The effect of partial dentureconnectors on gingival health

Sandra Orr\ Gerard J. Linden^ andHubert N. Newman'^Department of Restorative Dentistry, Queen sUniversity ot Belfast, UK: ^insiitute of DentalSurgery, University of London, UK

Orr S. Linden GJ and Newman HN: The effect of partial demure connectors ongingival health. J Clin Periodontol 1992; 19: 589-594.

Abstract. The effect on the gingiva of a variety of relationships of a removablepartial denture connector to the gingival margin was investigated in 10 subjects.Acrylic resin baseplates were designed incorporating a variety of relationships ofthe connector to the gingival margin. The appliances were worn for a 12 hourperiod daily, for 21 days. At baseline and at days 7, 21 and 49. plaque index,gingival index and probing pocket depth measurements were recorded, andsubgingival plaque samples were examined using darkfield microscopy. No in-crease in plaque accumulation was detected in any area at any time interval.There was a significant increase in gingival index at day 21 in areas where theappliance covered the gingival margin. Small increases in probing pocket depthwere recorded at day 21. there being no difference between any of the test areas.Baseline values were re-established by day 49, No significant differences weredetected in the percentage of motile organisms or spirochaetes counted in thesubgingival plaque samples collected from any area. It was concluded that deterio-ration in gingiva] health occurred rapidly following the insertion of a removableappliance, and that coverage of the gingiva] margin, irrespective of the degree ofgingival relief, had a detrimental effect.

Key words: partfal dentures: plaque: gingivatinfiammation.

Accepted for publication 6 August 1991

El Ghamrawy (1976), Addy and Bates(1979) and Stipho et al. (1978) foundremovable partial dentures were associ-ated with increased plaque accumu-lation, not only on tooth surfaces indirect contact with the denture but alsoon teeth in the opposing arch, and insome cases, even on buccal surfaces ofteeth. Several studies have shown in-creased or continuous periodontalbreakdown in patients fitted with par-tial dentures (Carlsson et ai, 1965, Der-ry & Bertram 1970. Rissin et al. 1979),It is possible to reduce the effect of re-movable partial dentures on the peri-odontium. Bergman et al. (1982) andChandler & Brudvik (1984) demon-strated only minor periodontal effectsin patients recalled regularly for sup-portive treatment, including pro-fessional oral hygiene. Taken togetherthese studies suggest that the insertionof a partial denture constitutes a riskfactor for periodontal health. One par-ticular problem may be the relationshipof the denture connector to the gingivalmargin, Bissada et al. (1974) concludedthat if tooth approximation was necess-ary, the gingiva! margin should be re-lieved, i.e. there should be a spaceunderneath the denture base, whereasHobkirk and Strahan (1979) concluded

that the appliance should be very closelyapplied to the gingival margin.

The aim of this study was to investi-gate the effect on the gingiva of a varietyof relationships of a removable partialdenture connector to the gingival mar-gin. In addition darkfield microscopywas used to examine associated micro-biological changes, in an attempt toidentify whether a disease-associatedflora became established in the periodshortly following the insertion of a re-movable partial denture.

Material and Methods10 healthy adult volunteers were se-lected from Dental Surgery Assistantsworking at the Eastman Dental Hospi-tal. London. Each subject had an intactmaxillary arch, adequately restoreddentition and displayed no occlusal ab-normalities. The purpose and design ofthe study were explained clearly to eachsubject and voluntary informed consentobtained. None had previously worn aremovable appliance, nor had they anymedical condition which contra-indi-cated their inclusion in the study, Alisubjects were right-handed.

The upper first premolars and firstmolars were selected as test teeth, and in

each subject the upper second premolarswere present so that the test teeth werenot contiguous. Two mandibular teethwere chosen as controls. In each subjectthe mean gingival index was

590 Orr el al

Fig. I. Heat-cured acrylic resin baseplate, covering the palatal gingivae from the upper canineto the second molar, retained by embrasure hooks. The test areas incorporated into the designof the baseplate are labelled.

gival crevices on the mesio-palatal as-pect of the test and control teeth, usinga Gracey pattern curette number 5/6,The plaque samples were transferred tobijou bottles containing 0,2 ml of 0,85%saline, and the resulting plaque suspen-sions were dispersed by expulsion tentimes through a 25 gauge needle. Onedrop was applied to a microscope slidewhich was cover-slipped and sealed withnail varnish to reduce evaporation andstreaming, A darkground system (Stan-dard 14, Zeiss, Oberkochen, Germany)was used to examine the slides at a mag-nification of X 1000 under oi! immer-sion. All slides were prepared and exam-ined within one hour in an attempt toreduce loss of bacterial motility(Omar & Nevmian 1986), 200 bacteriafrom randomly selected fields werecounted and classified into the fourmorphological groups as described byMousques et al. (1980): coccoid cells.

motile organisms, spirochaetes andother morphotypes.

The subjects were instructed in theBass method of brushmg. which was tobe performed twice daily, and suppliedwith an Oral B 35 brush (Oral B Lab-oratories Ltd. Aylesbury, Bucks, Eng-land,) and Crest Toothpaste (Crest.Procter & Gamble, Newcastle, Eng-land), The appliances were then in-serted, adjusted to be in harmony withthe occlusion, and the subjects instruct-ed to wear them 12 hours daily, duringwaking hours, for a period of threeweeks. Clinical measurements andplaque samples were obtained after 7and 21 days, A fmal assessment wascarried out at day 49, four weeks afterdiscarding the appliance.

Statistical investigations

Changes which occurred within areaswere evaluated using Wilcoxon matched

Table I. Test areas incorporated into the design of the acrylic resin baseplate

Test area Tooth Relationship of frameworkthe appliance covered and was closely applied to the gingival margin

BASELtNE 7 DAYS

40 -

20 -

DO -1

SO -

60 -

40 -

20 -

21 DAYS

i

KJ TOO