THE MUCOSAL BARRIER FOLLOWING ABUTMENT DIS RECONNECTION - AN EXPERIMENTAL-STUDY IN DOGS/

In the present experiment, the effect on the marginal peri-implant tis sues following repeated abutment removal and subsequent reconnection w as studied. 5 beagle dogs were used. The mandibular premolars were ext racted and 2 fixtures of the Branemark System(R) were installed, 1 in each mandibular quadrant. 3 months later, abutment connection uas perf ormed. A 6-month period of plaque control was initiated. Once a month during the plaque control period, the abutment of the right side (test ) in each dog was disconnected, cleaned and reconnected to the fixture . Thus, each test abutment was removed and reconnected altogether 5x d uring this period. The contralateral abut-ment remained undisturbed fo r 6 months and served as control. 1 month after the last reconnection, the animals were sacrificed and tissue samples, comprising the implan t and the surrounding soft and hard peri-implant tissues, were obtaine d, decalcified, embedded in Epon and sectioned. The following landmark s were identified and used for linear measurements: PM (the marginal p ortion of the peri-implant mucosa). aJE (the level of the apical termi nation of the junctional epithelium), B (the marginal level of bane to implant contact), A/F (the abutment/fixture border). The findings ind icate that the dis- and subsequent reconnections of the abutment compo nent of the implant compromised the mucosal barrier and resulted in a more ''apically'' positioned zone of connective tissue. The additional marginal bone resorption observed at the test sites following abutmen t manipulation may be the result of tissue reactions initiated to esta blish a proper ''biological width'' of the mucosal-implant barrier.