The ovate pontic design: a histologic observation in humans.
BACKGROUND
Fixed partial dentures with an ovate pontic design contacting the underlying soft tissue may interfere with long-term mucosal health.


OBJECTIVE
The purpose of this study was to examine the clinical and histologic characteristics of the human alveolar ridge mucosa adjacent to an ovate pontic-designed restoration.


METHODS
Twelve patients requiring maxillary fixed partial dentures (either implant- or tooth-supported) with a pontic site in the premolar or molar region were studied. The pontics had an ovate design and were adapted to the underlying mucosa with tight but noncompressive contact. Patients used Super Floss once a day to clean the infrapontic area. After 12 months, soft tissue biopsy specimens about 3 x 3 mm in size were obtained (1) from the ridge mucosa in contact with the pontic (test site) and (2) from an adjacent uncovered masticatory mucosal area (control site). Histometrically, the thickness of the epithelium and the keratin layer and the height of the connective tissue papillae were measured. Morphometrically, the composition of the connective tissue of the specimens was analyzed in a 200-microm-wide zone immediately subjacent to the epithelium (zone A) and in a 200-microm-wide central connective tissue portion (zone B). A point-counting procedure was used to calculate the relative proportions occupied by collagen, fibroblasts, vascular structures, inflammatory cells, and residual tissue. Differences between the tissue fractions in test and control sites were analyzed with the Wilcoxon signed rank test (.05 level of significance).


RESULTS
At 12 months, only 3 pontic sites showed clinical signs of mild inflammation, whereas the other test sites and all control sites appeared healthy. A thinner keratin layer was observed in pontic sites than in control sites (8 microm vs 22 microm). Larger tissue fractions of inflammatory cells were found in pontic sites than in control areas in the zone immediately subjacent to the epithelium.


CONCLUSIONS
Within the limitations of this study, restoring an edentulous space with an ovate pontic supported by adequate oral hygiene measures was not associated with overt clinical signs of inflammation. Histologically, however, this pontic design was associated with a thinner keratin layer and with changes in the composition of the connective tissue compartment subjacent to the epithelium.
Zitzmann
Nicola Ursula
NU
Dental School, University of Basel, Basel, Switzerland. N.Zitzmann@unibas.ch
Marinello
Carlo Paolo
CP
Berglundh
Tord
T
D000328:Adult; D000368:Aged; D003188:Composite Resins; D003238:Connective Tissue / Q000473:pathology; D003776:Dental Porcelain; D003779:Denture Design; D003830:Denture, Partial, Fixed / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007633:Keratins; D008297:Male; D008437:Maxilla; D008875:Middle Aged; D009061:Mouth Mucosa / Q000473:pathology; D009910:Oral Hygiene; D018709:Statistics, Nonparametric; D013282:Stomatitis, Denture / Q000209:etiology* / Q000473:pathology; D014093:Tooth, Artificial / Q000009:adverse effects*; D016896:Treatment Outcome
D003188:Composite Resins; D003776:Dental Porcelain; D007633:Keratins