Dental Implants in the Diabetic Patient -- A Retrospective Study

By Thomas J. Balshi, DDS, PhD, FACP
and Glenn J. Wolfinger, DMD, FACP

Implant Dentistry / Volume 8, Number 4 - 1999. Page 355.

Abstract
It has become increasingly common for controlled diabetic patients to be considered as candidates for dental implants. This study reports on the results of placing implants in 34 patients with diabetes who were treated with 227 Bränemark implants. At the time of second-stage surgery, 214 of the implants had osseointegrated, a survival rate of 94.3 percent. Only one failure was identified among the 177 implants followed through final restoration, a clinical survival rate of 99.9 percent. Screening for diabetes and trying to ensure that implant candidates are in metabolic control are recommended to increase the chances of successful osseointegration. Antibiotic protection and avoidance of smoking also should be considered.

Key Words: dental implants, diabetes, osseointegration, implant prosthesis.

Implant Dentistry / Volume 8, Number 4 - 1999. Page 355.

TABLES

Introduction
Diabetes mellitus is one of the world's major chronic health problems. In the United States alone, this metabolic disorder affects an estimated 15.7 million individuals, 5.9 percent of the population1. Among men and women over 65 years of age, where the rates of edentulism are highest, an estimated 18.4 percent of all individuals have some form of the disease.
A complex syndrome with more than one cause, diabetes is responsible for numerous complications affecting the whole body. In the oral environment, it has been associated with xerostomia, increased levels of salivary glucose, swelling of the parotid gland, and an increased incidence of caries2. Adult diabetics also experience a 2.8 to 3.4 times higher risk of developing periodontitis than nondiabetics3. Although there has been some conflicting evidence, diabetic patients appear to be more prone to infection4-6. Healing after surgery in the diabetic patient appears to occur more slowly, exposing the tissues to complications such as tissue necrosis7. Furthermore animal studies indicate that streptozotocin-induced diabetes interferes with the process of osseointegration8,9.
Because of such considerations, diabetes has sometimes been considered a contradiction for the use of dental implants. The 1988 National Institutes of Heath Consensus Development Conference Statement on Dental Implants stopped short of explicitly stating this but did include "debilitating or uncontrolled disease" and "conditions, diseases, or treatment that severely compromise healing" among its list of contraindications for dental implants10.
Tempering concerns about the increased risk of implant failure in the diabetic patient, however, has been the growing awareness of the benefits provided by modern dental implants. First developed in the 1960s and commercially introduced 20 years later, implants represent a significantly better solution for tooth loss replacement than traditional dental appliances. Because they are anchored directly into bone, they provide complete stability, in contrast to traditional tooth-replacement alternatives such as dentures. They also minimize bone resorption and atrophy, which can cause facial collapse and the resultant appearance of premature aging. Five-year survival rates of more than 95 percent in studies of implants supporting mandibular overdentures have become common11,12, and research has demonstrated improved masticatory function and overall satisfaction in implant patients13,14.
Since 1982, the worldwide market for dental implants has grown to approximately $450 million. A 1998 trend survey in the trade journal Dental Products Report reported that more than 50 percent of oral surgeons and periodontists reported placing more implants in 1997 than in the prior year.
At the same time, as techniques for managing diabetes have evolved, evidence has accumulated that diabetic patients who effectively control their disease incur a lower risk of various health complications than their uncontrolled cohorts. Well-controlled diabetics, for example, have been demonstrated to respond well to periodontal therapy and have fewer systemic complications than poorly controlled diabetics15. Before exogenous insulin was widely available, the caries incidence in diabetics was high, but since insulin therapy has become commonplace, most studies have failed to demonstrate an increased caries incidence in treated patients2. Similarly, rates of infection appear to be worse in uncontrolled diabetics5.
Awareness of such distinctions has resulted in a greater degree of openness to the notion that diabetic patients may be good candidates for dental implants. A few studies have directly addressed this question in recent years and yielded promising preliminary data. Kapur et al in 1998 compared 37 diabetic patients who received conventional removable mandibular overdentures versus 52 who were fitted with implant-supported ones and concluded that implants can be successfully used in diabetic patients with even low to moderate levels of metabolic control16. A 1994 study found a 92.7 implant success rate for Type II diabetic patients under acceptable glucose control17.
This article reports on results obtained by the authors after placing 227 implants in 34 diabetic patients.

Methods and Materials
The study population (Table 1) included 17 males and 17 females ranging in age from 34 to 79. The average age was 62.1 (standard deviation equaled 11.4). Two of the subjects, both male, were smokers. Diabetic status for the most part was determined from patient health histories or personal interviews. All patients were questioned about how their disease was being treated, and all were urged to strive for optimal metabolic control at the time of implant placement. In addition, a ten-day course of wide-spectrum antibiotics was begun for all subjects on the day of surgery.
Between April, 1987 and May, 1998, the study subjects were treated with a total of 227 implants, an average of 6.7 per person. Table 2 shows the anatomic distribution. Virtually all of the fixtures placed were Bränemark System implants. Implant lengths ranged from 7.0 to 20.0 mm. Approximately 190 were between 10 and 18mm long. Table 3 details the distribution of implants by length.
Of the 227 total implants, 91 were placed in fresh extraction sites. The remaining 136 implants were placed in osteotomies created by standard drilling techniques.
Four of the 227 implants were loaded immediately after placement, all in the same patient. This individual simultaneously was fitted with 11 other implants that were not immediately loaded.
Bone grafting was utilized at 31 of the 227 sites.
Thirty of the original 34 patients were followed through uncovering and final restoration of 177 implants. The healing period between the first and second-stage surgeries ranged from 0 to 15.5 months, with 5.9 months being the average healing period per implant.

Results
Upon uncovering, 214 of the 227 implants were found to have osseointegrated, a success rate of 94.3 percent. Of the thirteen failed implants, four occurred in each of two patients (both non-smokers), two occurred in one patient (also a non-smoker), and one occurred in each of three patients. Of the latter, one was a smoker.
Of the four implants that were loaded immediately18, three failed. In the same patient, a second implant that was not immediately loaded also failed.
Six of the 13 surgical failures were located in the posterior mandible, four were in the posterior maxilla, two were in the anterior maxilla, and one was in the anterior mandible. Table 4 summarizes the location, diameter, length, and healing period of all the failed implants.
Of the 31 grafted sites, one (3.2 percent) failed. Autogenous bone, Grafton Gel, and a membrane also were employed at this site.
Of the 177 implants that were followed through final restoration, one failure was identified, a failure rate of only .06 percent. This implant, which was initially placed in a grafted site in the left maxilla and restored five months later, had a 3.75mm diameter and a length of 10mm. The cause of the failure appeared to be occlusal overload caused by bruxism.
Table 5 summarizes the results achieved by the patients at each stage.

Discussion
Although the results of this study indicate that excellent results can be obtained when Bränemark implants are placed in diabetic patients, certain precautionary measures can increase the likelihood of a successful outcome.
1) Adequate screening is essential. A comprehensive health history should be obtained from every candidate for implant therapy, with attention given to fundamental systemic problems. If the patient has a history of diabetes, additional information should be gathered about his or her current treatment.
2) If the diabetic patient's metabolic control appears to be clinically inadequate, implant therapy is best delayed until better control is achieved.
3) The doctor should stress to the patient the importance of taking all diabetic medications on the days of surgery and maintaining an acceptable level of metabolic control throughout the healing period.
4) A ten-day regime of broad-spectrum antibiotics should be begun on the day of surgery to reduce the risk of infection.
5) The deleterious impact of smoking on osseointegration has been well documented19. Although the results of this study suggest that diabetics who smoke can experience success with dental implants, the authors believe that the combination of smoking and diabetes may substantially increase the risks of implant failure. For that reason, diabetic patients who smoke should be urged to enter a smoking cessation program before implant surgery.

Conclusion
Dental implants offer significant benefits that make them of interest to a wide spectrum of patients, including the growing number of individuals with diabetes mellitus. Although uncontrolled diabetes has been shown to interfere with various aspects of the healing process, the results of this retrospective study indicate that a high success rate is achievable when dental implants are placed in diabetic patients whose disease is under control.


References
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