JADA Continuing Education
The effect of periodontal surgery on bite force, occlusal contact area and bite pressure
Arzu Alkan, DDS, PhD,
Ilker Keskiner, DDS,
Selim Arici, DDS, MmedSci, PhD and
Shuichi Sato, DDS, PhD
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ABSTRACT
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Background. Tooth mobility resulting from the loss of periodontal support or trauma induced by periodontal surgery may change the amount of bite force (BF) and bite pressure (BP) and number of occlusal contact areas (OCAs). The aim of the authors’ study was to compare BF, BP and OCA of teeth with periodontal disease before and after periodontal surgery with similar values of healthy teeth.
Methods. The authors performed quantitative analysis of BF, BP and OCA using a pressure measurement film. Ten patients with periodontitis who needed periodontal surgery served as the test group. The authors took measurements of BF, BP, OCA and mobility (using Miller’s Mobility Index) just before surgery and at one, four and 12 weeks after surgery. They also measured clinical attachment levels (CAL) before surgery and 12 weeks after surgery. Ten subjects without periodontitis served as the control group.
Results. Although BF and OCA increased the first week after periodontal surgery, analysis of variance (ANOVA) showed no statistically significant differences at a 95 percent confidence interval. There were statistically significant differences between first-week mobility and that at four and 12 weeks (P = .001). A factorial ANOVA showed significant interaction between BF and mobility (P < .05).
Conclusions. The authors’ findings suggest that changes in BF, BP and OCA were not affected by periodontal surgery. However, mean mobility values and BF are correlated. Further investigations of this measurement method involving larger study populations and a longer follow-up period are needed.
Clinical Implications. It seems to be helpful to follow occlusal changes after periodontal surgery using a pressure measurement film. It also may be suggested that this measurement method could be used to evaluate the treatment prognosis.
Key Words: Pressure measurement film; bite force; occlusal contact area; bite pressure; periodontal surgery; tooth mobility
Periodontal health, surface area of attachment apparatus and clinical crown height are some of the local factors that influence occlusal forces acting on the dentition. Musculoskeletal factors, the temporomandibular joint (TMJ), tooth mobility and the type of the measuring device are other factors the clinician must take into consideration when determining the distribution of occlusal forces on the dental arch. Even the slightest mobility of the first tooth to contact may result in depression of the tooth, which causes other teeth to contact, and thus occlusal contact points and occlusal contact areas (OCAs) change. There are studies in which the effects of mobility on the results of surgical and nonsurgical periodontal therapy have been evaluated.1–5 However, it may be interesting to investigate whether periodontal surgery–induced tooth mobility could alter biting abilities during the healing period.
There still is not a precise quantitative method of measuring tooth mobility; however, movement of teeth due to the loss of periodontal support and periodontal surgical trauma may change the number of OCAs, as well as the amount of bite force (BF) and bite pressure (BP). A pressure-sensitive measurement film and occlusal evaluation system (Dental Prescale, FujiFilm, Tokyo) was developed in the last two decades to analyze these variables quantitatively.
We conducted a study to evaluate the changes in BF, BP and OCA values of teeth with periodontal disease before and after periodontal flap surgery using graft materials and guided tissue regeneration procedures. We compared these changes with changes in teeth that had healthy periodontia.
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SUBJECTS, METHODS AND MATERIALS
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The study group consisted of 10 patients (five male, five female) with periodontitis who underwent periodontal surgery after initial periodontal therapy (scaling, root planing and delivery of oral hygiene instructions). The mean age of the patients was 35.7 years (range 21–47 years). The control group consisted of 10 volunteers with healthy periodontia (five male, five female). The mean age of the control group was 32.8 years (range 22–43 years). All of the participants had complete dentition except for the third molars. In addition, none of them had prostheses or restorations in the mouth. None of them complained of any symptoms of masticatory disharmony or TMJ disorders, and none had any malocclusion.
Periodontal examination.
We evaluated the teeth’s clinical attachment levels (CAL) and mobility in the test subjects. Using a Williams’ periodontal probe, we measured CAL as the distance between the cementoenamel junction and the base of the periodontal pocket before surgery and at 12 weeks. The mobility measurements were taken before surgery and one, four and 12 weeks after surgery, according to the Miller’s Mobility Index.6 The periodontal examination was done by the same examiner.
Measurement of BF, BP and OCA.
We measured BF, BP and OCA by means of a pressure measurement film (Dental Prescale 50H , Type R, FujiFilm, Tokyo) and an image scanner (Occluzer, FujiFilm). This pressure-sensitive film contains microcapsules of color-forming materials that form red spots when the film is bitten (Figure 1
). Color of different density and intensity forms according to the magnitude of the pressure applied. The clinician calculates BF, BP and OCA after the sheet is scanned and subjected to analysis by an occlusion pressuregraph. The calculation takes into consideration the area and different densities of color (Figure 2). We took our preoperative measurements with Dental Prescale just before surgery. The subjects were seated with their heads upright and in an unsupported natural head position. After several practice attempts to maintain intercuspal bite, we placed the sheet carefully in each patient’s mouth so that the midline of the arch coincided with the midline of the sheet. We took care to include all the teeth in the mouth. We discarded the buccal mucosa areas of the sheet so as not to deform it. We instructed each patient to bite as forcefully as possible for about three seconds.
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Figure 1. Pressure measurement film (Dental Prescale, FujiFilm, Tokyo). Image reproduced with permission of FujiFilm.
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Figure 2. Example of the form of analysis of bite force (BF), bite pressure (BP) and occlusal contact area (OCA). BF (newtons [N]): Pressure multiplied by the area. OCA (square millimeters): Total area of the impressed marks on the sheet. BP (megapascals [MPa]): The BF per 1 mm2 of the OCA.
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Periodontal operation.
We used the modified Widman flap technique, without vertical incisions, in all of the test group patients. After flap reflection, we removed the granulated tissue and planed roots. We did not perform bone-resective procedures. Two- or three-walled infrabony defects were treated by the graft material and membrane. Every patient except one had one infrabony defect that we treated by means of a graft material and a membrane. Only one patient received graft material and membrane in two different infrabony defects; we used Bioactive glass (Unigraft, Unicare Biomedical, Laguna Hills, Calif.) and a resorbable membrane (Atrisorb, Atrix Laboratories, Fort Collins, Colo.) for this purpose. We replaced the flaps and sutured them with interrupted sutures. We used no periodontal packing.
Statistical analysis.
We performed a factorial analysis of variance (ANOVA) to investigate the effects of the periodontal surgery on the BF, BP, OCA and mobility using the data taken from the study subjects at four time intervals and from the control group once at the beginning of the study. We used a paired Student t test to compare the attachment levels recorded for the subjects before the surgery and at 12 weeks after surgery. We applied all statistical analysis at the 95 percent confidence interval.
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RESULTS
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The table shows the mean changes in the BF, BP, OCA, number of occlusal contact points, tooth mobility and attachment level values representative for one-half of the jaw in intercuspal position—the region on which we operated.
The changes in mean BF and OCA values were almost parallel at the measurement intervals. At the first week after surgery, both the BF and OCA values were at their lowest, whereas the mean mobility value was at its highest (Figure 3, page 982). At four weeks, the mean mobility value had decreased, and BF and OCA values recovered almost to the preoperative measurement levels. Although there was an increase in the BF and OCA starting from postoperative week one until the end of the study period, ANOVA showed no statistically significant differences with the increase in time at a 95 percent confidence interval. However, we saw statistically significant differences in mobility (P = .001) at four and 12 weeks when compared with levels at week one. Mobility values of the control group (not shown in Figure 3) showed a statistically significant difference with only the first-week values of the test group. A factorial ANOVA showed significant interaction between the BF and mobility (P < .05). A decrease in the mean mobility value after the first postoperative week was accompanied by an increase in the mean BF value in the test group. The BF and OCA of control subjects always were greater than those of test subjects, but this difference was not statistically significant. We found a statistically significant difference (P = .034) between the preoperative and postoperative attachment levels at 12 weeks. However, statistical analysis showed no correlation between the attachment levels and the following parameters: tooth mobility, BF, OCA and BP.
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Figure 3. Changes in measured factors after test group’s periodontal surgery. A. Bite force. B. Occlusal contact area. C. Tooth mobility. Preop: Preoperative measurement.
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DISCUSSION
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The periodontology literature includes several studies regarding the effect of tooth mobility on surgical and nonsurgical periodontal treatment outcomes1–5; however, the effect of mobility on the BF, BP and OCA have not been examined extensively. BF and OCA have been measured with some pressure-sensitive devices throughout the years, but the results were controversial.7,8 The Dental Prescale system provides quantitative data on occlusal contacts and BF simultaneously on all occlusal points. Miyaura and colleagues9 investigated the effects of mobile teeth on masticatory function using Dental Prescale. The authors found that the presence of mobile teeth had no significant effect on the BF, BP and OCA. Also, Morita and colleagues,10 who used Dental Prescale, researched the relationship between periodontal condition and biting ability in a Chinese patient population. They found no correlation between periodontal status and biting ability.
To the best of our knowledge, there are no published studies evaluating how biting abilities are affected by the changes in tooth mobility after periodontal surgery.
Measuring BF, BP and OCA with Dental Prescale was a simple procedure, with the flexible film permitting natural occlusion. Other investigators have suggested that this characteristic makes it superior to other measurement systems.11,12 Dental Prescale is available in various types: S type, no wax; R type, wax on one face; and W type, wax on both faces. Although W type is able to detect the outline of the teeth and the location of occlusal contact points in the dental arch, we used R type because it was more sensitive to occlusal pressure. For this reason, we could not determine the occlusal contact points for individual teeth in the arch; neither could we compare Dental Prescale measurements of the teeth treated by the graft material and membrane combination with teeth treated by the flap procedure alone.
Occlusal contacts in the intercuspal position have significance for dental health. The evaluation of the area and force of occlusal contact is helpful for diagnosing a patient’s occlusal state. Riise13 found that a smaller number of occlusal contacts at light pressure than at hard pressure in the habitual position and concluded that the aim of occlusal adjustment should be to bring the number of occlusal contacts in light pressure to equal that in hard pressure. Kim and colleagues14 reported that the number of tooth contacts in the intercuspal position is significantly increased as clenching strength is increased. In our study, we found a significant correlation (P = .025) between the number of occlusal contacts and BF. On the other hand, the number of occlusal contacts decreased at the end of the study, but OCA increased. This may be explained by the union of small contact points to form one large contact point with the increase in BF. Also, new contact points might have appeared with the increase in BF. A broadened OCA would be beneficial in helping prevent excessive pressure on a tooth. This suggests that the diagnosis of the nature of occlusal contacts is important in control of occlusal force.
A number of factors might be responsible for the decrease in BF and OCA shortly after operation. The operation itself and inflammatory changes related to early healing may have caused the mobility of the teeth, thus resulting in the decrease in BF. Also, some patients might be reluctant to bite vigorously soon after surgery. The fear of feeling pain also could affect patients’ willingness to bite hard.
In contrast to the statistically significant decrease in the mobility values, the increase in the BF and OCA values at four and 12 weeks was not statistically significant. Majewski and Sponholz15 reported that the mobility recovers to the preoperative state after one month. In our study, the mobility value was even below the preoperative value at the first month. One possible reason for this insignificant difference may be the use of a subjective measurement system (Miller’s Mobility Index), since the naked eye cannot detect small changes in tooth mobility.
Periodontitis is a destructive disease, and the loss of the tooth-supporting tissues may cause tooth mobility. Although there was no significant difference in BF and OCA at any of the examination periods, BF and OCA tended to decrease at the first week after surgery and increase afterward. Also, patients with periodontitis tended to have less BF and OCA than did control subjects both preoperatively and postoperatively (P >. 05).
We took CAL measurements of the test subjects before surgery and at 12 weeks. We did not measure it at the first week and first month, since it would not be proper to probe the gingival sulcus and interfere with the early healing process. There was a significant difference between the preoperative and 12–weeks-postoperative attachment level values. This might have affected the decrease in the mobility. Contrary to our expectations, attachment levels showed no significant correlation with any of the measured parameters.
We observed that at the end of our study, the BP decreased below the preoperative values. In other words, the increase rate of OCA (16 percent) was more than that of BF (8 percent), resulting in decreased BP.
This study suggests that changes in BF, BP and OCA were not affected by periodontal surgery. In other words, changes in tooth mobility during healing did not affect biting abilities. Miyaura and colleagues,9 in an epidemiologic study, also failed to find any differences in biting abilities between mobile and nonmobile teeth. The author stated that the number of teeth was the most influential factor on masticatory function; therefore, it seems as if preservation of periodontally involved teeth by either surgical or non-surgical periodontal therapy should be the goal for good masticatory function.
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CONCLUSION
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Although further investigations with larger study populations and longer follow-up periods using this measurement method are needed, use of a pressure measurement film seems to be helpful in direct and objective observation of the occlusal changes that occur after periodontal surgery. It also may be suggested that this measurement method could be used for evaluation of the projected treatment outcome. Although we cannot state this definitively at this stage and with this study population, monitoring via use of pressure measurement film also may be used to predict the future prognosis of a periodontal problem.
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FOOTNOTES
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Dr. Alkan is an assistant professor, Department of Periodontology, Ondokuz Mayis University, Faculty of Dentistry, 55139 Kurupelit, Samsun, Turkey, e-mail "arzualk{at}omu.edu.tr". Address reprint requests to Dr. Alkan.
Dr. Keskiner is a research assistant, Department of Periodontology, Ondokuz Mayis University, Faculty of Dentistry, Samsun, Turkey.
Dr. Arici is an associate professor, Department of Orthodontics, Ondokuz Mayis University, Faculty of Dentistry, Samsun, Turkey.
Dr. Sato is a lecturer, Department of Oral and Maxillofacial Surgery, Tohoku University School of Dentistry, Sendai, Japan.
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REFERENCES
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ABSTRACT
SUBJECTS, METHODS AND MATERIALS
