Candice McMullan-vogel D.D.S., Dr. med. dent.
It is still not clear when sinus augmentation is necessary for implant therapy or which technique is most clinically effective.
Among patients with an edentulous posterior maxillary and with insufficient bone volume is sinus augmentation necessary for maxillary posterior implant therapy? If so, which is the most effective sinus augmentation technique?
The authors included randomized controlled clinical trials (RCTs) of either parallel group or split-mouth design. To be included, the patients had to present with missing teeth and an atrophic posterior maxilla possibly requiring augmentation of the maxillary sinus before or during dental implant placement. The authors evaluated any bone augmentation technique, active agent or biomaterial used with osseointegrated, root-formed dental implants. Outcome measures included prosthesis, implant or augmentation procedure failure; major complications at the treated/augmented and/or bone donor sites; bone gain; and patient satisfaction. The authors conducted an all-language search of four databases and several relevant dental journals for articles published through January 2010. They used a variety of methods (contacting RCT authors, selected researchers, and dental implant manufacturers; as well as searching RCT and review bibliographies) to identify unpublished or ongoing RCTs. Study eligibility screening, data extraction, and risk of bias assessment were conducted independently and in duplicate with disagreements resolved by discussion and third author consultation if needed.
The authors judged 10 RCTs including 250 patients, using different techniques and materials. One trial including 15 patients evaluated whether 5-mm–long implants with a diameter of 6 mm could be an alternative to sinus lift in bone having a residual height of 4 to 6 mm. The remaining nine trials with 235 patients compared different sinus lift techniques and, of these, four trials with 114 patients, evaluated the efficacy of platelet-rich plasma (PRP). Since the authors evaluated numerous techniques, they only were able to conduct meta-analyses for trials evaluating the efficacy of PRP. They did not observe statistically significant differences for any of the evaluated interventions.
These conclusions, based on 10 trials of mostly small size and short follow-up, should be viewed as preliminary and interpreted with caution. It is unclear when sinus lift procedures are necessary. Five-mm short implants can be successfully loaded in maxillary bone with a residual height of 4 to 6 mm, but their long-term prognosis in unknown. Elevating the sinus lining in the presence of 1 to 5 mm of residual bone height without the addition of a bone graft may be sufficient to regenerate new bone to allow rehabilitation with implant-supported prostheses. Bone substitutes might be successfully used as replacements for autogenous bone, with less risk to the patient. If the residual alveolar bone height is 3 to 6 mm, a crestal approach to lift the sinus lining and placement of 8-mm implants may lead to fewer complications than a lateral window approach and placement of implants that are 10 mm or longer. Current evidence does not show that PRP treatment improves the clinical outcome of sinus lift procedures with autogenous bone or bone substitutes.
Source of Funding:
School of Dentistry, The University of Manchester, UK; The Health Foundation, UK; Swedish Medical Research Council, Sweden.
Importance and Context:
Insufficient bone volume is a common problem encountered in restoring the edentulous posterior maxilla using implants. Sinus augmentation procedures, which increase bone volume using autogenous bone and/or biomaterials, may be widely performed despite the lack of evidence for improvement in treatment prognosis or patients’ quality of life. Although several systematic reviews have been published on sinus lift procedures, many of those findings were not based on reliable clinical studies and presented histological data only, which can be misleading.(1,2,3,4,5,6,7,8)
Strengths and Weaknesses of the Systematic Review:
The authors used exhaustive measures to locate and identify RCTs and collect and analyze data. They followed a standardized protocol of risk assessment for each trial. Although three review authors are among the authors of four included trials, they were not involved in the quality assessment of those trials. The authors critically discuss each trial and provide clinically relevant information that the practicing clinician should consider when evaluating sinus augmentation procedures.
Strengths and Weaknesses of the Evidence:
Although the authors initially identified 29 potentially eligible trials, they excluded 19 trials for a variety of reasons, the most frequent of which was the presentation of only histological data (13 trials). Small sample sizes make it difficult to clearly demonstrate differences in treatment efficacy. Additionally, the included studies do not provide evidence of long-term treatment benefit. Six of ten included studies were judged to be at high risk of bias, and the same number received funding from the manufacturer of the product being tested. Meta-analysis was only possible with three trials evaluating platelet-rich plasma.
Implications for Dental Practice:
Although the included RCTs reported clinically relevant, patient-oriented outcomes and provide information that the clinician can critically evaluate when deciding whether to perform sinus augmentation or which procedure to use, the identified high risk of bias should be considered when extrapolating the results clinically. In addition, the impact of the procedure being delivered by more or less experienced, skillful clinicians was not evaluated.
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