An Investigation into the Relationship between the Thickness of Labial Bone in Anterior Maxillary Implants and the Labial Soft-Tissue Thickness

Statement of the problem: Soft-tissue problems (i.e., gingival recessions) are common in implantology, often associated with thin soft-tissue biotypes or buccally placed implants, and traditionally have been dealt with using the connective tissue grafts (1,2). The objective of this study was to explore the relationship between the thickness of labial bone in anterior maxillary implantsand the Labial Soft-Tissue Thickness (LSTT).

Materials and methods:32 patients (22 female and 10 male) participated in this retrospective study and had two implants placed in their maxillary arch, between the canines at either maxillary lateral incisor (#7 & 10), or central incisor (# 8 & 9) regions. Overall, 64 implants (20 Astra, 18 Strauman, 12 BHZ, 6 Zimmer, 6 Biomet, and 2 Lifecore implants) were placed. Implant diameters ranged from 3.3 to 4.6 mm. The implant position was determined using the cone beam CT scan (Picasso Duo, VATech) and by measuring the total ridge width and comparing the diameter of the implant and the surrounding bone thickness (labial bone, palatal bone). All patients had diagnostic (pre) and post-op cone beam CT scans. Using the cone beam CT scans, the labial bone thickness at the crest and mid-implant level were measured and recorded. The LSTT was measured using a Mitutoyo digital caliper at the crest level. The measurements of LSTT were performed approximately 4 months after placement of implants.

Methods of data analysis:Data for the LSTT were gender compared (independent t- test) . The Spearman’s correlation coefficients (rho) were used to assess the relationship between the implant’s labial bone thickness (at the crest and mid-implant level) and the LSTT.

Results:The independent t-test revealed no significant gender difference for the LSTT (2.46±0.88 and 2.43±0.90 mm for female and male patients, respectively). There were statistically significant relationships between the LSTT and the labial bone thickness at the crest (rho=0.720, p=0.000) and at the mid-implant level (rho=0.707, p=0.000).

Conclusion:Our findings suggest the labial soft-tissue thickness around implants is significantly related to the implant position and labial bone thickness. This questions the prevalent notion of using soft-tissue grafts to thicken the labial soft-tissue. There are indications that the soft-tissue graft may not be necessary most of the time, if the implant position is correct.

References:

1-Esposito M, Maghaireh H, Grusovin MG, Ziounas I, Worthington HV. Interventions for replacing missing teeth: management of soft tissues for dental implants. Cochrane Database Syst Rev. 2012 Feb 15;2:CD006697.

2-Chen ST, Darby IB, Reynolds EC. A prospective clinical study of non-submerged immediate implants: clinical outcomes and esthetic results. Clin Oral Implants Res. 2007;18:552-62.