A retrospective study to compare improvement of implant maintenance by Medical Treatment Model.

BACKGROUND: Study comparing the improvement of implant maintenance is limited. Clinicians must be aware of implant maintenance to improve long-term success of implant. AIMS: The aim of this retrospective study was to evaluate whether the Medical Treatment Model (MTM), which is a comprehensive treatment, includes initial risk assessment, lifestyle instructions, such as diet and habits, and a customized maintenance program to improve implant prognosis.
MATERIALS AND METHODS: Patients who were comprehensively treated were included and divided into two groups, test and control groups. The test group included patients who started treatment with MTM, whereas control group included patients who started treatment without MTM introduction. Moreover, subsequently, compliance with maintenance, occurrence of biological complications, and implant failure were evaluated.
RESULTS: About 199 patients with 515 implants were analyzed in the control group and 38 patients with 59 implants in the test group. In the control and test groups, the percentages of patients in the four compliance categories were, respectively, 73.9% and 89.5% for excellent compliance, 7.0% and 7.9% for good compliance, 14.6% and 0% for fair compliance, and 4.5% and 2.6% for poor compliance. There was a statistically significant difference in the compliance with periodontal and implant maintenance between the test and control groups (P = 0.029).
CONCLUSIONS: Within the limitation of this study, MTM significantly enhanced the compliance of patients treated with implants.

Introduction

Implant treatment has been a first choice for the rehabilitation of missing teeth and the restoration of oral function, but various complications, as biological, technical, and esthetic problems, had been reported.[1234] Because biological complications such as peri-implant disease sometimes result in implant failure, it is important to prevent these complications rather than seek treatment options after they occur.

In periodontal treatment, it has been shown that supportive periodontal therapy (SPT) is effective in maintaining oral health and also in preventing the need for reintervention.[5678] In addition, some authors reported that prognosis of treatment's outcomes depends on the patient's compliance with maintenance. They demonstrated that erratic compliance with SPT posed a greater risk for tooth loss compared with complete compliance.[91011] However, SPT programs vary greatly, which affects patients’ motivation to continue periodical maintenance.[12]

Some studies reported that compliance with maintenance after treatment is significantly related to biological complications such as implant failure and peri-implant disease. A cross-sectional study evaluated the frequencies of peri-implant mucositis and peri-implantitis and their associations with several parameters, such as smoking and compliance, in 89 partially edentulous patients.[13] In that study, the prevalence of peri-implant mucositis and peri-implantitis was 44.9% and 11.2%, respectively, within the observation period of 68.2 ± 24.6 months. Furthermore, significant associations of peri-implantitis with smoking and compliance with maintenance were identified, showing that smoking increased the risk for peri-implantitis, whereas greater compliance decreased the risk. A similar result was obtained in a study that investigated the relation between preventive maintenance and occurrence of complications.[14] This study also reported that the incidence of peri-implantitis in patients with a history of peri-implant mucositis in the 5-year follow-up with and without preventive maintenance was 18.0% and 43.9%, respectively.

A long-term study with a 10-year follow-up demonstrated that the lack of adherence to SPT increased the risk for biological complications and implant failure among periodontally compromised patients.[15] However, one study reported that patients who had one or more osseointegrated implants inserted had a higher rate of compliance with maintenance compared with patients without fixture insertion.[16] Although this study mentioned clearly indicated that periodical maintenance significantly reduces the occurrence of peri-implant disease, very few articles reported effective measures to improve, enhance, and sustain compliance with maintenance. What is the key factor that will motivate and inspire patients to continue with maintenance? During recent decades, Kumagai had developed the Medical Treatment Model (MTM) as a treatment flow; this includes initial risk assessment, lifestyle instructions, such as diet and habits, and a customized maintenance program.[17] The concept was based on the proposal of Bo Krasse that the dental treatment should be achieved from the point of view of the medical treatment.[18] Thus, as a general routine, all patients examine their periodontal risk using software and their risk for caries using a saliva test at the initial visit, except in emergency.[19] In addition, the hygienist performs a basic periodontal examination using dental X-rays and intraoral photographs. After discussion of the treatment plan between the clinician and hygienist, the clinician explains the treatment plan in light of all data obtained at the initial visit. Hygienist advises for improvement of the patient's oral environment and diet according to the periodontal and caries risks. If the patient agrees with the plan, treatment starts with the initial periodontal treatment. After this, a recall orientation is provided and a maintenance program that specifies the maintenance interval and the activities needed for maintenance is customized according to the risks and the person's character.

The aim of this study was to evaluate whether MTM improves patients’ compliance with periodontal and implant maintenance and to investigate correlations between compliance and biological complications.

Materials and Methods

This study included patients who underwent implant treatment between 2000 and 2014 and divided into two groups. The research protocol was approved by the Ethics Committee. Patient included having more than one implant for a fixed prosthesis or overdentures and who were followed for at least 2 years after active treatment. Patients who were not followed for regular evaluation and who underwent MTM intervention during the active treatment or the maintenance phase within 2 years were excluded because patient's behavior would be affected by motivation whether or not MTM was applied.

The following intervention was applied to all patients in the groups: periodontal examinations, standardized intraoral photograph, visual evaluation of risk factors for individuals, such as Oral Health Information Suite (OHIS) and saliva test, regular hygienists, private maintenance room, and comparison between before and after intervention [Table 1].

Table 1

Comparison of maintenance programs between the control and test groups

For evaluation, all patients were recalled at least every 3 months after the last visit. The maintenance interval was defined according to the periodontal and caries risks. At periodontal and implant maintenance, probing pocket depth, and bleeding index were evaluated, and X-rays were taken every 6 months. Ultrasonic or hand scaling and polishing were performed. Root planing and tooth-brushing instruction were also provided when necessary.

Baseline conditions

Information was collected on baseline conditions of the subject population, including maintenance period, gender, age, biological complications of implantation, smoking status, bruxism, diabetes, and history of aggressive periodontitis [Table 2].

Table 2

Patient data

Evaluation of compliance

Compliance was evaluated using two measures according to the frequency and intervals between missed maintenance visits and classified into three levels [Table 3].[20]

Table 3

Results of the compliance analysis

Measure A

Complete compliance: Patients who attended at least 70% of the expected maintenance visits

Erratic compliance: Patients who failed to attend >30% of the expected maintenance visits

Noncompliance: Patients who did not respond to recommendations for maintenance therapy or disappeared completely during the active phase of treatment.

Measure B

Complete compliance: Patients who attended most scheduled maintenance visits

Erratic compliance: Patients who failed to attend a maintenance visit for a minimum of 2 years during maintenance therapy

Noncompliance: Patients who did not respond to recommendations for maintenance therapy or disappeared completely during the active phase of treatment.

Total compliance

Compliance A and B measures were integrated to generate total compliance as follows:

Excellent: Complete compliance on both measures

Good: Combination of complete and erratic compliances

Fair: Erratic compliance on both measures

Poor: Noncompliance on both measures.

Association between compliance and biological complications

The association between compliance and biological complications, such as peri-implant mucositis, peri-implantitis, and implant loss, was investigated from the viewpoints of compliance and intervention [Table 4].

Table 4

Results of the analysis of biological complications and implant failure

The results obtained were summarized and statistically analyzed using IBM SPSS Statistics for Windows, Version 19.0. Armonk, NY. Using Fisher's exact test, comparisons between the test and control groups were made for compliance, biological complications related to implantation, and the effects of the following independent variables (risk factors): smoker (yes/no), bruxism, diabetes, and history of aggressive periodontal disease (yes/no).

In addition, the Chi-square test was used for comparisons of gender proportions and Students’ t-test was used for comparisons of age at the time of implant placement. In each test, data containing missing values were excluded from analysis. Statistical significance was set at P < 0.05.

Results

A total of 199 patients with 515 implants were analyzed, whereas 38 patients with 59 implants were analyzed in the test group. Thus, a total of 237 patients with 574 implants were included in the analysis.

The mean age at implant placement was 47.4 (95% confidence interval [CI]: 46.0–48.8, standard deviation [SD]: ±10.1) years in the control group and 48.8 (95%CI: 45.1–52.6, SD: ±11.4) years in the test group. The mean maintenance period was 30 months in the control group and 30.4 (24–39) months in the test group.

Six patients (3.0%) in the control group and two patients (5.3%) in the test group were smokers. Six patients (3.0%) in the control group and one patient (2.6%) in the test group had bruxism. Three patients (1.5%) in the control group had diabetes, and one in each group had a history of aggressive periodontitis [Table 2].

For the compliance A measure, in the control and test groups, 74.9% and 89.5% of patients, respectively, had complete compliance, 20.6% and 7.9% had erratic compliance, and 4.5% and 2.6% had noncompliance. The two groups did not differ significantly for compliance A (P = 0.135) [Figure 1].

Figure 1

Compliance A in the control and test groups’ patients

For the compliance B measure, in the control and test groups, 79.9% and 97.4% of patients, respectively, had complete compliance, 15.6% and 0% had erratic compliance, and 4.5% and 2.6% had noncompliance. The two groups differed significantly for compliance B (P = 0.009) [Figure 2].

Figure 2

Compliance B in the control and test groups’ patients

When the results for compliance A and B were combined, 73.9% and 89.5% of patients in the control and test groups, respectively, were rated as excellent, 7.0% and 7.9% as good, 14.6% and 0% as fair, and 4.5% and 2.6% as poor. Thus, customized periodontal and implant maintenance significantly increased compliance (P = 0.029) [Table 3 and Figure 3].

Figure 3

Combined compliance in the control and test groups’ patients

Regarding biological complications related to the implants that were placed, peri-implant mucositis was observed in one patient in each group, whereas peri-implantitis was diagnosed in one patient in the test group. Two implants placed in two patients in the control group failed and there was no implant failure in the test group; thus, the implant survival rate was 99.6% in the control group and 100% in the test group. There was no statistically significant difference between the control and test groups in the three complications [Table 4]. There was a significant correlation between implant failure and aggressive periodontitis (P = 0.025) [Table 5].

Table 5

P values of correlations between complication and parameters

Discussion

It has been claimed that maintenance is important for achieving a satisfactory long-term outcome in implant dentistry. In a 10-year cohort study, periodontally compromised patients who did not completely adhere to maintenance had a higher implant failure rate.[15] The authors concluded that supportive periodontal maintenance improves long-term implant survival. In the present study, there was no significant difference in implant survival rate between the control and test groups. This result might be related to the 30-month observation period in this study, which may have been too short to adequately evaluate implant survival. In general, the 5-year survival rate of implants is reported to be approximately 95.5%.[11] This rate is similar to the rates found in the two groups in the present study (99.6 and 100% in the control and test groups, respectively).

In the setting of periodontitis, it has been proposed that periodontal maintenance is necessary for the maintenance of oral health in patients with a history of periodontal disease. However, most studies reported low compliance rates for periodontal maintenance therapy. Novaes et al. reported that 25.2% of 1283 patients evaluated in Brazil did not return for SPT appointments.[12] Wilson et al., in an 8-year study, developed a measure of compliance with periodontal maintenance therapy.[7] They divided their patients into three groups according to the total number of maintenance visits and found that 961 patients had complete compliance. Miyamoto et al. established an innovative measure of compliance in a long-term study.[20] The patients were divided into three groups according to two parameters: actual visits as a percentage of expected maintenance visits and the interval between absences during the maintenance period. They concluded that under both definitions, completely compliant patients tended to have lower percentages of plaque and bleeding.[1120] In addition to these two assessments, total compliance was evaluated by combining the two assessments in the present study. While there was no significant difference in the percentage of maintenance visits when the test group was compared with the control group, there was a significant difference in the absence interval. There was a significant difference between the two groups when the two parameters were combined. This may suggest that the number of visits does not always reflect the degree of compliance. In addition, the period examined was too short to evaluate compliance by measure B. It is recommended that the two parameters used in this study should be used to evaluate patient compliance.

Few studies reported compliance with implant maintenance. demonstrated that patients who had one or more implants tended to be better compliers (88.1% compliant) than those with no implants (64.8%).[16] In the present study, there was a similar total compliance rate with a high percentage excellent compliers, particularly in the group in which MTM was introduced (89.5%). Furthermore, the percentage of excellent compliers in the group with MTM had a significantly higher total compliance rate than the group without MTM. As a result, it is suggested that MTM, including individual risk assessments (OHIS and the saliva test), imaging documentation (dental X-rays and intraoral photographs), and a private hygienist and maintenance room, may improve patient compliance after implant treatment. However, a systematic review that evaluated nine studies on supportive therapy and the longevity of dental implants concluded that there is no available evidence for the indication of the maintenance interval and specific hygiene treatment.[21]

There are many reports on biological complications and implant failure. Berglundh et al. found that the occurrence rate of peri-implant disease was 6.47% in a systematic review of implant complications.[1] Jung et al. reported a 5-year cumulative soft tissue complication rate of 7.1%.[22] Another systematic review reported a biological complication rate of 2.6%.[4] Although the rate of biological complications, including peri-implantitis and mucositis, in the present study totaled 1.2%, lower than in the reviews mentioned above, further long-term observations on this parameter, and on survival rate, are required.

The correlations between some risk factors and biological complications were also analyzed in this study. Interestingly, a significant correlation was found between the history of aggressive periodontitis and implant failure (P = 0.025). Many other studies also reported that a history of periodontal disease is a risk factor for peri-implantitis and implant failure.[23242526] Although bruxism, diabetes, and smoking, which are also known to be risk factors, did not seem to be correlated with implant failure in the present study, further observations are needed.

Conclusions

This study demonstrated that a customized maintenance program that includes individual risk assessments (OHIS and the saliva test), imaging documentation (dental X-rays and intra-oral photographs), and a private hygienist and maintenance room significantly improves patient compliance after implant treatment. However, it was not demonstrated that MTM decreased the rate of biological complications and implant failure. Further long-term observations are required.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.