Treatment outcomes of ligature-induced recession in the dog model using guided tissue regeneration or coronally positioned flap procedures.

AIM

The aims of the study were: (1) to determine the quality of the hard and soft tissues formed in segments treated with coronally positioned flaps alone (CPF group) or combined with a polylactic acid resorbable membrane (guided tissue regeneration--GTR group) in wide type defects (canine teeth), and (2) to evaluate the behaviour of the newly regenerated tissues to an experimentally induced inflammation initiated by microbial plaque at the submarginal level in recession type defects (premolar teeth).

MATERIALS AND METHODS

The randomized block design was used in the study, with each dog receiving both treatments (GTR and CPF). Gingival recession defects were surgically created in the 2nd and 4th mandibular premolars and, after 10 weeks, also in the maxillary canines of three dogs. The defects in the premolar area were created earlier than the defects in the canine teeth so that both areas would be ready for biopsy at the same time. Two months after the creation of the defects the exposed roots in the control group of teeth were surgically covered with coronally positioned flaps only (CPF group), and in the test group of teeth a coronally positioned flap was used in combination with a resorbable membrane (GTR group). In the premolar teeth only, after a healing period of five months, cotton ligatures were placed intrasulcularly and these areas were left without plaque control for 10 weeks. Following this, biopsies were taken from the canines and the premolars in order to examine (1) the quality of the hard and soft tissues formed after five months of healing in the canine teeth and (2) the response of the newly formed tissues to microbial accumulation induced by the subgingival ligature placement.

RESULTS

In the wide defects of the canine teeth, the use of the membrane produced a mean new attachment formation of 44%, while the repositioned flap technique produced 22% new attachment. The regeneration of bone was limited to the apical area for both techniques and amounted to 15% and 10%, respectively. In the narrow defects of the premolars both techniques produced comparable mean root coverage percentages. The inflammatory conditions created in the study led to a comparable loss of mean clinical attachment and an increase in tissue recession and the extent of the inflammatory process for both groups.

CONCLUSIONS

The use of resorbable membranes for the treatment of wide recession type defects in the canine teeth (GTR group) produced significantly better clinical results, with higher mean root coverage and increased regenerative capacity of the periodontal tissues, compared with the coronally positioned flap technique (CPF group). Additionally, the regenerated tissues created after the use of both techniques in narrow recession defects (premolar teeth) demonstrated comparable resistance to the microbial accumulation conditions created.