A two-month study of the effects of oral irrigation

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1 A two-month study of the effects of oral irrigation and automatic toothbrush use in an adult orthodontic population with fixed appliances James G. Burch, DDS, MS, Richard Lanese, PhD,b and Peter Ngan, DMDc Columbus, Ohio Forty-seven adult orthodontic patients with fixed orthodontic appliances were divided into three study groups: (1) oral irrigation with automatic toothbrush, (n = 16); (2) oral irrigation with manual toothbrushing, (n = 16); (3) control group with continued normal toothbrushing only, (n = 15). Gingival and plaque indices, bleeding after probing, and gingival sulcus depths were assessed at baseline, 1-month, and 2-month periods. Marked and significant gingival and plaque improvements from baseline were measured in all three study groups. After 1 to 2 months use of the automatic toothbrush and/or the oral irrigation device, there was a significant reduction in plaque when compared with the control group who used only the manual toothbrush (p = 0.026). Also, there was a significant reduction in gingival inflammation (p = 0.045) and evidence for reduced bleeding after probing (p = 0.037). No significant differences were found in probe depths among the three study groups, however, use of both devices reduced the pocket depth significantly from baseline by 0.5 mm (p < ). For this population of orthodontic patients, significant reductions in plaque, gingival inflammation, and a tendency for reduced bleeding after probing occurred in both groups with the power device. These improvements were most attributable to the effect of the oral irrigation device. (AM J ORTHOD DENTOFAC ORTHOP 1994;106:121-6.) Fixed orthodontic appliances impair plaque removal, oral hygiene, and gingival health. Plaque is harbored by the appliances, and hinders its removal. Gingivitis develops and can become quite profound in 21 days.' The gingivitis can be reversed in 5 days by thorough plaque removal. 2 Because of interferences in plaque removal by the fixed orthodontic appliances, adjunctive aids and plaque removal devices become helpful in regaining or maintaining gingival health. Water irrigation devices and automatic toothbrushes have been considered beneficial adjuncts to normal manual toothbrushing and plaque removal. Removal of some plaque from specific surfaces of various teeth can be achieved with a normal manual toothbrush.':" The use of power toothbrushes by orthodontic patients has also been reported. A few of these publications report significant benefits. However, other investigators report no differences between the use of a power brush and a manual toothbrush. Various features of automatic toothbrushes have been tested and Fromthe Ohio State University. 'Professor, Department of Orthodontics, College of Dentistry. 'Professor, Department of Preventive Medicine, College of Medicine. 'Associate Professor, Department of Orthodontics, College of Dentistry. Copyright 1994 by the American Association of Orthodontists /94/$ /1/43788 reported, as well. Brush head design reportedly is a useful feature, especially in proximal areas.p:" However, a patient with normal dexterity and reasonable sensitivity tolerance can achieve good plaque removal and maintain good gingival health no matter what method is used."!" Oral irrigation devices with a pulsating stream of water directed through a tip orifice to specific tooth surfaces have been shown to clean teeth and appliances of bacteria and debris, They also help retard accumulation of plaque and calculus, thus reducing gingival inflammation. Water irrigation causes minimal trauma to diseased soft tissues, but reportedly does not induce bacteremia when used according to the manufacturer's instructions in patients with gingivitis The intent of this study was to determine the benefits of 2 months use of adjunctive oral irrigation and automatic toothbrushing in an adult orthodontic population with fixed appliances in place for at least 1 month in the presence of generalized gingivitis. MATERIALS AND METHODS Forty-seven orthodontic patients, between the ages of 21 and 48 years, being treated in an orthodontic clinic in a large midwestern university were recruited as subjects in this study. Patients were accepted who had full fixed orthodontic appliances in place. Eight teeth were selected for continued as- 121

2 122 Burch, Lanese, and Ngan American Journal oforthodontics and Dentofacial Orthopedics August 1994 sessment: two maxillary and two mandibular molars, one maxillary second premolar, one mandibular second premolar, one maxillary incisor, and one mandibularincisor. The patient must have had fixed appliances in place for a minimum of I month and a diagnosis of generalized gingivitis. The medical history was reviewed to exclude anyone with a history of heart murmur, rheumatic heart disease, rheumatic fever, mitral valve prolapse, cardiovascular problems, or history of any condition that might put them at risk if a bacteremia were to occur. Patients were excluded if they were pregnant or planning a pregnancy within the next 3 months, or if they were taking antibiotics. Subjects were discontinued if they became pregnant (as determined by menstrual history) or if they began antibiotic therapy during this investigational period. Informed consent was obtained, and patients were randomly assigned to either treatment and control groups, stratifying by sex. One group of 15 subjects served as the control group. They were instructed to continue cleaning their teeth and orthodontic appliances in their usual manner of manual toothbrushing. A second group of 16 subjects was instructed to use an adjunctive oral irrigation device (WaterPik, Teledyne WaterPik, Ft. Collins, Colo.) with tap water once per day in addition to using their usual manual toothbrush. This oral irrigation device produced a pulsating stream of water with an exit pressure of 55 to 65 psi, using 400 to 500 ml tap water for each irrigation. A third group of 16 subjects was instructed to use the adjunctive oral irrigation device and an automatic toothbrush (Plaque Control 2000 by Teledyne WaterPik), once daily with regular toothbrush. The automatic toothbrush delivered an elliptical motion similar to the Bass sulcular technique of manual brushing:' To calculate the proper sample size, we estimated the control mean for probe depth at the end of 2 months to be 2 mm, with a standard deviation, SD = The mean for the automatic toothbrush and oral irrigation group was 1.5 and for the oral irrigation and manual toothbrush group was 1.75 with a SD = 0.45 for both groups. With the charts from Netter and Wasserman." the sample size was calculated at approximately 15 per group with a power of 0.80 and ex at As for compliance, each subject noted on an assigned calendar the time of day of the use of the device. Any other anecdotal information was also noted on the calendar. Four parameters were measured and recorded for the eight test teeth of each subject of all groups. Plaque was assessed by the Silness and Loe plaque index" in which 0 = no plaque in the gingival area; 1 = a film of plaque adhering to the free gingival margin and adjacent area of the tooth. The plaque may be recognized only by running a probe across the tooth surface; 2 = moderate accumulation of soft deposits within the gingival pocket and on the gingival margin and! or adjacent tooth surface, which can be seen by the naked eye; and 3 = abundance of soft matter within the gingival pocket and! or on the gingival margin and adjacent tooth surface. Tooth surfaces scored were (1) distofacial, (2) facial, (3) mesiofacial, and (4) entire lingual gingival marginal surfaces. Patient indices were calculated by averaging means for each individual tooth. Gingival inflammation (GI) was assessed by the Loe and Silness index." in which 0 = normal gingiva; 1 = mild inflammation, slight change in color, slight edema; no bleeding on palpation; 2 = moderate inflammation, redness, edema, and glazing; bleeding on palpation; and 3 = severe inflammation, marked redness and edema, ulcerations, tendency to spontaneous bleeding. Standard clinical probing was accomplished for the same four surfaces of the eight teeth. Probe depths were measured with a standard UNC no. 15 periodontal probe and recorded to the nearest millimeter demarcation. Bleeding assessment of the four sites per tooth were made after probing and varied from the method described by Muhlemann et al." Thirty seconds after probing, the tooth surface areas were observed to determine the presence of bleeding. Any tooth surface area presenting bleeding after the previous GI index scoring was recorded as a positive reading, as well as those surfaces presenting a point of bleeding because of probe depth measurement. This determination was considered as a bleeding after probing (BAP) assessment. Bleeding was expressed as number of bleeding points appearing after GI index scoring and probing of sulcus depth. Three investigators were trained in assessing all four parameters. Evaluators were blind to the group designation of the individual patients. INTERRATER RELIABILITY A mixed design analysis of variance was used to estimate the reliability of the three raters in their assessments of 12 volunteers. This analysis was repeated for each of the four measurements: plaque index, gingival index, probe depth, and BAP. The reliability coefficients obtained by these analyses were based on partitioning the variance between and within subjects and further separatingthe within subjects component into judge differences and residual error as described by Winer." The coefficients obtained for the plaque index, gingival index, sulcus depth index, and the bleeding after probing index were 0.98,0.96,0.62, and 0.97, respectively. STATISTICAL METHODS Means and standard errors were calculated for the three groups at baseline, 1 month, and 2 months for each of the four outcome measures. Each outcome was analyzed separately with a 3 by 2 mixed design analysis of covariance (study group by time). Means at I and 2 months after baseline for the two study groups and control group were adjusted for baseline values. Difference between the two oral irrigation groups and controls were compared with Dunnett's t test. Whether significant differences were found between each of the oral irrigation groups and the controls, the oral irrigation groups were combined and compared with the controls."

3 American Journal of Orthodontics and Dentofacial Orthopedics Volume 106, No.2 Burch, Lanese, and Ngan 123 Table I. Difference from baseline for four outcome measures by treatment group and time of follow-up: Mean differences, standard errors, and p levels* Automatic brushing plus Oral irrigation plus manual Manual brushing irrigation (n = 16) brushing (n = 16) only (n = 15) Outcome measure x I SE I p x I SE I p x I SE I p Plaque index, I month Plaque index, 2 months Gingival index, I month Gingival index, 2 months Pocket depth (mm) I month Pocket depth (mm) 2 months Bleeding after probing in dex, I month Bleeding after probing in dex, 2 months OF ratio probabilities from one-way repeated measures ANOYA. Table II. Adjusted means and standard errors of four outcome measures for three groups of patients by treatment group and time of follow-up Baseline One-month Two-month measure follow-up' fallow-up' Plaque index Automatic brushing + oral irrigation (n = 16) 0.90 (0.12) 0.43 (0.10) 0.43 (0.08) Oral irrigation + manual brushing (n = 16) 0.88 (0.12) 0.50 (0.07) 0.39 (0.07) Manual brushing only (n = 15) 0.92 (0.12) 0.84 (0.15) 0.53 (0.10) Gingival index Automatic brushing + oral irrigation 1.22 (0.08) 0.95 (0.07) 0.76 (0.08) Oral irrigation + manual brushing 1.16 (0.05) 0.88 (0.09) 0.82 (0.06) Manual brushing only 1.13 (0.07) 1.02 (0.09) 0.99 (0.08) Pocket depth (mm) Automatic brushing + oral irrigation 2.31 (1.3) 1.92 (0.14) 1.73 (0.10) Oral irrigation + manual brushing 1.99 (0.12) 1.81 (0.12) 1.93 (0.08) Manual brushing only 2.16 (0.11) 1.92 (0.12) 1.93 (0.09) Bleeding index Automatic brushing + oral irrigation 0.47 (0.06) 0.24 (0.05) 0.11 (0.03) Oral irrigation + manual brushing 0.35 (0.04) 0.25 (0.05) 0.15 (0.02) Manual brushing only 0.40 (0.07) 0.31 (0.06) 0.23 (0.05) djusted by analysis of covariance for differences in baseline measurements. RESULTS Means and their standard errors at baseline, at the I-month, and 2-month follow-up examinations are presented in Tables I to III for each of the three study groups, Changes that occurred over the 2-month study period reflect marked and significant improvements in all four outcome categories for the two experimental groups and the control group. Statistical analyses of the differences among the three study groups indicated an experimental effect due primarily to the use of an oral irrigation device on three of the four outcome measures, For the plaque index, there were significant differences between groups and between the I-month and 2-month observation periods after adjusting for differences in baseline scores. Although the interaction of group and time did not reach significance (p = 0.106), there is the suggestion that the pattern of change from the first to the second follow-up examination for the three groups of subjects may not be the same. Most of the change between the first month and the second month occurred in the manual brushing with oral irrigation group. An examination of the means of the two oral

4 124 Burch, Lanese, and Ngan American Journal of Orthodontics and Dentofacial Orthopedics August 1994 Table III. Summary of repeated measures analysis of covariance of group* and timet effects for four outcome measures F ratio: Group F ratio: Time F ratio: Group x time Outcome measure df F I p df F p df F p Plaque index 2, ,42 Gingival index I Pocket depth (mm) I Bleeding after probing I , *Treatment: Auto brushing and oral irrigation versus oral irrigation and manual brushing versus manual brushing only. tone-month versus 2-month follow-up. irrigation groups suggests that they are equally successful in reducing plaque and more successful than the manual brushing group. However, we were unable to confirm this by Dunnett's t test, probably because the two experimental groups had similar mean responses. When these two groups were combined, however, this comparisonyielded means of 0.44for the patients using the oral irrigation device and 0.68 for the patients serving as controls (t = 2.85, P = 0.007). Analysis of covariance of gingival inflammation indicated the three groups responded differently to the prescribed regimens (p = 0.045). There was no significant difference between the 1- and 2-month responses to treatment and no evidence of a group by time interaction. Again, patients who used the oral irrigation device showed a greater reduction in gingival inflammation than did the manual brushing control group. The comparison between the combined experimental groups and the control group yielded means of 0.85 and 1.01, respectively (t = 2.61, P = 0.012). Probe depth was not substantially reduced by the experimental procedures, nor was there a significant change between the l-rnonth and 2-month follow-up periods. The pattern of change between the two followup examinations was approximately the same for the three groups. When the two experimental groups were combined and compared with the control group, means were 1.85 and 1.93, respectively, a trivial difference (r = 1.07, P = 0.291). However, inspection of the changes in group means (Table II) shows the greatest improvements in pocket depth is achieved in the irrigation and power brush group after 2 months. The 0.5 mm improvement measured is approximately twice that of the other two groups. The three group means for BAP were not significantly different from each other in the mixed design analysis of covariance, at each examination. However, there appeared to be fewer points of bleeding after use of the oral irrigation device (p < , , and 0.01). The overall difference between l-month and 2 month means was highly significant (P < ) with fewer bleeding points at 2 months for all groups. When we combined the two groups that were using the oral irrigation device and compared them with the manual brushing group, their respective means of 0.19 and 0.27 were significantly different (t = 2.15, p = 0.037). Patients who used the oral irrigation device had fewer bleeding points after probing both at 1 month and 2 months. Again, inspection of the changes in group means (Table I) shows the most reduction in bleeding for the irrigation and power brush after 2 months (p < ). DISCUSSION Significant reductions in gingival inflammation and plaque were found in the control group, as well as in both treatment groups. Improvements found in patients in the control group are not surprising and may be attributed to the well-known Hawthorne Effect," where improvement is often measured in a group's usual performance when enlisted in a study and under observation. During 2 months of use of the automatic toothbrush and / or the oral irrigation devices there was significantly greater reduction of plaque and gingival inflammation in both treatment (device) groups than in the control group that used only the normal manual toothbrush. There was a trend toward reduced numbers of BAP points. Probing depths did not decrease nor differ among treatment and control groups. Although the numberof patients participatingin this study was relatively small, highly significant changes from baseline were observed in all three groups. However, the magnitude of differences among the three groups on each of the outcome measures were small. Nevertheless, these differences created an expected pattern. The largest reductions in plaque, inflammation, and

5 American Journal of Orthodontics and Dentofacial Orthopedics Volume 106, No.2 Burch, Lanese, and Ngan 125 bleeding occurred within the first month of investigation. Further reductions between the I-month followupand the 2-month follow-up were relatively small but were at significant or nearly significant levels. This suggests that benefits from using the oral irrigation device may be experienced early, perhaps in the first week or two of treatment, and continue beyond the period of observation of this study. Although we measured no statistical differences in probe depths among the three groups over the study period, it should be noted that our preliminary reliability study indicated the measurement error was greatest for probing. Assuming that this measurement error was nondifferential, its effect would favor the null hypothesis. On the other hand, highly significant changes were observed from baseline by all three groups. Furthermore, detectable probe depth reduction (gingival sulcus depth shrinkage) may necessitate more time than 2 months. If maintenance or further decrease in plaque and gingival scores occurred with time after the 2 monthevaluation point, gingival shrinkage might occur and probe depth reduction be more evident. To further reduceprobe measurement error it is recommended that future studies refine the technique of measuring pocket depth, include practice with feedback, and compare resultsamong raters before engaging in the experiment itself. Our assessment of BAP appeared to be higher for gingivitis patients as compared with bleeding on probing (BOP) standards for gingivitis patients as described by Muhlemann et al. 45 The BAP scores as determined in this study were derived by combining BOP points with GI bleeding points. Therefore BAP scores were expected to be greater than BOP scores. The data confirmed this assumption. A recent study by Jackson" reported that there was no statistically significant benefit to the orthodontic patient from using an electric toothbrush, a water irrigation device, or a combination of the two. In contrast, the present study shows that daily water irrigation, with manual or electric brushing, provided significant improvement in gingival inflammation and bleeding after 2 months. The benefits of the automatic toothbrush were not as convincing and must be studied further. More detail may become evident in further analysis of interproximal versus flat surface conditions. Analysis of the condition around banded versus bonded molars is being accomplished and may reveal more specific conclusions. This study included more patients in each group than the Jackson study." This fact may partially explain the statistical differences between the studies. All patients in this study were adults, possessing a chance for less variability in use and compliance. There was also a difference in action of the power brushes used in the two separate studies. The action of the head of the automatic toothbrush used in this study may be more effective in removing plaque from around orthodontic wires, brackets, bands, and auxiliary attachments, than the power brush tested by Jackson." The difference attributable to the oral irrigation device or automatic toothbrush may not be a function of superiority over the manual toothbrush. Patients may be attracted to the novelty of the power devices and clean their teeth with greater intensity and thoroughness for a longer period of time than if they would when assigned to the manual brushing only. An improved study design would prescribe a precise procedure, length of time and frequency for manual brushing, automatic brushing, and oral irrigation. Such instruction to patients would make the study more repeatable by others and allow comparisons to be made between alternative methods of using these devices. In any case, the oral irrigation device and automatic toothbrush may in themselves motivate patients to improve their oral health. One-month results of this study have been reported previously." In conclusion, this current 2-month study not only shows differences in the four parameters between baseline and the 2-month follow-up but shows changes that occurred during the second month of the investigation. This study indicates that during the second month of use, the oral irrigation device, in combination with either the manual or automated toothbrush, was of significant value in reducing plaque, gingival inflammation, and bleeding. The short duration of this study may have limited the findings regarding pocket depth. However, the group that used daily irrigation and the power toothbrush experienced the greatest reduction of pocket depth after the 2-month period (0.5 mm) for this patient population of adults with fixed orthodontic appliances. 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