Journal of
Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 218--225
Influence of different narrative instructions to record the occlusal contact with silicone registration materials R. OBARA*, O. KOMIYAMA†, T. IIDA†, T. ASANO†, A. DE LAAT‡ & M . K A W A R A † *Nihon University Graduate School of Dentistry at Matsudo, Matsudo, †Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, Matsudo, Japan and ‡Department of Oral Health Sciences, Catholic University of Leuven, Leuven, Belgium
SUMMARY This study examined the influence of narrative instructions on the occlusal contact area, occlusal contact point and masticatory muscle activities in normal subjects. Twelve healthy men and 12 healthy women with no more than one missing tooth per quadrant participated. Surface EMG was recorded from the masseter and temporal muscle. As a control measurement, intercuspal position was maintained to produce a habitual clenching record (NCR) while the occlusal contact area and occlusal contact point was recorded by means of silicone material. Subsequently, the occlusal contact area was recorded with the narrative instruction for minimum clenching record (MCR), light clenching record (LCR) and strong clenching record (HCR). While the EMG activity (%MVC) increased modestly from MCR to LCR (from 93 20% to 115 15%), the occlusal contact area increased rapidly (from 172 113 mm2 to 268 156 mm2)
Introduction To diagnose occlusal-related disorders (1–3), occlusal tooth contacts have been recorded in a variety of groups with occlusal articulating paper (4, 5), occlusal strips or silk (6), black silicone material (7) and the pressure sensor sheet (8–10). As the nature of occlusal contacts is affected by biting pressure, some devices were developed to quantify the contact area together with bite force (11, 12) or by recording elevator muscle electromyography (EMG) (13). Considering the various clinical opinions and conclusions drawn from © 2014 John Wiley & Sons Ltd
(P < 005). Both EMG activity and occlusal contact area increased gradually from LCR to NCR (to 177 20% and to 314 142 mm2, respectively). Finally, EMG activity still increased from NCR to HCR (to 445 37%) (P < 005), but the occlusal contact area remained stable (to 368 166 mm2). Occlusal contact points at left posterior, right posterior, anterior and total area were not significantly different between each task. This study showed that narrative instructions while recording the bite can result in largely stable occlusal contact area. An adequate narrative instruction may therefore contribute to taking a stable occlusal recording in natural dentition. KEYWORDS: narrative instruction, occlusal recording, occlusal point, occlusal area, tooth clenching Accepted for publication 12 December 2013
clinical research using measurements of occlusal characteristics provided by different systems, improved occlusal registration methods and materials are needed to meet these technical and clinical requirements (9, 14). Gurdsapsri et al. (15) measured occlusal contact during 10%, 30%, 70% and 100% maximum voluntary tooth contraction (MVC) and analysed the occlusal contact with each motor task. They showed that the occlusal contact area significantly increased with increasing clenching intensity. We showed that registration of occlusal contact for intercuspation using doi: 10.1111/joor.12134
INSTRUCTIONS ON OCCLUSAL CONTACT RECORDING silicone material is not stable at 10% MVC but were stable at 20% MVC and continued to be at 40% MVC. Therefore, it may be that adequate clenching force is required to register the appropriate occlusal contact (16). However, these are the results from controlled tooth clenching with EMG feedback, and it is unknown whether narrative instructions to patients can give stable and correct occlusal recording in the clinical setting. The aim of this study was to clarify the influence of different narrative instructions on the occlusal contact area and occlusal contact point using silicone materials and masticatory muscle activity using EMG in normal subjects. This may be helpful in the examination of occlusal-related disorders and for proper interocclusal recording in prosthodontic treatment.
Materials and methods Fig. 1. Diagram of study design.
Subjects Subjects were Japanese, had intact dentitions with no more than one missing tooth per quadrant (excluding third molars) and no pain suggestive of temporomandibular disorders (TMD) as defined by the Research Diagnostic Criteria for TMD (17). Subjects were excluded if they had received other treatment that could not be interrupted, if general health problems or periodontal disease were present. Twelve men and 12 women (mean age s.d.: 256 11 years) participated. Participants were informed about the experimental procedures, and informed consent was obtained prior to the experiment from all subjects. The Institutional Ethics Committee approved the study (EC11-014), and we followed the guidelines set out by the Declaration of Helsinki.
Experimental procedure During the experiment, each subject was comfortably seated upright in a dental chair with the head supported. Surface electrodes (NM319Y*) were placed 15 mm apart at a site 10 mm posterior to and parallel to the anterior border of the anterior lobe of the temporal muscles (TM), and in the central portion of the masseter muscles (MM) parallel to its anterior rim,
*Nihon Kohden, Tokyo, Japan. © 2014 John Wiley & Sons Ltd
and a common electrode was attached to the left wrist. As normal clenching record (NCR), intercuspal position was maintained with the narrative instruction, ‘Please bite down and keep the teeth together’. Occlusal contact was also recorded during clenching with the following three narrative instructions: ‘Please close your mouth and clench your teeth with minimal force’ (Minimal clenching record: MCR), ‘Please clench lightly’ (Light clenching record: LCR) and ‘Please clench hard’ (Hard clenching record: HCR). The sequence of measurement using these instructions was randomised (Fig. 1). Between each task, an interval of at least 3 min was imposed to avoid the influence of fatigue. At the end of the experimental session, three 3-s recordings of MVC were performed while the participant clenched in the maximum intercuspal position and the mean value of the three MVC recordings was calculated. During these tasks, MM and TM activities from both sides were also measured using a multitelemeter system (WEB-5000*) with the high cut frequency turned off, a time constant of 003 s and sensitivity of 05 mv/diV. Electromyography signals were recorded at a sampling frequency of 1 kHz and transferred to wave analysis software (Powerlab†).
†
AD Instruments, Sydney, NSW, Australia.
219
220
R . O B A R A et al. The occlusal recording was performed for each task with the aid of blue silicone material.‡ A silicone material was injected onto the occlusal surfaces of mandibular teeth. Before each measurement, the subjects were asked to close their mouth and to clench vertically with each narrative instruction for 1 min until complete setting of the silicone materials. The recording of occlusal contact with each narrative instruction was repeated twice in all subjects 1 week apart, and a coefficient of variation (CV) from repeated measurements was calculated for repeatability.
Electromyography analysis The EMG activity during each task was quantified by calculating the root mean square (RMS) amplitude in each of the 60 s epochs from both MM and TM EMG channels in all subjects. The relative ratio compared with the MVC (%MVC) of the MM and TM was calculated from the obtained RMS value in each task. To evaluate the stability of muscle activity, the initial 1 min during which complete setting of the silicone materials occurred was divided into four phases (Phase 1: 0–15 s, Phase 2: 16–30 s, Phase 3: 31–45 s and Phase 4: 46–60 s), and the relative ratios and CV value of the MM and TM in each task were calculated for each phase. The relative ratios of MM/MM and MM/TM in both sides to see the intra- and intersession differences of the EMG activity were calculated in each task. To evaluate repeatability between first and second EMG measurement, interclass correlation coefficient (ICC) at each task on MM and TM was calculated from %MVC of the MM and TM.
each task. The anterior zone and the left and right posterior zone were analysed separately following previous study (16). To evaluate repeatability between first and second occlusal contact area and point measurement, ICC was calculated from these values. Relationship between masticatory muscle activities and occlusal contact area in each task To compare the relationship between masticatory muscle activities and the occlusal contact area in each task, the mean relative ratios of the masticatory muscle activities were calculated from the RMS amplitude of the MM and TM on both sides, and defined as the mean relative ratio. Statistical analysis The RMS amplitudes and the relative ratio from the MM and TM EMG activities during all tasks, the relative ratios and CVs of the relative ratio from MM and TM EMG activities during the four phases in each task, and the relative ratios of MM/MM and MM/TM in both sides were analysed with Kruskal–Wallis ANOVA. The occlusal contact areas and points during all tasks were also analysed with Kruskal–Wallis ANOVA, and were followed by post-hoc Bonferroni tests to compensate for multiple comparisons. The level of statistical significance was set at P < 005. Mean values and 95% confidence intervals are presented in the text. All analyses were performed using an SPSS 12.0 package.¶
Results
Occlusal contact area and occlusal contact point analysis
Electromyography measurement
The silicone recording materials were trimmed to the appropriate thickness within 5 mm to keep the exact transmittance before the actual analysis. An occlusal analytic device (BITE EYE BE-I, GC§) was used for the analysis of the occlusal contact area and points (16). In the present study, occlusal contact area and point was defined as the thickness of silicone material was
Oral Rehabilitation
Journal of Oral Rehabilitation 2014 41; 218--225
Influence of different narrative instructions to record the occlusal contact with silicone registration materials R. OBARA*, O. KOMIYAMA†, T. IIDA†, T. ASANO†, A. DE LAAT‡ & M . K A W A R A † *Nihon University Graduate School of Dentistry at Matsudo, Matsudo, †Department of Oral Function and Rehabilitation, Nihon University School of Dentistry at Matsudo, Matsudo, Japan and ‡Department of Oral Health Sciences, Catholic University of Leuven, Leuven, Belgium
SUMMARY This study examined the influence of narrative instructions on the occlusal contact area, occlusal contact point and masticatory muscle activities in normal subjects. Twelve healthy men and 12 healthy women with no more than one missing tooth per quadrant participated. Surface EMG was recorded from the masseter and temporal muscle. As a control measurement, intercuspal position was maintained to produce a habitual clenching record (NCR) while the occlusal contact area and occlusal contact point was recorded by means of silicone material. Subsequently, the occlusal contact area was recorded with the narrative instruction for minimum clenching record (MCR), light clenching record (LCR) and strong clenching record (HCR). While the EMG activity (%MVC) increased modestly from MCR to LCR (from 93 20% to 115 15%), the occlusal contact area increased rapidly (from 172 113 mm2 to 268 156 mm2)
Introduction To diagnose occlusal-related disorders (1–3), occlusal tooth contacts have been recorded in a variety of groups with occlusal articulating paper (4, 5), occlusal strips or silk (6), black silicone material (7) and the pressure sensor sheet (8–10). As the nature of occlusal contacts is affected by biting pressure, some devices were developed to quantify the contact area together with bite force (11, 12) or by recording elevator muscle electromyography (EMG) (13). Considering the various clinical opinions and conclusions drawn from © 2014 John Wiley & Sons Ltd
(P < 005). Both EMG activity and occlusal contact area increased gradually from LCR to NCR (to 177 20% and to 314 142 mm2, respectively). Finally, EMG activity still increased from NCR to HCR (to 445 37%) (P < 005), but the occlusal contact area remained stable (to 368 166 mm2). Occlusal contact points at left posterior, right posterior, anterior and total area were not significantly different between each task. This study showed that narrative instructions while recording the bite can result in largely stable occlusal contact area. An adequate narrative instruction may therefore contribute to taking a stable occlusal recording in natural dentition. KEYWORDS: narrative instruction, occlusal recording, occlusal point, occlusal area, tooth clenching Accepted for publication 12 December 2013
clinical research using measurements of occlusal characteristics provided by different systems, improved occlusal registration methods and materials are needed to meet these technical and clinical requirements (9, 14). Gurdsapsri et al. (15) measured occlusal contact during 10%, 30%, 70% and 100% maximum voluntary tooth contraction (MVC) and analysed the occlusal contact with each motor task. They showed that the occlusal contact area significantly increased with increasing clenching intensity. We showed that registration of occlusal contact for intercuspation using doi: 10.1111/joor.12134
INSTRUCTIONS ON OCCLUSAL CONTACT RECORDING silicone material is not stable at 10% MVC but were stable at 20% MVC and continued to be at 40% MVC. Therefore, it may be that adequate clenching force is required to register the appropriate occlusal contact (16). However, these are the results from controlled tooth clenching with EMG feedback, and it is unknown whether narrative instructions to patients can give stable and correct occlusal recording in the clinical setting. The aim of this study was to clarify the influence of different narrative instructions on the occlusal contact area and occlusal contact point using silicone materials and masticatory muscle activity using EMG in normal subjects. This may be helpful in the examination of occlusal-related disorders and for proper interocclusal recording in prosthodontic treatment.
Materials and methods Fig. 1. Diagram of study design.
Subjects Subjects were Japanese, had intact dentitions with no more than one missing tooth per quadrant (excluding third molars) and no pain suggestive of temporomandibular disorders (TMD) as defined by the Research Diagnostic Criteria for TMD (17). Subjects were excluded if they had received other treatment that could not be interrupted, if general health problems or periodontal disease were present. Twelve men and 12 women (mean age s.d.: 256 11 years) participated. Participants were informed about the experimental procedures, and informed consent was obtained prior to the experiment from all subjects. The Institutional Ethics Committee approved the study (EC11-014), and we followed the guidelines set out by the Declaration of Helsinki.
Experimental procedure During the experiment, each subject was comfortably seated upright in a dental chair with the head supported. Surface electrodes (NM319Y*) were placed 15 mm apart at a site 10 mm posterior to and parallel to the anterior border of the anterior lobe of the temporal muscles (TM), and in the central portion of the masseter muscles (MM) parallel to its anterior rim,
*Nihon Kohden, Tokyo, Japan. © 2014 John Wiley & Sons Ltd
and a common electrode was attached to the left wrist. As normal clenching record (NCR), intercuspal position was maintained with the narrative instruction, ‘Please bite down and keep the teeth together’. Occlusal contact was also recorded during clenching with the following three narrative instructions: ‘Please close your mouth and clench your teeth with minimal force’ (Minimal clenching record: MCR), ‘Please clench lightly’ (Light clenching record: LCR) and ‘Please clench hard’ (Hard clenching record: HCR). The sequence of measurement using these instructions was randomised (Fig. 1). Between each task, an interval of at least 3 min was imposed to avoid the influence of fatigue. At the end of the experimental session, three 3-s recordings of MVC were performed while the participant clenched in the maximum intercuspal position and the mean value of the three MVC recordings was calculated. During these tasks, MM and TM activities from both sides were also measured using a multitelemeter system (WEB-5000*) with the high cut frequency turned off, a time constant of 003 s and sensitivity of 05 mv/diV. Electromyography signals were recorded at a sampling frequency of 1 kHz and transferred to wave analysis software (Powerlab†).
†
AD Instruments, Sydney, NSW, Australia.
219
220
R . O B A R A et al. The occlusal recording was performed for each task with the aid of blue silicone material.‡ A silicone material was injected onto the occlusal surfaces of mandibular teeth. Before each measurement, the subjects were asked to close their mouth and to clench vertically with each narrative instruction for 1 min until complete setting of the silicone materials. The recording of occlusal contact with each narrative instruction was repeated twice in all subjects 1 week apart, and a coefficient of variation (CV) from repeated measurements was calculated for repeatability.
Electromyography analysis The EMG activity during each task was quantified by calculating the root mean square (RMS) amplitude in each of the 60 s epochs from both MM and TM EMG channels in all subjects. The relative ratio compared with the MVC (%MVC) of the MM and TM was calculated from the obtained RMS value in each task. To evaluate the stability of muscle activity, the initial 1 min during which complete setting of the silicone materials occurred was divided into four phases (Phase 1: 0–15 s, Phase 2: 16–30 s, Phase 3: 31–45 s and Phase 4: 46–60 s), and the relative ratios and CV value of the MM and TM in each task were calculated for each phase. The relative ratios of MM/MM and MM/TM in both sides to see the intra- and intersession differences of the EMG activity were calculated in each task. To evaluate repeatability between first and second EMG measurement, interclass correlation coefficient (ICC) at each task on MM and TM was calculated from %MVC of the MM and TM.
each task. The anterior zone and the left and right posterior zone were analysed separately following previous study (16). To evaluate repeatability between first and second occlusal contact area and point measurement, ICC was calculated from these values. Relationship between masticatory muscle activities and occlusal contact area in each task To compare the relationship between masticatory muscle activities and the occlusal contact area in each task, the mean relative ratios of the masticatory muscle activities were calculated from the RMS amplitude of the MM and TM on both sides, and defined as the mean relative ratio. Statistical analysis The RMS amplitudes and the relative ratio from the MM and TM EMG activities during all tasks, the relative ratios and CVs of the relative ratio from MM and TM EMG activities during the four phases in each task, and the relative ratios of MM/MM and MM/TM in both sides were analysed with Kruskal–Wallis ANOVA. The occlusal contact areas and points during all tasks were also analysed with Kruskal–Wallis ANOVA, and were followed by post-hoc Bonferroni tests to compensate for multiple comparisons. The level of statistical significance was set at P < 005. Mean values and 95% confidence intervals are presented in the text. All analyses were performed using an SPSS 12.0 package.¶
Results
Occlusal contact area and occlusal contact point analysis
Electromyography measurement
The silicone recording materials were trimmed to the appropriate thickness within 5 mm to keep the exact transmittance before the actual analysis. An occlusal analytic device (BITE EYE BE-I, GC§) was used for the analysis of the occlusal contact area and points (16). In the present study, occlusal contact area and point was defined as the thickness of silicone material was
