Comparative Study Qualitative and Quantitative Techniques in the Study of Occlusion

Repeatability and reproducibility of 2 digital occlusal analyzers for measuring the right- and left-side balance of occlusal contact forces: An in vitro study

STATEMENT OF PROBLEM

Although different digital occlusal analyzers have been marketed, comparative studies are lacking.

PURPOSE

The purpose of this in vitro study was to compare the repeatability and reproducibility of 2 different digital occlusal analyzers (T-Scan and OccluSense) for measuring the right- and left-side balance of occlusal contact forces.

MATERIAL AND METHODS

The repeatability and reproducibility of the 2 digital occlusal analyzers for measuring the balance of occlusal contact forces were determined and compared by using the Gauge Repeatability and Reproducibility tests based on the International Organization for Standardization (ISO), ISO 5725-2 and ISO 5725-3 standards. Ten different dental casts were mounted in the maximum intercuspation position on a semi-adjustable articulator. Then, the balance of occlusal contact forces in each of the 10 articulated dental casts was measured 24 times with each of the 2 digital occlusal analyzers. In addition, as the OccluSense, unlike the T-Scan, does not have a centering support for the piezoelectric film sensor, measurements with it were performed without and with a custom-designed and manufactured centering support. Finally, the repeatability and reproducibility of both digital occlusal analyzers were determined and compared using the Gauge Repeatability and Reproducibility tests.

RESULTS

The repeatability and reproducibility tests revealed that only 0.8% of the variance of the measurements obtained with the T-Scan was due to repeatability and reproducibility (0.4% repeatability, 0.4% reproducibility). In contrast, 12% of the variance of the measurements obtained with the OccluSense was due to repeatability and reproducibility (2.2% repeatability, 9.8% reproducibility). However, when using OccluSense with the centering support, the variance decreased to 6.4% (2.8% repeatability, 3.6% reproducibility). According to the Automotive Industry Action Group classification, the repeatability and reproducibility of the T-Scan were good, those of the OccluSense poor, and those of the OccluSense with the centering support medium.

CONCLUSIONS

The repeatability and reproducibility of the T-Scan were significantly better than those of the OccluSense for measuring the balance of occlusal contact forces. Furthermore, the repeatability and reproducibility of the OccluSense were significantly improved when used with a device to center the piezoelectric film sensor between the incisors. Nevertheless, the repeatability and reproducibility of the T-Scan were better.

In vivo evaluation of T-Scan in quantifying occlusal contact

BACKGROUND

The T-scan system has been used previously to analyse occlusion, but the quantitative analysis of occlusal contact by T-Scan system has yet to be reported.

OBJECTIVES

To evaluate the reliability and validity of T-Scan system for quantitatively measuring occlusal contact area and occlusal contact number.

METHODS

Twenty-two individuals with normal occlusion, 11 men and 11 women, were recruited for the study. Two occlusal analysis methods, including silicone transmission analysis method (STA) and T-Scan occlusion analysis method (TSO), were used to make quantitative analysis to measure occlusal contact area (OCA) and occlusal contact number (OCN). A test-retest check was performed with an interval of 2 weeks. The values of intraclass correlation coefficients (ICC) between test-retest of each method were calculated for reliability evaluation. Pearson correlations analysis, paired t-tests, regression analysis and Bland-Altman analysis were performed for validity evaluation.

RESULTS

The ICC values of STA were greater than those of TSO for OCA while for OCN, ICC values of TSO were greater than STA. The higher OCA and OCN values were found in TSO compared with STA. Pearson's correlation coefficient indicated strong relations between TSO and STA (0.730-0.812) for OCA, while good relations between then (0.569-0.583) for OCN. Paired t-test showed a significant difference between the OCA and OCN values between TSO and STA. Bland-Altman analysis showed good agreement between OCA and OCN values of TSO and STA both in men and women. Regression analysis identified a linear correlation between OCA values obtained from these two methods.

CONCLUSIONS

T-Scan method showed strong reliability for measuring OCA and OCN quantitatively. Strong correlations were found between OCA values from TSO and STA method, but the validity of TSO for measuring OCN needs to be promoted.

CLINICAL SIGNIFICANCE

T-Scan system demonstrates good potential in quantitative analysis of occlusion, which will expand its clinical application.

Reliabilty of recording occlusal contacts by using intraoral scanner and articulating paper - A prospective study

OBJECTIVE

The recording of occlusal contacts is a pivotal step in many dental procedures, yet the lack of a standardized method could introduce clinical errors. The aim of this study was to compare the occlusal contacts recorded using a intraoral scanner to the contacts recorded using articulating paper. As a secondary outcome, the subjective clinical assessment made using the two methods was compared between different observers.

METHODS

Twenty-eight records were analysed for this study. Digital scan and intraoral photos of the coloured marks impressed by articulating paper were taken at the same time point for every patient. Using a standardized occlusal template, two operators recorded the number of occlusal contacts for every tooth provided by the two techniques. Then, 11 clinicians analysed the collected records and answered questions about the quality of the occlusions observed.

RESULTS

The statistical analysis showed significant differences between the number of contacts recorded by digital scan and those recorded by the photographed articulation marks, except in the case of the upper central incisors and first premolars. The Kappa Fleiss showed slight and fair agreement between clinicians when judging the occlusions.

CONCLUSION

The occlusal contacts recorded using the intraoral scanner and those recorded with the articulating paper did not match, and overall the clinicians showed low agreement when rating the recorded data.

CLINICAL SIGNIFICANCE

Despite of the great clinical importance of occlusal contact there is a lack of a precise method for recording and collecting occlusal contacts.

Positional influence of center of masticatory forces on occlusal contact forces using a digital occlusal analyzer

STATEMENT OF PROBLEM

Digital occlusal analyzers allow the recording of dental contact forces. Some authors assume a unique location for the center of contact forces at the position of maximum intercuspation, while others indicate variations in dental contact forces when recorded at different times of the day. Which approach is more appropriate is unclear.

PURPOSE

The purpose of this in vitro study was to analyze whether a change in the balance of masticatory forces influences the location of the center of contact forces and its magnitude.

MATERIAL AND METHODS

Three different dental casts, selected under dental criteria, were mounted in maximum intercuspation on a semiadjustable articulator equipped with a pattern indicating 9 different force application points (intersection point between 3 longitudinal rows and 3 transverse columns). A force of constant magnitude (169 N) was applied 10 times at each of the application points, and occlusal forces were recorded with a digital occlusal analyzer. Then, two variables were studied: the location of the center of contact forces and its magnitude. Each force application position (9 positions × 3 dental casts=27 in total) was repeated 10 times, and measured data were statistically analyzed with 2-way repeated measures ANOVA (α=.05) test.

RESULTS

The repeatability of the method indicated that the coefficient of variation mean was 0.37% in the location of the center of contact forces and that its magnitude was 3.70%. The 2-way repeated measures ANOVA test revealed statistically significant variations in the location of the center of contact forces and its magnitude, revealing that longitudinal changes of the application point of masticatory forces affected the magnitude of contact forces and that longitudinal and transverse changes of the application point of masticatory forces affected the location of the center of contact forces.

CONCLUSIONS

The location of the center of contact force and its magnitude provided by a digital occlusal analyzer at the position of maximum intercuspation are not necessarily unique to each articulated dental cast. Even if the intensity of the masticatory force remains unchanged, changes in its lateral or longitudinal balance also influence the result of the occlusion forces.

In vivo evaluation of the reliability and validity of three digital occlusion analysis methods

OBJECTIVES

The reliability and validity of three digital occlusion analysis methods was evaluated in vivo.

METHODS

The three method evalueated were:scanning of articulating paper marks (SA), dental prescale occlusal analysis system (DP) and a virtual occlusion constructed method (VO). A conventional silicone transmission method (ST) was used as the standard for comparison. Each of the 20 enroled human subjects was tested with the four methods. Retest of each method was performed at 2-week intervals. Occlusal contact area (OCA) and occlusal contact numbers (OCN) were calculated for analyses. For reliability evaluation, intraclass correlation coefficients (ICC) of the OCA and OCN values obtained from each method were compared. For validity evaluation, Pearson correlations coefficients, paired t-tests, regression analysis and Bland-Altman analysis were examined.

RESULTS

The ICC values of OCA and OCN were in the order: ST>SA>DP>VO. The highest OCA and OCN values were found ST while the lowest values were obtained from DP. Paired t-test identified a significant difference when OCA values obtained from the three digital methods were compared with ST, and between the OCN values of DP and ST. Pearson correlation showed high coefficients between ST and three digital methods (0.583-0.885 for OCA; 0.779-0.836 for OCN). A significant linear correlation was found between the results from ST and those from SA or VO. Bland-Altman analysis showed good agreement between OCN values of SA and ST, and between those of VO and ST.

CONCLUSIONS

The three digital occlusal analysis methods showed good reliability and validity for in vivo clinical application.

CLINICAL SIGNIFICANCE

The three digital occlusion analysis systems examined demonstrate good potential in in vivo quantitative analysis, with good reliability and validity. The use of these analytical methods should facilitate digital workflow in clinical practice.