Original study - ZZI 02/2011

Evaluation of the influence of preoperative factors
on soft tissue consolidation around single tooth implants
in the esthetic zone – A pilot study

The mean implant PES was 6.55 ± 3.76 at the first evaluation and 6.55 ± 3.74 at the second evaluation.

 

Univariate analysis

The patient-related factors of age and gender had no significant influence on the “red esthetics”. Implants placed in patients with tooth loss as a result of carious/periodontal lesions achieved a PES of 5.8 ( 3.4), implants inserted because of aplasia achieved a PES of 7.6 ( 2.6) and implants following dental trauma achieved a PES of 4.2 ( 3.7). Statistically significant differences between the groups were found using the Kruskal-Wallis test (p = 0.029). As a result of the small size of the group, however, no further multivariate analysis took place.

Implants in the maxilla had a PES of 6.0 ( 3.6) while mandibular implants demonstrated a PES of 5.8 ( 3.1). The difference was not statistically significant. Implants in single tooth gaps had a PES of 6.8 (+ 3.8) while the PES obtained for implants in saddle gaps where more than one tooth was missing was 5.2 (+ 3.1). A highly significant difference (p < 0.01) was found using a U-test (Fig. 3). Implants inserted in local bone demonstrated a PES of 7.8 (+ 3.1); a PES of 4.9 (+ 3.0) was recorded after minor augmentation measures using intraoral bone, and a PES of 2.6 (+ 1.8) was found after bone augmentation with free avascular grafts from the iliac crest. A statistically highly significant difference (p = 0.02) was found between the groups. A PES of 8.5 (+ 3.3) was achieved with transgingival healing, and crestal incision opening (stretching) resulted in a PES of 4.7 (+ 1.9). The PES was 4.8 (+ 2.7) after oro-vestibular transposition, a PES of 6.4 (+ 3.5) was obtained with exposure by means of a palatal roll, use of papilla regeneration achieved a PES of 7.8 (+ 2.1) and partial vestibuloplasty/apically positioned flap with free mucosal graft resulted in a PES of 2.6 (+ 2.2). A statistically highly significant difference (p < 0.01) was found between the groups. Furthermore, the SAC classification demonstrated a statistically significant (p < 0.01) influence on the PES.

None of the treatment-related factors had a significant influence on the PES.

Multivariate analysis

In summary, the relationships between the individual para-meters in the complex interplay were found by linear regression. It was established that the group (single tooth implant/neighboring implants), the SAC classification and the need for augmentation with extraoral bone were valid variables for describing the PES and thus the esthetic outcome.

 

H0: mean PES = b0 + b1 x aug. ex. +b2 x SAC1 +b3 x SAC2 +b3 x group = 0.5 (Table 1)

 

The corrected coefficient of determination (R-squared) for this final model was 0.632. Whether the implant was placed directly in local bone or whether small local defects were augmented with intraoral bone had no significant influence on the PES (p = 0.47). The cause of the tooth loss and also the incision chosen for uncovering the implant were not necessary for description of the PES.

Discussion

Our results show that there are highly significant statistical differences in the PES of single tooth implants compared with restorations of neighboring implants. An explanation for this might be the bone resorption described by Tarnow between neighboring implants and the resulting deficiency of hard and soft tissue [27, 28]. Resorption of the interimplant bone leads to shortening of the papilla and ultimately to impairment of red and white esthetics.

The preoperative defect size, due, for instance, to atrophy and trauma, had a crucial influence on the final esthetic result of implant-borne rehabilitation. Extensive hard and soft tissue defects required extensive reconstructive measures prior to implantation. The esthetic outcomes depending on the SAC classification are analogous. It was shown that cases classified as “simple” and “advanced” SAC treatment concepts led to more attractive outcomes, while some “complex” cases achieved a lower PES, indicating an esthetically unsatisfactory outcome.

The influence of different surgical protocols [8, 10, 13, 23, 24] and prosthetic loading concepts [4, 6, 8, 12, 13] on estheti-cally successful implant restorations is also discussed. However, objective esthetic parameters have hardly been considered hitherto, so that comparison of the results was not possible [12, 21]. Using the Pink Esthetic Score, our study showed that neither the surgical time management nor the prosthetic loading concept have a statistically significant influence on the final esthetic outcome. This is in line with the studies of Jokstad and Carr, who also found no esthetically significant difference between immediately and conventionally loaded implants [14].

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