Screw- Versus Cement-Retained Implant Restorations: Methods

Objectives:

To evaluate the factors associates with long-term implant survival in a large cohort of patients in regular follow-up until data collection.

Methods:

The study population consisted of 475 patients who were referred to a private clinic limited to Periodontics and Implantology between November 1995 and july 2006. Data were collected from patients files with regards to smoking habits, periodontal condition, diabetes mellitus, implant survival, and time when implant failure occurred. Patients were divided into those who participated in the clinic and those who participated in a supportive periodontal program in the clinic and those who only attended the annual free-of-charge implant examination.

Results:

A total of 1626 implants were placed with a follow-up ranging from 1 to 114 months (Average 30.82-+ 28.26 months). Overall,77(4.7%) implant were lost in 58 (12.2%) patients after a mean period of 24.71 -+ 25.84 months. More than one-half of the patients (246; 51.7%) participated in a structured supportive periodontal program in the clinic, and 229 (48.3%) only attended to the annual free-of-charge implant examination. Smoking and attendance in a regular supportive periodontal program were statistically associated with implant survival. Patients with (treated) moderate-to advanced chronic periodontal disease demonstrated higher implant failure rates but, this difference did not reach statistical significance. Diabetes mellitus was not related to implant survival in this patients cohort.

Conclusions:

Smoking and attendance in a regular supportive periodontal program were found to be strongly related to implant survival. Special attention should be given to continuous periodontal supportive programs to implant patients.(Implant Dent 2010;19:57-64)

Discussion:

An implant-supported restoration offers a predictable treatment for tooth replacement. Nevertheless, failures that mandate immediate implant removal do occur. The consequences of implant removal jeopardize the clinician’s efforts to accomplish satisfactory function and esthetics. For the patient, this usually involves further cost and additional procedures.

Reported predictors for implant success and failure are generally divided into patient-related factors(e.g., general patient health status, smoking habits, quantity and quality of bone, and oral hygienic maintenance), implant characteristics (e.g., dimensions, coating, and clinician experience.

The overall first-year survival rate for dental implants is between 92% and 97% An additional 1% of all implants that are initially successful and rehabilitated are lost every year because of complications. In this study, the survival rates fall between the reported survival rates in the literature.

Hultin et al4 conducted a study that systematically reviewed whether supportive implant treatment during a follow-up of at least 10 years after functional loading is effective in preventing biological complications and fixture loss. It was concluded that, to date, there are few available studies that evaluate the long-term effect of supportive programs for implant patients and that there is an urgent need for such studies to be initiated. This report clearly illustrates that there is an important role for regular continuous supportive periodontal therapy in implant patients to increase implant survival over time. In the treatment strategies for periodontitis, the need for supervised training and reinforcement of self-performed oral hygiene is well established.

Also, in dental implant patients, instruction in brushing and interproximal cleaning should be initiated as soon as the prosthetic reconstruction is connected. In an elderly patients, reduce capacity of diligence and manual dexterity is not uncommon, thus requiring frequent professional training visits and cleaning of abutment surfaces to remove bacterial biofilms. Although there is no direct evidence in the literature to suggest the importance of supportive therapy for implants as for periodontally treated teeth, periodontal therapy has been suggested to precede implant therapy in partially dentate patients, whereas systematic and continuous monitoring of the periodontal and peri-implant tissue conditions is suggested to prevent recurrence of periodontal disease and allow early diagnosis and treatment of peri-implant disease.

Other environmental- and patient-related factors contribute to implant failures. Nitzan et al21 report a relationship between marginal implant bone loss and smoking habits. A higher incidence of marginal implant bone loss was found in the smoking group, which was more pronounced in the maxilla. A higher degree of complications, or implant failure rates, were found in smokers with and without bone grafts. However, in an 18-month study of 1183 implants, kumar et al24 report similar survival rates (97% and 94.4%) for smokers and nonsmokers. In this study, smokers exhibited a significantly lower survival rate than nonsmokers. Smokers undergoing both implant-related surgical procedures and dental implantation should be encouraged by their dentists, oral and maxillofacial surgeons, or treating physicians to cease smoking, emphasizing that smoking can increase complications and reduce the success rate of these procedures.

Successful osseointegration has been shown in patients with different types of periodonitis. However these reports do not offer comparative data between periodontally healthy patients. Nevertheless, a systematic review by vam der weijden et al 27 conclude that the outcome of implant therapy in periodonitis patients may be different compared with individuals without such a history in terms of loss os supporting bone and implant loss.

In a systematic review of implant outcomes in treated periodonitis subjects, Ong et al20 conclude that there is some evidence that patients treated for periodonitis may experience more implant including higher bone loss and peri-implantitis than nonperiodontitis patients. Evidence was stronger for implant survival than implant success. In this report, periodontal disease patients demonstrated higher implant failure rates but this differences did not reach statistical significance, which could be attributed to the fact that the patients were treated in a periodontal clinic and their periodontal condition was ‘’controlled.’’ Consequently, appropriate consent should be obtained before implant therapy is provided to periodontal patients.

Diabetes mellitus is one of the most commonly encountered contraindications to dental implant therapy Glycemic control is viewed as a critical variable in identifying whether patients with diabetes are eligible for implant therapy. This view on the importance of glycemic control in implant success has been reinforced. Several clinical reports suggest that in patients with ‘’well-controlled’’ type 2 diabetes mellitus, dental implant success rates (92%-100%) may not be significantly compromised. In addition, a large multicentre study of dental implant success report an implant failure rate of only 7.8% for 255 implants placed in “selected” patients with type 2 diabetes mellitus.

The hypothesis that patients with diabetes are appropriate candidates for implants and that compromises in glycemic control may not been explored. This study found no evidence of diminished clinical success or significant early healing complications associated with implant therapy in patients with controlled type 2 diabetes mellitus, which agrees with the former study.

CONCLUSIONS:

Smokind and attendance in a regular supportive periodontal program were found to be strongly related to implant survival. It is highly recommended to maintain implant patients under a strict supportive periodontal treatment protocol that might contribute to implant survival.

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