Periodontal disease: Mechanisms of infection and inflammation and possible impact on miscellaneous systemic diseases and conditions.

Periodontitis is a chronic inflammatory disease, resulting from a predominantly gram-negative microbial infection within the sub-gingival dental plaque biofilm. The resulting inflammatory response in the periodontal tissues may facilitate intravascular dissemination of micro-organisms and their products, throughout the body. The total surface area of this inflammatory field is estimated to be the size of the palm of the hand. A skin lesion of this size would prompt immediate medical intervention. However, the intra-oral (and similar-sized) infection is frequently ignored by health professionals, despite the fact that it may be associated with a range of systemic diseases/conditions.

A study of furcation defects at first permanent molars in African mandibles.

INTRODUCTION: This study was undertaken after a personal clinical observation (by AV) that periodontal disease and subsequent attachment loss in the molar root bi-furcation occurs more frequently on the buccal than the lingual aspect of mandibular permanent molars, particularly the first molar. AIMS: The purpose of this investigation was to determine the prevalence and severity of furcation defects on the buccal and lingual aspects of mandibular first molars visually and photographically. MATERIALS AND METHODS: One hundred and six dried human mandibles with neither caries nor restorations on the second premolar or first and second molars were the study sample. Presence and severity of the furcation defects and the position of the mandibular first molar in the mandibular arch were recorded visually. The mandibles were then photographed using a standardized method and the same observations made and compared with those of the visual recording. RESULTS: There were more furcation defects on the buccal than the lingual aspects. Most first molars were within the arch, followed by buccal then lingual. The lowest prevalence, and severity, of furcation defects was when the first molar was within the mandibular arch. CONCLUSIONS: Mandibular first molar furcation prevalence and severity on the lingual was lower than on the buccal aspect, particularly when the first molar was within the arch suggesting that an "anatomically normal" position of the mandibular first molar may have a protective effect. Another observation was that standardized photographs of the mandible may be used for measurements and provides a convenient data base for research.

Temperature gradients in periodontal pockets.

This study was undertaken to determine whether there is any correlation of temperature within periodontal pockets with their depths. Pocket temperatures were measured with a thermocouple at 1 mm intervals of depth in 247 pockets, in 20 patients with periodontitis, mesiobucally and mesiopalatally/mesiolingually in relation to 6 standard teeth. Pocket temperatures increased consistently with pocket depth. Maxillary pockets were cooler than mandibular pockets, but in both jaws the differences between buccal and palatal/lingual pockets were not statistically significant. The findings are in keeping with knowledge about the increased temperature of inflamed tissues and the study appears to have relevance to the diagnosis of disease activity in pockets, but further studies are necessary to establish reference levels of pocket temperature.

Scientific surface roughness values for resin based materials.

INTRODUCTION: Surface roughness of dental restorative materials is most often established with the Ra value obtained using profilometry or by assessing surface topography with the scanning electron microscope (SEM). Both methods should validate each other in confirming surface roughness. AIMS AND OBJECTIVES: The purpose of this study was to compare surface roughness values obtained with a profilometer to the SEM appearance of 6 resin-based restorative materials and assess whether Ra was appropriate as a sole surface roughness measure. Methods Six 5mm diameter specimen discs of Prodigy (Pr); Z100 (Z); Compoglass F (C); Hytac Aplitip (H); Photac-Fil (Pf) and Vitremer (V) were prepared against Mylar strips and stored in distilled water for 14 days. One side of each disc was sequentially polished with Soflex discs to super fine state, the other side remained unpolished. Three surface roughness measurements were made on each surface (n=18) recording Ra, Rv, Rp and Rt values, this data was subjected to a four way ANOVA and Tukey's Studentised Range Test (p=0.05). Two unpolished and two polished discs per material were prepared for SEM, evaluated and visually grouped for surface roughness. RESULTS: Approximate ascending order of roughness was Z, Pr, H, C, V, Pf for Ra, Rv, Rp and Rt and un/polished treatment. Polishing increases surimens into a "bland" (Pr, H, Z, C) and "textured" group (Pf and V). The polished specimens gave four groups: (Pr), (Z and C), (H) and (V and Pf) of increasing surface complexity. Polishing caused surface scratching, removed the matrix, reduced or removed filler particles and exposed voids within the material. CONCLUSIONS: This study emphasises the importance of using more than one technique to assess surface roughness. Rv and Rp values should be utilised to better understand polish induced surface feature changes. Rv maximum is a better measure to identify surface defects which could affect restoration longevity.

Surface roughness of aesthetic restorative materials: an in vitro comparison.

The purpose of this study was to compare the surface roughness of three types of aesthetic restorative material. Six standard samples of two brands of each type of material were prepared namely: hybrid composites (Prodigy, Z100), compomers (Compoglass F, Hytac Aplitip) and glass ionomer cements (Photac-Fil, Vitremer) in a perspex mould (N = 36). Upper and lower surfaces were covered with Mylar strips which, in turn, were covered with glass slides and compressed to express excess material. After light curing, specimens were stored in distilled water for 14 days. Thereafter, one side of each specimen was polished sequentially with medium, fine and super fine Soflex discs (treatment). Untreated surfaces served as controls. All surfaces were examined with Talysurf and the surface roughness (Ra) of each specimen was recorded. Three measurements were made of each specimen. A 4-way ANOVA and Tukey's Studentised range test were used to analyse the data. Statistically significant effects were found for both type of material (P = 0.0001) and for treatment process (P = 0.0065). Among unpolished specimens: Compoglass F is significantly rougher than Vitremer, Z100, Prodigy and Hytac Aplitip, and compomers are significantly rougher than hybrids. Among polished specimens: Photac-Fil is significantly rougher than Z100 but does not differ from Compoglass F, Vitremer, Prodigy and Hytac Aplitip, and glass ionomers are also significantly rougher than hybrids. The smoothest surface is obtained when curing materials against a Mylar strip.

Bony defects in dried Bantu mandibles.

Forty-three dried South African Bantu mandibles were examined visually and radiographically for the frequencies of occurrence of apical defects, bifurcation involvements, dehiscences, and fenestrations. Statistical evaluation of the data revealed no significant discrepancy between the visual and radiographic findings.

Clinical crown height (length)--a review of published measurements.

BACKGROUND, AIMS: Clinical crown height is an objective measure of the position of the gingival margin which could be used in determining the 'normal' position of the gingival margin. The aim of this study was to do a systematic review of published clinical crown heights in the human permanent dentition to compare the measurements and to see if a clear trend with age exists. MATERIAL AND METHODS: An on-line literature search was done using the key words clinical crown height (or) clinical crown length. From January 1975 to August 2000, 11 published papers have listed measurements; three of these report on all tooth types, the remainder on anterior teeth. RESULTS: All studies used the same measuring technique but age group reporting differed as did the tooth types measured. Measurements from the 10 acceptable studies of the clinical crown height of the same teeth are comparable at similar ages, so published values are reasonable estimates of 'normality' for diagnosis. There is a statistically significant increase in clinical crown height of central and lateral incisors with age that slows as age increases.