One-Year Clinical Outcome of Dental Implants Placed in Patients With Type 2 Diabetes Mellitus: A Case Series

Abstract

Purpose: 

Diabetes mellitus is a prevalent medical disorder. It is often accompanied with systemic adverse sequelae, such as wound healing alterations, which may affect osseointegration of dental implants. The use of dental implants in patients with diabetes mellitus remains controversial because altered bone healing around implants has been reported. The purpose of this study was to present 1-year clinical outcomes of 23 implants placed in 10 patients with well-, or moderately well, controlled type 2 diabetes mellitus.

Materials: 

All implants were uneventfully placed in the mandible or maxilla. Three different types of definitive implant-supported prostheses, cement- or screw-retained fixed dental prostheses, and overdentures were delivered to the patients.

Results: 

At 1-year follow-up recall, no implants were lost, and 0.3 ± 0.2 mm marginal bone loss was noted. No periapical radiolucencies, no bleeding on probing, or pathologic probing depth were recorded at these recalls.

Conclusion: 

This clinical report supports the use of dental implants in patients with well-, or moderately well, controlled type 2 diabetes mellitus as a dental treatment modality. No evidence of diminished clinical success or significant complication related to implant treatment was found for this patient population.

The prevalence of diabetes is high and increasing dramatically.¹ It has been predicted that the number of patients with diabetes mellitus worldwide will increase from an estimated 135 million in 1995 to 300 million in 2025.² Diabetes mellitus is the most prevalent endocrine disease affecting 5% to 10% of the overall population. It is diagnosed when fasting plasma glucose reaches or exceeds 126 mg/dL. Diabetes mellitus occurs in 2 types. Type 1 diabetes mellitus (insulin-dependent diabetes mellitus) is caused by the autoimmune destruction of β cell, which results in partial or complete insulin deficiency. Type 2 diabetes mellitus (non-insulin–dependent diabetes mellitus) is characterized by variable degrees of insulin resistance in peripheral tissue, impaired insulin secretion, and increased glucose production. It arises in response to genetic and environmental factors.³ Type 2 diabetes mellitus represents approximately 90% of the total diabetic patients.¹

Poorly controlled diabetes mellitus is associated with systemic adverse sequelae such as increased susceptibility to infection, delayed wound healing, and microvascular complications. Diabetic patients were rejected from dental implant therapy for a long time because of concerns related to healing.^1,4 To date, the use of dental implants in diabetic patients is controversial.⁵ Although it is generally accepted that patients with controlled diabetes mellitus have similar success rates for dental implants compared with healthy people,^6,7 several reports have shown contradicting results.⁸ Therefore, factors influencing successful implant therapy for patients with diabetes mellitus still remain in question, specifically with limited information available on the influence of glycemic control on implant success.⁹

There are limited and controversial data available in the dental literature regarding the clinical outcome of implant treatment for patients with diabetes mellitus.^1,6,9–11 In this clinical report, 1-year clinical results of 23 implants placed in10 patients with type 2 diabetes mellitus were presented.

Patients and Methods

Ten patients with type 2 diabetes mellitus suffering from various degrees of edentulism and requesting implant treatment were retrospectively evaluated for this study. Preoperative planning included a medical history and information such as diabetes duration, type of medication used to control diabetic condition, frequency of glucose monitoring, and any complication related to diabetes (eg, retinopathy, macrovascular complications) was noted. The patients' laboratory test results regarding HbA1c (glycosylated hemoglobin), fasting plasma glucose, cholesterol, blood lipids data were obtained preoperatively, and a consultation with their physicians was done. The inclusion criteria were (1) a diagnosis of type 2 diabetes mellitus, (2) partial or fully edentulism and request for implant therapy, (3) an HbA1c values ≤10% during the perioperative period, and (4) control of periodontal disease, if present, before implant placement. Patients with type 2 diabetes mellitus could be on a modified diet or receiving oral medication, insulin, or combination therapies. An HbA1c value ≤8.0% represents a well-controlled type 2 diabetes while an HbA1c value from 8.1% to 10.0% represents a moderately controlled type 2 diabetes.⁹

A total of 23 dental implants (Astra Osseospeed, Astra Tech, Molndal, Sweden) were placed in 10 patients with type 2 diabetes in the implant clinic in 2007 and 2008 (Table 1). At the time of implant placement, the mean age of the patients was 58 ± 9 years (range, 45 to 71 years). Each patient signed an informed consent before implant placement. All implants were placed according the manufacturer's instructions. A traditional 2-stage surgical protocol was used for implant placement. The surgical procedure consisted of a local anesthesia with or without intravenous sedation. A crestal incision was made followed by a full-thickness mucoperiosteal flap elevation. After the implant sites were prepared, all implants were placed using a torque controller (Fig. 1). The final insertion torque values recorded during the implant placement in this study were 35, 40, or 45 N·cm. The mucosa was sutured after the implant placement. All patients received postoperative antibiotic treatment (500 mg amoxicillin and clavulanate potassium twice a day for 5 days). Also, a mouth rinse including 0.2% chlorhexidine was prescribed to the patients starting the day after the surgery and continued for 2 weeks. The implants were left to heal 3 months in the mandible and 6 months in the maxilla for osseointegration. At the second surgery, the healing abutments were placed on top the implant body after the cover screws were removed (Fig. 2). Final impressions were made, and the implant-supported definitive dental prostheses were fabricated using traditional dental methods (Fig. 3).

Table 1: Overview of Data Related to Patients and to Implants Placed in This Study

Fig. 1.: After flap elevation, 3 implants were placed using a surgical guide. High primary stability was achieved during the implant placement.

Fig. 2.: Intraoral view of healing abutments and soft tissue before final impression. The soft tissue with pale pink color was healthy.

Fig. 3.: Periapical radiograph of implants and screw-retained restoration after 1 year. Almost no marginal bone loss was noted around the implants.

The patients were recalled at 1 week and at 3, 6, and 12 months after the implant placement. Implant success was based on the following criteria suggested by Misch et al.¹²

Results

No implants were lost at 1 year after the implant placement. All implants were stable. Mean marginal bone loss of 0.3 ± 0.2 mm was observed during the follow-up period, as determined by digital periapical radiographs. Marginal bone changes were measured in a computer using image analysis software, by 1 examiner, using the implant-abutment junction as a reference. No periapical radiolucencies, no bleeding on probing, or pathologic probing depth were recorded at these recalls. All implants were considered successful at the 1-year follow-up.

Discussion

Infection in clean wounds is more likely to occur in diabetic patients compared with patients without diabetes mellitus. Poorly controlled diabetic patients present more difficult management problems.^4,7 Postponement of surgical procedures has been recommended until optimum glucose and protein levels are obtained and maintained.¹³ Bacterial infection and occlusal overload are the most common factors causing implant failures.^14,15 Peri-implantitis that may cause implant failure exhibits clinical signs similar to those found around periodontally diseased teeth.^16,17 These signs can be considered as bleeding, suppuration, pain, mobility, increased probing depth, radiographic evidence of bone loss, and presence of bacteria.^4,7,15 Morris et al,¹⁸ found that the survival of implants placed with preoperative antibiotics was 4.5% higher than implants placed without antibiotic coverage at implant placement. It has also been reported that the use of chlorhexidine before and after implant placement provided better outcomes in patients with type 2 diabetes.¹⁸ Therefore, postoperative antibiotics and chlorhexidine rinsing were used to reduce complications in the patients described in this report.

It has been reported that uncontrolled diabetes may impair wound healing, which may affect osseointegration of dental implants. The influence of diabetes on the survival of dental implants has been analyzed in animal studies.^3,19 Hasegawa et al³ [T1], histologically and histomorphometrically examined bone healing around the implants in the type 2 diabetes rat model. They found that bone volume around implants was consistently smaller for the diabetes group than for the control group in the cortical area. They also observed that bone-implant contact percentage was considerably lower for the diabetes group in both the cortical and marrow areas. Iyama et al,¹⁹ found that the bone formation around a hydroxyapatite implant away from the endosteum and periosteum was suppressed in the diabetic model.

As mentioned in the introduction section, the use of dental implants is controversial in patients with type 2 diabetes. There are few reports regarding the clinical outcome of implant treatment for patients with diabetes mellitus.^1,6,9,11 Tawil et al,¹ placed 255 implants in 45 patients with type 2 diabetes mellitus (mean perioperative HbA1c level of 7.2%) and followed these patients for 1 to 12 years. They reported that the overall survival rate was 97.2% for the diabetic group and 98.8% for the control group. There was no significant difference for age, gender, diabetes duration, smoking, or type of hypoglycemic therapy. Olson et al⁶ placed 178 implants and reported that the overall survival rate was 88% from prosthesis placement through the 60-month follow-up in 58 patients. Dowell et al⁹ evaluated 50 implants in 35 patients in whom the HbA1c levels ranged from 4.5% to 13.8%. They reported that all 50 implants placed were osseointegrated at the abutment connection, which was 4 months after the implant placement. Bugea et al¹¹ placed 3 implants in the anterior mandible to support an overdenture in a patient with type 2 diabetes mellitus. One of the implants, which was osseointegrated, was removed 2 months after the implant placement because its position was prosthetically unfavorable. They histologically evaluated the implant after it was removed and found that bone-to-implant contact was 80%, meaning successful osseointegration.

It has been reported that high primary implant stability, which is 32 N·cm or above, is one of the prerequisites to achieve osseointegration.²⁰ It has been considered that the high insertion torque values recorded (35, 40, or 45 N·cm), and 2-stage surgical approach, and conventional loading protocol used in this study might have resulted in an implant success rate of 100%. Although Brånemark et al²¹ suggested healing periods of 3 to 6 months for the mandible and maxilla, respectively, the length of healing time to achieve osseointegration has not been established for patients with diabetes. Future clinical studies may be helpful to establish appropriated healing times in patients with diabetes.

Conclusion

It has been concluded that because no evidence of diminished clinical success and/or significant complications related to implant treatment were observed for this patient population, dental implant treatment can be offered to patients with well- or moderately controlled type 2 diabetes mellitus. Further studies including a greater number of patients are needed to understand better the relationship between type 2 diabetes mellitus and osseointegration.

Disclosure

The author has no conflict of interest. No special relationship between company and author exists.