Performance of 400 adhesive bridges fitted in a restorative dentistry department

The purpose was to present a descriptive report of the clinical performance of adhesive bridges fitted in a university department of restorative dentistry. The case records of 400 consecutive adhesive bridges fitted between November 1984 and June 1989 in the School of Clinical Dentistry, Queen's University, Belfast were reviewed. The majority of the bridges (66 per cent) were of a fixed-fixed Maryland design; the remainder were Maryland cantilevers (18 per cent), hybrids, i.e. Maryland cantilevers which slotted into conventional units (8 per cent), and Rochette bridges (6 per cent). The mean duration of clinical service at review was 2.7 years. One hundred (25 per cent) of the bridges debonded on at least one occasion. Of the bridges which debonded the average number of debonds was 1.7, with the first debond happening on average 10.7 months after placement (range 1-42 months). Fifty-seven (14 per cent) debonded on one occasion only; 25 (6 per cent) debonded twice and 18 (5 per cent) debonded on three or four occasions. The length of clinical service was a significant factor in relation to debonding. A lower proportion of posterior than anterior bridges debonded and cantilevered and hybrid designs performed well. It is concluded that this investigation confirms the efficacy of resin-bonded bridgework used to replace both anterior and posterior teeth.

The effects of subgingival irrigation with low dosage metronidazole on periodontal inflammation

The effects on chronic periodontitis of a simplified oral hygiene regimen combined with subgingival irrigation with 0.5% metronidazole were investigated. 19 patients, with 548 pockets greater than or equal to 4 mm, completed a 3-month randomised double-blind placebo-controlled trial. At day 0, prior to treatment, and at days 7, 28, 56 and 84, plaque index, sulcus bleeding index and probable pocket depth were recorded. The simplified oral hygiene regimen consisted of (1) one episode of root debridement, removal of subgingival approximal overhangs on restorations and subcontact area debridement with abrasive strips and polishing, and (2) instruction in Bass brushing (twice daily) with no stress on interdental cleaning. After baseline debridement, patients were allocated 0.5% metronidazole or a placebo. They were instructed to irrigate subgingivally once daily for 28 days. Treatment resulted in marked improvement in both groups and proportionately more sites improved in the metronidazole group at 28, 56 and 84 days. There were no significant differences between the procedures at any time. It was concluded that a simplified oral hygiene regimen combined with daily subgingival irrigation with 0.5% metronidazole or a placebo was effective in reducing periodontitis for at least a further 8 weeks, and that proportionately more sites improved in the metronidazole group.

The effects of a simplified mechanical oral hygiene regime plus supragingival irrigation with chlorhexidine or metronidazole on subgingival plaque

23 patients with pockets greater than or equal to 4 mm and evidence of bone loss on radiographs received thorough scaling and root planing followed by instruction in Bass brushing. They refrained from routine interdental cleaning for the first 28 days. A pulsating jet irrigator was used once daily supragingivally with 0.02% chlorhexidine (CH) 0.05% metronidazole (MD) or 0.01% quinine sulphate inactive control (PL), on a randomized double blind basis. Molar sites were not irrigated and served as control sites; they were only mechanically cleaned. For each patient, subgingival plaque samples were obtained from 2 test and 1 control sites at baseline (day 0), and on days 7, 28, 56 and 84. Plaque samples were monitored by darkfield microscopy on the basis of morphological characteristics of 4 types of bacteria: cocci, motile cells, spirochaetes and "others" (nonmotile rods, filaments and fusiforms). The simplified oral hygiene regime of scaling, root planing and Bass toothbrushing combined with interdental supragingival pulsating jet irrigation with CH, MD or PL appeared superior to a system of simplified oral hygiene alone, particularly during the first 4 weeks. However, at most time-points, the benefits were not statistically significant except for metronidazole. By day 84, the end of the experimental period, all groups approximated baseline levels. The results indicate that supragingival pulsated jet irrigation has limited effects on the composition of subgingival plaque. More marked changes occur when the irrigation fluid contains a chemical agent such as metronidazole known to be effective against important subgingival organisms, but probably not to such an extent as to change the composition of the flora from one associated with diseased sites to one associated with healthy sites.

Bone induction in implants of decalcified bone and dentine

The fate of decalcified bone and dentine implanted in muscle and beneath the kidney capsule has been studied in young rats. Quantitatively speaking there was a great deal of variation, but in general the implants became surrounded and invaded by young vascular connective tissue; then tunnels were eroded and cavities enlarged by multi-nucleated giant cells; then the matrix around erosion chambers became recalcified; and finally new bone was induced on the eroded recalcified surfaces. Erosion was much more extensive, and bone was much more readily induced in the intramuscular than in the subcapsular implants. It is concluded that the presence of an eroded, recalcified surface is a pre-requisite for bone induction under these conditions.