ADVANCES IN DENTAL PRODUCTS |
THE EFFICACY OF A COUNTER-ROTATIONAL POWERED TOOTHBRUSH
IN THE MAINTENANCE OF ENDOSSEOUS DENTAL IMPLANTS
RICHARD S. TRUHLAR, D.D.S.,
HAROLD F. MORRIS, D.D.S., M.S. and
SHIGERU OCHI, PH.D.
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ABSTRACT
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Background. Although most patients with implants have lost their natural teeth because of poor oral hygiene, limited data exist to guide practitioners in their recommendations of home-care regimens for their patients’ endosseous dental implants and maintenance of peri-implant soft-tissue health. The authors conducted a study to compare the home-care effectiveness of a counter-rotational powered toothbrush with that of conventional home-care regimens.
Methods. Before starting the six-year study, the authors trained 85 clinical investigators at 32 dental research centers across the United States in gathering periodontal data. Data for 2,966 implants were entered into a centralized database. Outcomes were derived from 24-month observations of a subset of the implants studied.
Results. Repeated-measures analysis of the toothbrushing methods used on 2,966 implants showed that the counter-rotational powered toothbrush removed plaque significantly better than manual methods (P < .0001 Wald statistic) from all implant surfaces and at all recall intervals up to 24 months. Similar results were demonstrated for the gingival index.
Conclusions. The counter-rotational powered brush appears to be well-suited for home-care regimens aimed at maintaining optimal peri-implant soft-tissue health in patients with dental implants.
Clinical Implications. The importance of maintaining the health of the peri-implant tissues is well-recognized by the dental profession. The counter-rotational powered toothbrush is an effective tool in meeting the oral hygiene challenges associated with implant prosthesis maintenance.
Maintenance of good oral hygiene in patients with dental implants may be challenging, because the caries or advanced periodontal disease that caused the loss of their natural teeth usually resulted from oral hygiene neglect.1 Part of the problem may be related to the methods and tools patients choose. For instance, a key component of optimal plaque control is access to interproximal sites. Traditional manual methods for interproximal plaque removal (such as floss, end-tuft brushes, interproximal brushes and toothpicks) remain the clinical standard because tests of alternatives—in the form of electric toothbrushes—have produced equivocal results.2,3 Meanwhile many clinicians have refrained from using titanium curettes, prophy paste and ultrasonic devices because their effects on implant abutment surfaces were shown to be detrimental in vitro,4 and their long-term clinical effects on the peri-implant tissues were unknown.
More recent studies of electric toothbrushes with the natural dentition5–10 and laboratory models,11 however, found that these devices were more effective than manual brushes in removing interproximal plaque. In supervised clinical trials, second-generation powered mechanical brushes were found to be more effective in plaque removal overall than were manual brushes.12,13
We undertook a clinical study to compare the home-care effectiveness of a counter-rotational powered toothbrush with that of conventional manual home-care methods on indexes of periodontal health and implant survival at 24 months after uncovering of the implants.
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MATERIALS AND METHODS
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In 1991, the Dental Implant Clinical Research Group of the U.S. Department of Veterans Affairs, or DVA, in conjunction with the Core-Vent Corp. (now Paragon Implant Co.)—an implant company that provided funding and product for the study—undertook a six-year longitudinal study of the influence of dental implant design, application and site of placement on long-term clinical performance and crestal bone. Of 55 interested DVA Medical Centers, or DVAMCs, we selected 30 DVAMC implant research centers to participate; we also chose two independent dental schools. We selected these institutions after carefully screening them using the following criteria:
- – each implant team’s having adequate training and sufficient experience;
- – implant teams consisting of no fewer than two trained investigators;
- – separate investigators to conduct the study’s two phases (placing the implants and completing the follow-up evaluations);
- – willingness of all participants to undergo comprehensive training and technique standardization sessions before placing, restoring and maintaining implants.
Furthermore, investigators had to agree to undergo annual retraining and standardization testing. We trained and standardized the technique of 85 clinical investigators in the clinical protocols, application of the project’s evaluation criteria and data collection procedures.
The plaque index scores for the less accessible interproximal sites were lower for the powered brush than the scores for the more accessible vestibular sites cleaned by manual methods.
All potential patients had to have some type of dental implant and were carefully screened by the implant team before being included in the study. Each patient provided a comprehensive medical and dental history and underwent a dental evaluation. A comprehensive list of exclusion criteria has been published.14
The implants used in the study (Spectra-System, Paragon Implant Co.) were generally representative of the designs and materials that are available from all implant companies. The designs were a basket, a screw, a bullet and a grooved design; the materials were commercially pure titanium, titanium alloy and hydroxyapatite-coated titanium alloy. The implants were located throughout the mouth in various and randomly assigned configurations.14
We randomized each participating institution into one of four home-care groups:
- – Group 1 used only conventional manual methods for plaque removal;
- – Group 2 used manual methods plus twice-daily 0.12 percent chlorhexidine rinses (Peridex, Zila Pharmaceuticals Inc.) for the duration of the study;
- – Group 3 used a counter-rotational powered brush, or CRPB (Interplak Power Toothbrush, Conair Corp.);
- – Group 4 used the CRPB plus the same twice-daily chlorhexidine rinses as used by Group 2.
The use of a chlorhexidine rinse was assigned randomly to one-half of the hospitals in each of the CRPB and manual toothbrush groups.
The CRPB that we used was introduced in 1985. It has 10 spaced tufts of bristles that rotate 1.5 turns before reversing for another 1.5 turns. This reverse movement is intended to increase the scrubbing action and to force bristles into inter-proximal and subgingival areas. Adjacent tufts counter-rotate relative to each other, which has a stabilizing effect when the brush is placed on a given site. The bristle configuration is designed to reach between teeth and subgingivally.15–17 This design is different from other leading powered brushes, which use oscillating, vibrating or acoustic modes of action.
In the manual home-care group, the methods recommended for use by patients were customized according to patients’ needs and abilities, with each patient receiving optimal training. Additional training was provided as required at recall visits. The participating patients were asked to start using their manual hygiene regimen immediately after the uncovering procedure, continuing through the restorative phase and beyond. Each patient in this group received a soft manual toothbrush (TrueSoft, Lactona Co.); each also received either regular dental floss or specialized implant dental floss stocked by the various research sites and end-tuft brushes (End-Tuft, Lactona Co.) or interproximal brushes (Proxabrush, John O. Butler Co.).
Compliance with the home-care regimen was measured by observation of the physical manifestations of intraoral health. Both the CRPB and the manual groups used the dentifrices of their choice for the greater part of the study. (When the study began in 1991, the CRPB had a recommended companion dentifrice.) There was no recommended brushing duration in this study, as the model of CRPB used in this study did not have the two-minute timer now included with the product.
Patients were recalled at three, six, nine, 12, 18 and 24 months after the implants were uncovered, and yearly thereafter for a total of six years. Researchers measured four surfaces for each implant (mesial, facial, distal and lingual) after removing the prosthesis superstructure (except in maxillary single teeth, from which the crowns were not removed). Parameters examined for this report were levels of plaque, using the Silness and Löe Plaque Index,18 or PI; levels of gingivitis, using the Löe and Silness Gingival Index,18 or GI; levels of calculus, using a calculus index; clinical attachment levels (clinical probing depth and recession); and implant survival at the 24-month recall visit.
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RESULTS
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Of the 2,966 implants in the study, 1,409 were cleaned with the CRPB and 1,557 using manual methods.
We used the Wald statistic as the equivalent of the t-test for a multivariate situation. Values of P < .05 were accepted as statistically significant. For statistical analysis, we used the SPSS/PC+ statistical package (Version 5, SPSS Inc.) for the IBM PC.
Chlorhexidine rinse.
Regardless of whether chlorhexidine rinse was used, in each group, the CRPB was more effective than a manual brush plus interproximal aids, both in terms of clinical indexes and implant survival.
Plaque removal.
Figure 1
provides the mean PI values for all sites. The treatment effect appeared to peak around the nine-month interval but was sustained through 24 months at a statistically significant level (P < .001 Wald statistic). At all recall intervals, 66 to 72 percent of all implant surfaces cleaned by the CRPB were free of plaque (PI score of 0), compared with 50 to 58 percent of all implant surfaces cleaned by manual methods. It is interesting to note that at each interval, the PI scores for the less accessible interproximal sites were lower for the powered brush than the scores for the more accessible vestibular (buccal and lingual) sites cleaned by manual methods.
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Figure 1. Mean scores on the Silness and Löe18 Plaque Index of all sites pooled. At each visit, the counter-rotational powered toothbrush, or CRPB, was found to have removed more plaque than the manual toothbrush.
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Gingivitis.
Similar to the results for the PI, the CRPB group had significantly less gingival inflammation than the manual methods group (P < .001 at 18 months and P < .01 at 24 months Wald statistic). Figure 2 shows the mean GI values for all sites.
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Figure 2. Mean scores on the Löe and Silness Gingival Index18 for all sites pooled. At each visit, the group that had used the counter-rotational powered toothbrush, or CRPB, was found to have better gingival health than the group that had used manual toothbrushes.
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Calculus.
Both groups had low calculus values (< 10 percent with a score of 1), and there were no statistical differences between groups.
Attachment levels.
For the purposes of this study, we defined attachment level as recession plus probing depth. To facilitate measurement, the detachable prosthetic superstructure was removed. A repeated-measures analysis with a banded covariance structure across visits yielded similar results for the two groups. The CRPB group exhibited a progressive gain in attachment levels over 24 months, while the tendency in the manual group was to lose attachment (Figure 3). The CRPB group tended toward decreasing recession, while the manual group remained fairly constant in this regard. However, the manual group demonstrated slowly increasing probing depths. When we analyzed the implants in the partially edentulous patients, we adjusted the attachment levels for the control tooth readings (Figure 4) in an attempt to reduce measurement "noise" by eliminating correlations within the same patient because of systemic changes and because of measurement technique variations among clinicians. This caused the interaction terms to become insignificant, revealing a significant difference between treatments (P = .002) and significant differences over time (P = .004). During the 24-month period evaluated, the CRPB group experienced coronal migration of clinical attachment levels at all sites of approximately 0.6 millimeters, vs. the manual group’s values of 0.4 mm, when adjusted for control teeth (Figure 4). Again, the CRPB group’s interproximal values were superior to those of the manual-brush-plus-aids group.
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Figure 3. Attachment levels of all sites pooled. The attachment levels for all implants in the group that had used the counter-rotational powered toothbrush, or CRPB, were significantly better than those for implants in the group that had used manual toothbrushes (P < .05, 95 percent confidence interval, or CI).
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Figure 4. Adjusted attachment levels of all aspects combined. The attachment levels for implants in partially edentulous patients in the group that had used the counter-rotational powered toothbrush, or CRPB, were significantly better than those for implants in similar patients in the group that had used manual toothbrushes (P < .05, 95 percent confidence interval, or CI).
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Implant survival.
During the first 24 months of the study, 142 implants (89 in the manual group, 53 in the CRPB group) failed after being uncovered, for a variety of reasons. This corresponds to a 5.9 percent overall loss in the manual group and a 3.9 percent overall loss in the CRPB group (Table).
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DISCUSSION
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In this study, we found the CRPB to be a safe and effective oral hygiene aid for patients with endosseous implants. Such patients face special hygiene challenges. Most long-term prospective studies, like this one, indicate that people with dental implants can achieve continued oral health.19 However, numerous reports in the literature describe cases in which at least one implant steadily loses both bony and connective tissue support. Explanations for this phenomenon typically revolve around considerations of either peri-implantitis from a bacterial origin or loss of integration through occlusal overload. Diagnosis of occlusal overload may be difficult to achieve in every case; sometimes it is almost one of exclusion when peri-implant radiolucency occurs without any coronal breakdown of peri-implant tissues. The occurrence of peri-implantitis of bacterial origin is an increasingly documented phenomenon and may prove a frequent cause of implant failure. The CRPB may help combat peri-implantitis.
The long-term use of a chlorhexidine rinse in this study did not have a significant effect on periodontal parameters. This may be consistent with the results of Ong and colleagues,20 who sampled 37 implant sites in 19 patients with commercially pure titanium fixtures.
Apse and colleagues21 postulated that the gingival sulcus around natural teeth may function as a bacterial reservoir to colonize implant sites: "The longitudinal success of osseointegration in edentulous patients may be due, in part, to a reduced intraoral challenge by implicated periodontal pathogens and, conversely, the presence of such pathogens in partially edentulous patients may conceivably hasten subsequent peri-implant disease if patients are not well-maintained."
Over a long period, seemingly small improvements in plaque and gingivitis levels may translate into a demonstrable gain in clinical attachment levels.
Even though implants have greater interproximal spacing than the natural dentition and therefore should have enhanced access for oral hygiene, Quirynen and colleagues22 reported that in 86 patients with two overdenture fixtures per patient, only 40 percent of the approximal surfaces were without plaque and only 55 percent were without inflammation. While frequent professional recalls for supportive therapy may be able to overcome some or most of these deficiencies,23 home care is critical.
In the natural dentition, the CRPB has been shown to be superior to a manual brush in plaque removal and gingivitis reduction.8,9 It has reduced interproximal plaque and gingivitis better than either a manual brush used alone4 or manual brush used in combination with interproximal aids such as dental floss.10 It has been demonstrated to be effective in patients with periodontitis,8 patients needing periodontal maintenance,16 geriatric patients24 and orthodontic patients.25
The peaking of the treatment effect for plaque and gingivitis indexes in this study by six to nine months is similar to that described by Quirynen and colleagues8 in their study of the same CRPB in a population with moderate periodontitis. It appears as though a "maximal clinical reduction" in gingival inflammation occurs near this time frame. The improvement is also comparable with that reported by Yukna and Shaklee.10 In their unsupervised clinical evaluation of a CRPB used on the natural dentition, Yukna and Shaklee observed a general 50 percent improvement from baseline in clinical conditions, compared with a 20 to 25 percent improvement associated with manual oral hygiene methods.10 As in their study, our study involved unsupervised use of the CRPB, and technique was reinforced only at recall appointments, a regimen that most closely models the reality of clinical practice.
The clinical significance of what appear to be small changes in plaque and gingivitis levels is always in question.26,27 The result of a 0.4- to 0.6-mm difference in clinical attachment level at 24 months may be clinically significant and is comparable to that in a recent report in the literature.28 Over a long period, however, seemingly small improvements in plaque and gingivitis levels may translate into a demonstrable gain in clinical attachment levels. Given what is known about the nature of the soft-tissue interface with titanium abutments,29 however, this gain most likely reflects a decrease in probe penetration that correlates with a reduction in gingival inflammation.30 Additionally, at the 24-month point in this study, the manual methods group had lost more implants than the CRPB group. This difference is significant and certainly meaningful. The loss of an implant is the most definitive result assessable in this population, and its clinical implications cannot be disputed.
The superior cleaning, maintenance of gingival health and attachment level improvement demonstrated by the CRPB in our study indicates that it is a home-care device well-suited to dental implant maintenance. It is not traumatic to implants and promotes better oral health than manual methods. Interproximally, its performance is superior to that of the manual toothbrush used with dental floss and interproximal brushes—the current regimen suggested by most periodontists.
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CONCLUSION
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Before this study was conducted, the effects of a powered toothbrush on the tissues that surround an endosseous implant, in terms of safety and efficacy, were unknown. Our study has shown that in patients with implants, the CRPB is safe and more effective than a manual brush used with interproximal aids. Its effectiveness may be the result of its brushhead, which can reach around the prostheses associated with implants and clean the abutment/soft-tissue interface. Additionally, after 24 months, implants brushed with the CRPB had a significantly better survival rate than those brushed with manual methods. These outcomes need to be further validated by other independent clinical studies.
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FOOTNOTES
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This investigation was funded by the Dr. Gerald Niznick Research Foundation, Procter & Gamble, Bausch & Lomb and Conair Corp.
The opinions or assertions expressed or implied are strictly those of the authors; they are not to be construed as official and do not necessarily reflect the opinions or policies of the U.S. Department of Veterans Affairs.
The authors thank all of the professional participants at the 30 Department of Veterans Affairs Medical Centers and the two dental schools for taking part in this study.
A complete statistical analysis is available from the authors.
Dr. Truhlar is a clinical investigator, Northport Department of Veterans Affairs Medical Center, Northport, N.Y.
Dr. Morris is the director, Dental Clinical Research Center, and the project director, Dental Implant Clinical Research Group, Department of Veterans Affairs Medical Center, Dental Research (154), 2215 Fuller Road, Ann Arbor, Mich. 48105. Address reprint requests to Dr. Morris.
Dr. Ochi is the assistant director, Dental Clinical Research Center, and assistant project director, Dental Implant Clinical Research Group, Department of Veterans Affairs Medical Center, Ann Arbor, Mich.
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ABSTRACT
MATERIALS AND METHODS
