Background: So far, the clinical effects of the placement of a resorbable m
embrane for guided tissue regeneration have not been studied in humans in g
reat detail. The dynamics of the resorptive processes, in particular, appea
r to be rather speculative. In the present longitudinal study, specific alt
erations of the dimensions of the dentogingival mucosa were explored after
surgical root coverage by using a bioresorbable membrane and a coronally-re
positioned flap.
Methods: The study population consisted of 14 patients with a total of 31 p
redominantly shallow, Miller class I, II or III recessions. The thickness o
f the masticatory and lining mucosa before and after surgical intervention
was measured with an ultrasonic device.
Results: Mean (+/-sd) recession depth and width were 2.85+/-1.29 and 4.46+/
-1.14 mm, respectively. After 12 months, 51+/-29% of the recession depth (p
< 0.001) and 13+/-35% of its width (n.s.) were covered. Root coverage seem
s to be rather defect-type sensitive with best results obtained at canines
with relatively shallow recessions. Mucosal thickness was considerably incr
eased after surgery with a gradual decrease during the following 9 months.
Thus, thickness of the marginal tissue rose from 0.82+/-0.27 mm to 1.49+/-0
.54 mm 3 months after placement of the membrane (p < 0.001). After 12 month
s, a mean thickness of 1.03+/-0.40 mm was observed (p < 0.001). Even more p
ronounced alterations were noted for the alveolar lining mucosa with a thre
efold increase of thickness 3 months after surgery and a gradual decrease t
o about 1 mm after 12 months.
Conclusions: The present results point to the considerable space making cap
acity of the bioresorbable membrane which probably allows for the ingrowth
of a granulation tissue derived from the underlying structures. The gradual
decline in mucosal thickness between months 6 and 9 after surgery may be p
aralleled by the maturation of the granulation tissue while complete resorp
tion of the membrane had been accomplished.