Alveolar Ridge Alteration Following Immediate Implant Placement in Different Buccal Gap Distance
Alveolar Ridge Alteration Following Immediate Implant Placement in Different Buccal Gap Distance
Alveolar ridge resorption is an inevitable remodeling process following dental extraction. The buccal plate is especially predisposed to these phenomena. This may result in an increased risk of gingival recession and other adverse clinical effects that may decrease the predictability of implant placement or impair the final aesthetic result.1-2) The purpose of this study was to evaluate the optimal implant position for the preservation of the alveolar ridge in immediate implant placement and to compare this process with sites in which a xenograft was or was not inserted.
The mandibular third, and fourth premolars (3P3, 4P4) of six male hybrid dogs were bilaterally extracted with minimal flap surgery. The extraction sites were randomly divided into 6 groups: implant-buccal plate (I-BP) distance at 1 mm, 2 mm and 3 mm (with and without xenograft), with 8 sites per dog: mesial and distal roots of 3P3 and 4P4 sockets. The marginal gap was filled with xenograft on the right side and it was left empty in the left side as a control group. Two and four months later, biopsies of the implant sites were taken for measurements and Micro-computed tomography analysis.
Three-way interaction analysis of variance was employed to determine if any significant differences (Bonferroni post-hoc test, p <0.05) present across the three independent variables (I-BP distance, xenograft effect and time period) in bone volume (BV) and bone mineral density (BMD). The buccal tissue thickness (BTT) was analyzed among groups with non-parametric analysis (Kruskal-Wallis test, p <0.05).
Marked hard tissue alteration occurred after immediate implant installation. The marginal gap between the implant and the walls of the socket was filled and showed the difference among the three experimental groups (Table 1) especially on the buccal site. The change of buccal tissue thickness, bone volume and bone mineral density were compromised in jaws in I-BP distance of 1 mm group compared to those in 2 mm and 3 mm groups. The BTT, BV and BMD were significantly highest in 3 mm group compared to those in 1 mm and 2 mm groups. There was no extensive difference among these 3 groups in the xenograft and control groups. Lingual bone remodeling also did not reveal any significant differences among the groups (p <0.05).
Tables: The bone volume (mm3), bone mineral density (mg/cm3) and buccal tissue thickness (mm) of the control and the xenograft groups at 2 months and 4 months post-implantation. The data are presented in mean ± SD.
BV (mm3)
| 1mm
| 2mm
| 3mm
|
CTRL 2mth
| 254±25.8
| 289±21
| 322±25.5
|
CTRL 4mth
| 151±13.4
| 252±28
| 264±43
|
Graft 2mth
| 256±18.3
| 305±25.8
| 316±19.3
|
Graft 4mth
| 156±16.3
| 19.1±26.3
| 267±19.9
|
BMD (mg/cm3)
| 1mm
| 2mm
| 3mm
|
CTRL 2mth
| 757.62±34.8
| 802.62±28.4
| 818.78±28.7
|
CTRL 4mth
| 693.45±74.1
| 781.87±33.5
| 836.23±40.4
|
Graft 2mth
| 776.75±16.5
| 817.62±30.8
| 818.08±28.6
|
Graft 4mth
| 732.05±8.7
| 758.63±6.2
| 834.37±13.4
|
BTT (mm)
| 1mm
| 2mm
| 3mm
|
CTRL 2mth
| 1.23±0.5
| 0.84±0.3
| 1.33±0.6
|
CTRL 4mth
| 0.59±0.16
| 0.84±0.3
| 1.77±0.2
|
Graft 2mth
| 0.65±0.4
| 1.13±0.6
| 1.68±0.4
|
Graft 4mth
| 0.3±0.1
| 0.8±0.2
| 1.47±0.2
|
These finding suggest that I-BP distance drastically influences the change of the BTT, BV and BMD of an implant surrounding bone. The 3 mm I-BP distance is the optimal implant position in preventing buccal bone resorption, promoting new bone formation and resulting in esthetic implant outcome.
References:
1) W. Rogers and E. Applebaum, "Changes in the mandible following closure of the bite with particular reference to edentulous patients," Journal of the American Dental Association, vol. 28, p. 1573, 1941.
2) J. Pietrokovski and M.Massler, "Ridge remodeling after tooth extraction in rats," Journal of Dental Research, vol. 46, no. 1, pp. 222–231, 1967.