Heeje Lee D.D.S.
Conventional implant loading for mandibular removable prosthesis and maxillary fixed prosthesis ranked highest for implant and prosthesis survival rates, while most of the immediate loading groups ranked lower in those categories.
In patients with at least one edentulous arch, based on different loading protocols, what is the current level of evidence for implant and prosthodontic survival rates?
The authors searched four electronic databases for trials published up to 2008. They also hand searched journals and systematic reviews. Their search was limited to clinical trials that investigated the compatibility of different loading protocols with the achievement of osseointegration. Minimal follow-up period was 12 or more months. They included all levels of evidence except expert opinions. Case series were accepted if more than 10 subjects were included. The initial search yielded 295 articles for full-text reading, from which 61 articles were selected for review. Only 6 were RCT. Those articles were stratified by type of prosthesis, loading protocol, implant jaw location and prosthodontic design. The authors evaluated the selected studies based on study design, sample size and outcome homogeneity. Validation criteria were specifically created based on evidence level, number of included studies, and homogeneity among them. However, the authors did not provide justification for these criteria.
The authors formed groups stratified by implant loading protocols (conventional, early, immediate loading, and immediate loading of immediately placed implants), prosthodontic designs (removable and fixed), and arch locations (maxilla and mandible). Only two of the groups were ranked as "scientifically and clinically validated" for the 1) conventional loading of implant overdentures in the edentulous mandible, the implant survival rates (one to 10 years) ranged from 97.1 percent to 100 percent, and the denture survival rates ranged from 88 percent to 100 percent; 2) for the conventional loading of fixed implant prosthesis in the edentulous maxilla, the implant survival rates (three to 10 years) ranged from 95.5 percent to 97.9 percent and the denture survival rates ranged from 96.3 percent to 100 percent.
Only conventional loading for mandibular overdenture and maxillary fixed prosthesis were ranked as "scientifically and clinically validated". Immediate loading of immediate placed implants was ranked as "clinically insufficiently documented" except for maxillary fixed prosthesis, which was ranked as "clinically documented". Most of the remaining groups were ranked as either "clinically well documented" or "clinically documented".
Source of Funding:
None of the authors reported a conflict of interest.
Importance and Context:
To reduce the healing time for implant treatment, modified implant loading protocols have been proposed. Many factors such as maxillary location of the implants, type of prosthodontic rehabilitation, implant surface and timing of the prosthodontic reconstructions are thought to influence the success of implant/prosthesis combinations.
Strengths and Weaknesses of the Systematic Review:
The authors searched multiple databases. They also hand searched materials, but only in offline journals. They did not provide information about the number of reviewers involved and whether they used language restrictions. They failed to describe their selection process. In order to rank the level of evidence inside the groupings, the authors proposed new evaluation criteria. But, these criteria were not validated. They did not perform meta-analysis nor offered an explanation for that omission. Also it was found that a group was automatically given a higher level of validity according to the criteria because it included a randomized clinical trial (RCT) even though the RCT was for investigating the implant survival rate not based on loading protocol but some other variables.
Strengths and Weaknesses of the Evidence:
Since the validity of the new criteria was debatable as described above, the level of support for the conclusions from the current systematic review would be considered poor.
Implications for Dental Practice:
Although the SR concluded that conventional implant loading for mandibular removable prosthesis and maxillary fixed prosthesis were the highest ranked with respect to implant and prosthesis survival rates, while most of the immediate loading groups were ranked lower in those categories; there were significant concerns about the group classification methodology as well as the available evidence. Putting these concerns aside it can be argued that for the immediate loading protocol, stringent case selection would be the most important factors for success.