LA ENSEÑANZA-APRENDIZAJE EN EL USO DE LOS MUSEOS COMO RECURSO EDUCATIVO

The baseline clinical measurements of the GTR test sites were found to be not significantly different from those of the CF sites, using the Mann- Whitney U test (p > 0.05). Similarly, there was no statistically significant differences when the measurements at 6 months were compared between these two groups (p > 0.05). However, when the changes in these measurements were compared, the reduction in PPD of the GTR sites was greater than the CF sites and this difference was statistically significant (p < 0.05). Although gain in CAL was also greater in the GTR sites, the

difference was not significant (p = 0.08). Similarly, change in REC in the GTR sites was not significantly different from that in the CF sites (p > 0.05). Thus, although the baseline characteristics of periodontal defects were similar, the PPD reduction in defects treated with GTR surgery was statistically significantly different from that in defects treated with CF surgery.

6.4 DISCUSSION

The clinical outcome of GTR therapy was evaluated in this part of the study. The treatment using GTR resulted in a significant PPD reduction of 4 mm at 6 months. Similar findings have been reported (Sander at a/. 1994), although smaller (Kersten at a/. 1992; Proestakis at a/. 1992; Bragger at at. 1992; Teparat at a/. 1998) or larger reductions in PPD also have been shown (Cortellini at at. 1993a; Becker and Becker 1993; Cortellini at a/. 1995; Cortellini at at. 1996a; Kiliç at a/. 1997). A significant gain in CAL of 4 mm was achieved in the present study. Similar gains in CAL were reported also by Cortellini at a/. (1993a; 1995), Becker and Becker (1993) and Kiliç at a/. (1997) for human intrabony defects treated by non-resorbable membranes. However, CAL gain in the present study was higher than the results of several studies where vertical bone defects were treated by GTR (Bragger at a i 1992; Kersten at a i 1992; Proestakis at a i 1992; Sander at a i 1994; Nowzari at a i 1995; Teparat at a i 1998). Gottlow at a i (1992) defined the sites which had gained 2 mm or more CAL after 6 months of GTR surgery as ‘successfully treated'. Based on this definition, the clinical outcome of nearly all periodontal defects (94%) treated by GTR in the present study was considered as successful.

Since the early case report of Gottlow at a i (1986) clinical trials using GTR have shown considerable variation in outcome. The amount of residual periodontal support, defect depth and configuration, membrane exposure and contamination, coverage of the newly-formed tissue by the gingival flap, compliance with a supportive periodontal maintenance program and smoking habit have all been suggested as factors which may effect the results of GTR therapy (Selvig at a i 1992; Selvig at a i 1993;

Tonetti et al. 1993; Sander et al. 1994; Nowzari et al. 1995; Cortellini et al. 1995; Tonetti et al. 1996; Machtei et al. 1996; Cortellini et al. 1996a; Nowzari et al. 1996; Garrett 1996). One or more of these factors may thus have been the cause of differences between the present study and previously published studies.

The surgical procedures in previous GTR trials have been performed by experienced investigators, which has an impact on the clinical outcome of GTR therapy (Cortellini et al. 1993a; Cortellini et al. 1996a). However, the present study was not planned as a well controlled clinical trial and therefore, it represents more realistic conditions in a routine clinic where the operations are performed by a number of dental surgeons who posses different levels of experience, knowledge and practical skill. Nevertheless, the results of this study indicated that GTR therapy resulted in significant clinical improvements, including reduction in PPD and gain in CAL.

The periodontal defects treated with CF surgery in the present study resulted in a PPD reduction of 3.5 mm and a gain in CAL of 3 mm. These results were consistent with those obtained by Cortellini et al. (1995; 1996a) and indicated that this treatment also results in significant clinical improvements, as reported by Lindhe et al. (1982). CF surgery displayed significantly less PPD reduction than the GTR therapy, in agreement with the study of Cortellini et al. (1995) and Kiliç et al. (1997). However, despite larger gains in CAL for the GTR compared to the CF group, there was no significant difference between these two treatment modalities in CAL gain, in contrast to the studies of Cortellini et al. (1995; 1996a).

Recession of marginal gingiva after GTR surgery is an expected side effect (Gottlow et al. 1986; Cortellini et al. 1993a). However, in the present study there was very limited recession of the marginal gingiva not only in the GTR test sites, but also in the adjacent GTR control sites and the defects treated by conventional surgery. Therefore, it can be assumed that the REC measured in the GTR group was a normal outcome of the periodontal surgical procedure and may not be directly related to the membrane placement.

The finding that the RT exceeded the crestal alveolar bone level indicated that this therapy promoted total defect fill by soft regenerated tissue, which was red and jelly-like in appearance but firm and resistant to probing forces. The amount of the RT observed in the present study was within the range of previously published reports which showed a mean RT ranging from 4 to 8 mm (Tonetti at s i 1993; Tonetti at al. 1996).

In addition to the periodontal defect sites treated using ePTFE membranes, the clinical measurements of healthy sites adjacent to these defect sites were also monitored in this study. While a 0.5 mm reduction in PPD was observed, GTR surgery did not result in any change in CAL. This finding is consistent with the study by Stein at al. (1993) who reported a mean CAL loss of 1 mm which was not significantly different from the healthy sites that were covered by a non-resorbable membrane.

6.5 CONCLUSIONS

Based on the findings of this part, it was concluded that

i) the periodontal defects treated with GTR show significant clinical improvements, including significant reduction in PPD and clinical attachment gain, at 6 months after surgery and therefore they may represent the periodontal sites which heal by regeneration.

ii) The finding that the periodontal defects treated with CF also exhibit clinical improvements suggest that these sites may heal by both repair and regeneration processes.

iii) The GTR control sites also show some changes in clinical measurement after GTR surgery.

In summary, the periodontal defects treated by GTR healed by regeneration, and therefore the GCF samples collected from these sites represent the fluid of a regenerating periodontal wound and are consequently used to investigate certain molecules described in the next part below.

PART II: GROWTH FACTORS AND THEIR RECEPTORS