The effect of thick mucosa on peri-implant tissues: an experimental study in dogs

Findings from animal studies have indicated that the implant-mucosal barrier consists of a junctional epithelium approximately 2 mm long and a connective tissue compartment about 1 to 1.5 mm high. It may be argued that different features develop in the implant-mucosal barrier when it is placed within the alveolar bone with thick mucosa. The aim of this study was to examine the influence of a thick mucosa on peri-implant tissue healing around dental implants.

The bilateral fourth mandibular premolars and all maxillary premolars were removed in six mongrel dogs. On one side (test side) of the mandible, a standardized bone defect (8.0 mm in height) was created in the premolar region, whereas no defect was created on the other side (control side). After 3 months of healing, one implant was placed on each side of the mandible; a long abutment (12 mm in height) was connected to the fixture on the bone defect side, whereas a normal abutment was connected to the fixture on the control side. After a healing period of 6 months, all dogs were sacrificed to evaluate peri-implant tissues.

The height of the mucosa, the length of the junctional epithelium, and the height of the zone of connective tissue integration were significantly greater in the thick mucosa than in the normal mucosa (P <0.05). No significant difference was found between the control and test sides in the marginal level of bone-to-implant contact.

The junctional epithelium extended more apically in the thick mucosa than in the normal mucosa. However, additional marginal bone resorption was not observed at the thick mucosa sites.