC was found to be 31.25 micrograms/ml for 36% of the reference strains. Even lower MIC values (15.63 micrograms/ml) were observed for some anaerobic strains, for Haemophilus influenzae and for Candida tropicalis. MIC and MBC values corresponded for the majority of strains tested while the MFC for C. tropicalis and C. albicans was much higher. Only 9.5% of the clinical isolates gave a MIC value of 31.25 micrograms/ml. Enterococcus faecalis, Streptococcus pyogenes and Staphylococcus aureus showed MIC at 62.5 micrograms/ml. The MIC and MBC values among the isolates were comparable, while the MFC value for the yeasts was greater. A concentration of 125 micrograms/ml of cetyltrimethylammonium naproxenate inhibited the growth of all bacteria, except Enterobacteriaceae and Pseudomonaceae, and yeasts. Cetyltrimethylammonium naproxenate shows very rapid kill-time for S. sanguis (0"), and rapid (15") for S. pyogenes, S. dysgalactiae and S. mutans and for Moraxella catarrhalis, while a longer kill-time was necessary for the other microbes tested.     

Use of an orthopaedic fixator for external fixation of the mandible

A patient presented with a chronically infected, non-united fracture of the mandible, with considerable bone loss. He was treated with a metacarpal fixator, the miniPennig external fixator. The fixator is stable and smaller than conventional mandibular fixators. It can be applied and removed under local anaesthesia, if necessary, requires little maintenance and produces minimal scarring. The successful outcome in this patient is encouraging and we commend the use of the fixator in similar difficult cases.     

The correlation between neovascularization and bone formation in the condyle during forward mandibular positioning

The aim of the present study was to investigate the temporal pattern of expression of VEGF (Vascular Endothelial Growth Factor) and new bone formation in the condyle during forward mandibular positioning. The importance of vascularization during endochondral ossification was investigated during natural growth of the condyle and compared to that after forward mandibular positioning. The goal was to further our understanding of the cellular responses during functional appliance therapy with a view to extending the experiment into maturity. One hundred and fifty 35 days old Sprague-Dawley rats, 100 fitted with a bite-jumping appliance and 50 untreated, were divided into 10 groups. One group was sacrificed on each of experimental days 3, 7, 14, 21, 30, 33, 37, 44, 51 and 60 respectively. Sagittal sections were cut and stained with VEGF antibodies and Periodic acid and Schiff's reagent (PAS). Each section was quantitatively analyzed with a computer assisted analyzing program and the temporal sequence of expression of VEGF and new bone formation during natural growth and after mandibular forward positioning was compared. There was significant increase in both vascularization and mandibular bone growth upon forward mandibular positioning and the highest amount of both were expressed in the posterior region of the condyle. The highest acceleration of vascularization preceded that of new bone formation. Thus, forward mandibular positioning was found to solicit a sequence of cellular events leading to increased vascularization and subsequently new bone formation resulting in enhanced condylar growth.     

Parents' self-reported compliance with preventive practices after witnessing their child undergo intravenous sedation for dental treatment

The purpose of this study was to evaluate the self-reported compliance of parents with preventive dental care measures after witnessing their child undergo full-mouth rehabilitation under i.v. sedation. Records of 251 pediatric patients who underwent full-mouth rehabilitation under i.v. sedation between 1995 and 1999 at the University Children's Dental Center in Los Angeles, California were evaluated. Demographic data and rates of post sedation follow-up preventive visits were collected. In addition, seventy-five parents participated in a telephone interview and answered five multiple-choice questions that focused on the following areas: nursing habits, diet, hygiene, and follow-up preventive visits pre and post sedation. Parental attitude towards the experience was also assessed. Only 47 percent of the patients returned for at least one post-op/recall visit at the Children's Dental Center. Seventy-six percent of parents interviewed stated they made improvements in their child's hygiene post sedation. Only 45 percent of parents stated they made improvements in their child's diet and only 47 percent stated that they increased their child's dental recall visits post sedation. Eighty-eight percent of parents stated that they would be willing to have their children undergo i.v. sedation again if necessary for dental treatment. Parental presence during a child's dental rehabilitation via i.v. sedation does not change the preventive behaviors of these parents post sedation when compared to results of other studies.     

Compositional analysis of human acquired enamel pellicle by mass spectrometry

Relatively little is known about the formation of the acquired enamel pellicle other than that it involves the selective adsorption of specific proteins from oral fluids. Previous studies on the identification of pellicle components have relied largely on immunological or enzymatic detection and have been hampered by the fact that only minute quantities of pellicle can be removed from tooth surfaces. The present work describes an improved method of harvesting pellicle that combines mechanical and chemical removal; this approach was used to investigate systematically the desorption of in vitro pellicle components with different solutions. Eleven major in vitro pellicle proteins were identified by using a combination of electrophoretic separation and matrix-assisted laser desorption/ionization-reflectron time-of-flight mass spectrometry. A similar analysis of in vivo-formed pellicle revealed the presence of intact statherin, lysozyme, albumin and amylase. Further analysis of in vivo pellicle by liquid chromatography-electrospray ionization mass spectrometry suggested the presence of numerous low molecular-weight fragments of precursor proteins. The protein composition of in vitro whole-salivary pellicle adsorbed to hydroxyapatite and that of in vivo enamel pellicle differed for proline, the result of a reduction in the content of acidic proline-rich proteins in the in vivo samples. Unique features of the oral environment such as enzymatic activities or mineral surface properties may account for these differences between in vivo and in vitro pellicle formation.     

Influence of cigarette filters on the risk of developing oral leukoplakia in a Kenyan population

OBJECTIVE: To determine the influence of cigarette filters and the effect of smoking Kiraiku (home processed, hand rolled tobacco) on the risk of developing oral leukoplakia among cigarette smokers. DESIGN: Case control using population-based study groups in a Kenyan rural community. MATERIALS AND METHODS: 85 cases and 141 controls identified in a cross-section house-to-house screening of subjects aged 15 years and over and matched for sex, age (+/- 3 years) and cluster origin were compared for their use of filter and non-filter cigarettes as well as their history of smoking Kiraiku. RESULTS: The relative risk (RR) of oral leukoplakia was 9.1 (95% confidence intervals (CI) = 4.1-20.2) in smokers of filter cigarettes and 9.8 (95% CI = 2.3-47.0) in smokers of non-filter cigarettes. The RR in the latter compared to the former was 1.1 and was not statistically significant. Regarding the influence of smoking Kiraiku, the RR of this lesion was 29.3 in smokers of both Kiraiku and filter cigarettes and 17.3 in smokers of both Kiraiku and non-filter cigarettes. CONCLUSIONS: There was no statistically significant difference between the influence of filter and non-filter cigarettes on the risk of developing oral leukoplakia. The effect of Kiraiku on the risk of this lesion was stronger in filter than in non-filter cigarettes. However, the confounding effect of tobacco dose response parameters could not be ruled out.     

Determination of lidocaine in dental pulp by high-performance liquid chromatography

The purpose of this study was to develop a method for lidocaine detection in dental pulp by high-performance liquid chromatography. The amounts of lidocaine in dog pulps were quantitated after local injection to evaluate lidocaine recovery from pulp tissue with this technique. Comparison was also made between the amount of lidocaine found in upper and lower canines. The high-performance liquid chromatography system was shown to be a reliable and reproducible tool for lidocaine determination. Lidocaine extraction from the tissue showed recovery of 90%. The amount of lidocaine recovered from the upper canine (0.21 microg/mg) was higher than the lower canine (0.17 microg/mg).