Autogenous bone ring augmentation around single tooth implantation in the esthetic zone: A retrospective case series study with 2-3 years of follow-up

Abstract

Background: /purpose: Bone ring technique (BRT) is an effective method to reconstruct alveolar bone defects with simultaneous implant placement. This study aimed to evaluate the efficacy of the BRT in single maxillary anterior tooth implantation and its esthetic outcomes over 2-3 years of follow-up.

Materials and methods: Fifteen patients with single maxillary incisor loss received autogenous BRT with simultaneous implant placement. The vertical/horizontal bone gain, remaining vertical bone height (RVBH), remaining buccal bone width (RBBW), and vertical/horizontal bone resorption around implant over 2-3 years of follow-up were measured by using cone-beam computed tomography. Esthetic results including white esthetic score (WES), pink esthetic score (PES), and papilla index (PI) were evaluated by clinical recorded photographs.

Results: All implants showed evidence of osseointegration, and the mean vertical and horizontal bone gain of 14 sites was 5.55 ± 0.87 mm and 4.73 ± 0.70 mm, respectively. During 2-3 years of follow-up, all mean values of RBBW were more than 2 mm. Main vertical bone loss appeared within 4 months after surgery and the RVBH value decreased as the follow-up duration continued. Maximum buccal bone thickness resorption mostly appeared in the middle level of the implant during the primary two follow-up periods (P < 0.05). Esthetic results showed that the mean WES/PES was higher than 17, and more than half cases demonstrated relatively high PI (3 points) throughout the follow-up.

Conclusion: BRT could achieve excellent bone augmentation effect and can offer predictable esthetic outcomes for single tooth implant restoration in the esthetic zone.

Keywords: Alveolar ridge augmentation; Autograft; Bone ring technique; Esthetic zone; Maxillary incisor.

Figure 1

BRT surgical procedure in different conditions. A. Single maxillary right incisor lost with soft tissue collapse. B. Midcrestal incision with two vertical releasing incisions. C. Circular two-to three-wall defects. D. Recipient site measured and prepared with a solid bone grinding drill. E&F. Recipient and donor site after preparation. G. Bone ring fixed by the implant. H. Implant in the appropriate position. I. GBR. J. Soft tissue closure. K. Ring bone harvested from the chin region. L. Ring bone harvested in situ. M. A concentric type of central bone ring preparation. N. An eccentric type of central bone ring preparation. O&P. A healing cap with a large diameter and low height was used to fix the bone ring. BRT, bone ring technique; GBR, guided bone regeneration.

Figure 2

Measurement of the bone around the implant. A&B. CBCT data pre-surgery and 4 months post-surgery overlapped using Mevislab software. C. Vertical bone height and buccolingual horizontal bone width as measured by CBCT. D. Adjustment snapshot of XYZ screen in One Volume Viewer software. E. Measurement of mesial (MVBH) and distal (DVBH) bone height. F. Measurement of buccal (BVBH) and lingual (LVBH) bone height. G. Measurement of implant buccal bone thickness on a different plane. Platform = implant platform, 1/4 = 3 mm apically from the platform of implant, 1/2 = 6 mm apically from the implant platform, 3/4 = 9 mm apically from the implant platform, Apex = apex of the implant. BVBH, buccal vertical bone height; CBCT, cone-beam computed tomography; DVBH, distal vertical bone height; ILA, implant's long axis; LVBH, lingual vertical bone height; MVBH, mesial vertical bone height.

Figure 3

Dealing with bone ring exposure. A. Bone ring exposure on the lingual side 4 months post-surgery. The bone ring survived and was stable. B. 0.05% chlorhexidine was used to rinse the exposed part, and we removed the exposed bone and cornified mucosa with a tungsten steel drill. C. Completing the entire treatment. D. Exposed part was reduced 2 weeks post-treatment. E. Removing the exposed bone and the cornified mucosa with a tungsten steel drill. F. Second phase surgery was performed, with suturing of the exposed part. G. The exposed part had healed well 1 week later. H&I, The final ceramic crown.

Figure 4

BRT treatment procedure and vertical/horizontal bone gain in each patient included in the analysis. A. Representative photos from these patients' surgeries and radiographs during different follow-up periods. B. Vertical bone gain values after 4 months post-surgery as measured by CBCT. C. Horizontal bone gain values 4 months post-surgery. BRT, bone ring technique; CBCT, cone-beam computed tomography.

Figure 5

Vertical and horizontal bone resorption within different follow-up periods. A. Decreases in vertical bone height within different follow-up periods. B. Decreases in buccolingual bone width at the implant platform within different follow-up periods. C. Decreases in buccal bone thickness at a different plane of the implant within different follow-up periods.

Figure 6

A. Clinical photos of 6 BRT patients during 3-year follow-up. B. Frequency of PES assessment at baseline and follow-up of 5 variables (PES 1 = mesial papilla; PES 2 = distal papilla; PES 3 = curvature of the facial mucosa; PES 4 = level of the facial mucosa; PES 5 = root convexity/soft tissue color and texture); each was further rated with scores of 0–2 (2 = complete presence; 1 = incomplete presence; 0 = absence). C. Frequency of PI assessment at baseline and follow-up. PI ratings for the mesial and distal papilla (0 = no papilla present; 1 = less than half of the papilla height present [convex nature of the adjacent tissue]; 2 = more than half of the papilla height present, but not to the full extent of the contact point [papilla not in complete harmony]; 3 = papilla fills the entire proximal space and is in good harmony; 4 = papilla is hyperplastic). BRT, bone ring technique; PES, pink esthetic score; PI, papilla index.