Research Abstracts - Implant Dentistry

AIM: To test whether or not the use of short dental implants (6 mm) results in an implant survival rate similar to long implants (11 mm to 15 mm) in combination with sinus grafting.
METHODS: This multicenter study enrolled 101 patients with a posterior maxillary bone height of 5 mm to 7 mm. Patients randomly received short implants (6 mm) (group short) or long implants (11 mm to 15 mm) with sinus grafting (group graft). Six months later, implants were loaded with single crowns and patients re-examined at 1 year of loading. Outcomes included treatment time, price calculations, safety, patient-reported outcome measures (OHIP-49 = Oral Health Impact Profile), and implant survival.
RESULTS: In 101 patients, 137 implants were placed. Mean surgical time was 52.6 min (group short) and 74.6 min (group graft). Mean severity scores between suture removal and baseline revealed a statistically significant decrease for most OHIP dimensions in group graft only. At 1 year, 97 patients with 132 implants were re-examined. The implant survival rate was 100%.
CONCLUSIONS: Both treatment modalities can be considered suitable for implant therapy in the atrophied posterior maxilla; short implants may be more favorable.

Implant placement in regions with limited vertical bone height presents limited implant treatment options for some patients. Improved implant surface technology and design support the use of short dental implants in these situations. This study demonstrates that the success rate of short implants and longer implants are comparable. Importantly, patient satisfaction with short-implant therapy is higher than for alternative therapies involving regenerative surgical procedures to accommodate longer implants. The multiple advantages of short implants should be considered as one alternative in treatment of the atrophied posterior maxilla.

Cooper LF, Reside G, Raes F, et al. Int J Periodontics Restorative Dent. 2014;34(4):477-486.

OBJECTIVE: This clinical study assessed at 5 years both implant survival and peri-implant tissue architecture of immediately provisionalized implants placed 4 to 6 months following augmentation with demineralized bovine bone allograft and collagen membrane.
RESULTS: Of 23 implants placed in 19 patients, one implant failed prior to loading (95.6% survival). Implant tissue relationships were stable following implant placement; marginal bone level changes from implant placement to 5 years (mean ± SD: -0.18 ± 0.79 mm, range: -1.6 to 1.4 mm, P = 0.51), the mesial and distal papilla length changes (mesial mean ± SD: 1.14 ± 0.92 mm, P < 0.001; distal mean ± SD: 0.74 ± 1.46 mm, P = 0.04), and the unchanged mucosal zenith location (mean ± SD: 0.24 ± 0.93 mm, P = 0.15) were recorded. There were no major surgical complications during the 5-year period.
CONCLUSIONS: When augmentation is required, subsequent dental implant placement in the anterior maxilla may be achieved using immediate placement and provisionalization protocol to attain osseointegration success and stable peri-implant tissue responses.

In addition to functionality, a critical factor in successful dental implant therapy is providing patients with optimal esthetics. Indeed, this is key to patient satisfaction and plays a vital role in improving quality of life. In this and other studies, hard- and soft-tissue stability was observed from the time of crown placement and up to 5 years, and this was reported for implants placed in healed sites, for immediately installed implants in extraction sockets, and for implants placed in augmented sites. Immediate provisionalization offers several benefits for patients and is one clinical pathway to implant esthetic success. The positive 5-year outcomes seen in this study are indeed promising; however, it should be noted that the general lack of long-term data requires that patients be carefully monitored and managed over the lifetime of implant function.

Sousa V, Mardas N, Farias B, et al. Clin Oral Implants Res. 2015 Sep 18. doi: 10.1111/clr.12684. [Epub ahead of print]

OBJECTIVES: The purpose of this study was to investigate the effect of treated periodontitis on implant outcomes in partially edentulous individuals compared with periodontally healthy patients.
MATERIAL AND METHODS: Longitudinal studies reporting on implant survival, success, incidence of peri-implantitis, bone loss, and periodontal status, and on partially dentate patients with a history of treated periodontitis were included.
RESULTS: The search yielded a total of 14,917 citations. Twenty-seven publications met the inclusion criteria for qualitative data synthesis. Implant success and survival were higher in periodontally healthy patients, while bone loss and incidence of peri-implantitis was increased in patients with history of treated periodontitis. There was a higher tendency for implant loss and biological complications in patients previously presenting with severe forms of periodontitis. The strength of the evidence was limited by the heterogeneity of the included studies in terms of study design, population, therapy, unit of analysis, inconsistent definition of baselines and outcomes, as well as by the inadequate reporting of statistical analysis and accounting for confounding factors; as a result, meta-analysis could not be performed.
CONCLUSIONS: Implants placed in patients treated for periodontal disease are associated with higher incidence of biological complications and lower success and survival rates than those placed in periodontally healthy patients. Severe forms of periodontal disease are associated with higher rates of implant loss. However, it is critical to develop well-designed, long-term prospective studies to provide further substantive evidence on the association of these outcomes.

Tooth loss associated with advanced, localized, and generalized periodontitis represents common reasons for dental implant-based tooth replacement. The present systematic reviews show that periodontitis-susceptible patients have a higher incidence of implant failures and biological complications compared to periodontally healthy patients. This summarized gathering of evidence demonstrates that the risks associated with periodontitis are of present concern and the data should encourage stronger emphasis on supportive implant therapies for these patients. It can be concluded that when high-risk patients comply with rigorous and continued supportive therapies, similarly good outcomes can be achieved in periodontitis-susceptible patients as can be achieved in periodontally healthy patients treated with implants.

Tallarico M, Meloni SM, Canullo L, et al. Clin Implant Dent Relat Res. 2015 Oct 7. doi: 10.1111/cid.12380. [Epub ahead of print]

PURPOSE: The aim of the present randomized controlled trial was to compare the 5-year clinical and radiological outcomes of patients rehabilitated with four or six implants placed using guided surgery and immediate function concept.
MATERIALS AND METHODS: Forty patients randomly received four (All-on-4) or six (All-on-6) immediately loaded implants, placed using guided surgery, to support a cross-arch fixed dental prosthesis. Outcome measures were survival rates of implants and prostheses, complications, peri-implant marginal bone loss, and periodontal parameters.
RESULTS: No drop-out occurred. Seven implants failed at the 5-year follow-up examination: six in the All-on-6 group (5%) and one in the All-on-4 group (1.25%), with no statistically significant differences (P = 0.246). No prosthetic failure occurred. Both groups experienced some technical and biologic complications with no statistically significant differences between groups (P = 0.501). The All-on-4 treatment concept demonstrated a trend of more complications during the entire follow-up period. A trend of more implant failure was experienced for the All-on-6 treatment concept. Marginal bone loss from baseline to the 5-year follow-up was not statistically different between All-on-4 (1.71 ± 0.42 mm) and All-on-6 (1.51 ± 0.36 mm) groups (P = 0.12). For periodontal parameters, there were no differences between groups (P > 0.05).
CONCLUSION: The authors concluded that both approaches—All-on-4 and All-on-6—may represent a predictable treatment option for the rehabilitation of complete edentulous patients in the medium term. Longer randomized controlled studies are needed to confirm these results.

Current strategies for treatment of the edentulous maxilla using implants for fixed prostheses include the use of as few as four implants. This study confirms that four-implant strategies are successful at the implant level. The management of these large prostheses requires intervention to address various complications. Over the longer term, the burden of biologic and prosthetic complications may distinguish four- versus six-implant strategies. This current comparison shows that a four-implant strategy is a viable concept to support full-arch maxillary treatment. Careful prosthetically driven treatment utilizing a guided surgery procedure may have contributed to the positive outcomes.

Bezerra Ferreira JD, Rodrigues JA, Piattelli A, et al. Clin Oral Implants Res. 2015 Sep 26. doi: 10.1111/clr.12705. [Epub ahead of print]

OBJECTIVE: This study evaluated the effect of cigarette smoking on the percentage of early bone-to-implant contact (BIC%), the bone density in the threaded area (BA%) as well as the bone density outside the threaded area (BD%) around micro-implants with sandblasted acid-etched surface retrieved from human jaws.
MATERIAL AND METHODS: Twenty-two subjects (mean age 55.4 ± 4.5 years) were divided in two groups: smokers (n = 11 subjects) and never-smokers (n = 11 subjects). Each subject received one micro-implant during conventional mandible or maxilla implant surgery. After 8 weeks, the micro-implants and the surrounding tissue were removed and prepared for histomorphometric analysis.
RESULTS: Two micro-implants placed in smokers showed no osseointegration. Early stages of maturation of the newly formed bone were present, mainly in the never-smokers. Marginal bone loss, gap, and fibrous tissue were present around some implants retrieved from smokers. Histometric evaluation indicated that the mean BIC% ranged between 25.9 ± 9.1 and 39.8 ± 14.2 for smokers and non-smokers, respectively (P = 0.02). Smokers presented 28.6 ± 10.1 of BA% while never-smokers showed 46.4 ± 18.8 (P = 0.04). The mean of BD% ranged between 19.1 ± 7.6 and 28.5 ± 18.8 for smokers and never-smokers, respectively (P = 0.21).
CONCLUSION: Cigarette smoking has a detrimental effect on early bone tissue response around sandblasted acid-etched implant surface topographies.

Previous studies have indicated tobacco smoking as a risk factor in early peri-implant bone healing. Tobacco is composed of a range of different toxins known not only to reduce blood flow and nutrient delivery to the surgical site but also to inhibit cell proliferation, induce hypoxia, impair oxygen delivery to the peri-implant tissue, and decrease bone density. Advances in implant surface development have, to some extent, helped to overcome problems with early implant failures in smokers. However, this study confirms earlier results with lower bone-to-implant contact and lower bone density for smokers even around rough implant surfaces. With disregard to implant surface type, smoking increases the risk for complications with implant treatment. Patients should be encouraged to stop smoking before implant therapy. Smoking habits must be considered a key risk factor in developing a comprehensive risk profile for individual patients.