Occlusal Contact Area Research Articles

Quantitative Comparison of Age-Related Development of Oral Functions During Growing Age.

This cross-sectional study aimed to investigate the age-related development of five major oral functions-tongue pressure, lip pressure, masticatory efficiency, bite force, and occlusal contact area-in subjects aged 5-20 years. Ninety-two subjects were divided into four age groups: 5-8, 9-12, 13-16, and 17-20 years. Oral functions were evaluated using standardized methods, including Chew Check Gum for assessing masticatory efficiency, Dental Prescale II for measuring occlusal force and contact area, JMS tongue pressure measuring device for evaluating tongue pressure, and Ripple-Kun for measuring lip pressure. Occlusal contact area, maximum bite force, tongue pressure, and masticatory efficiency gradually increased with age, whereas lip pressure remained stable. The occlusal contact area temporarily decreased between 5 and 12 years of age, likely due to the replacement of erupting lateral teeth. Some differences were observed between males and females; however, overall trends in oral function parameters were similar. Spearman's rank correlation analyses revealed significant positive correlations between age and occlusal contact area, bite force, tongue pressure, and masticatory efficiency. Oral function parameters exhibited different age-related development patterns. Occlusal contact area, maximum bite force, tongue pressure, and masticatory efficiency gradually increased with age. Interestingly, the occlusal contact area tended to reduce temporarily between 5 and 12 years of age due to the replacement of erupting lateral teeth. Conversely, lip pressure was almost stable during this period. Our findings provide valuable insights into the developmental patterns of oral functions during the growing years.

Light Clenching Differentially Affects Balance Ability According to Occlusal Contact Stability

Objectives: The purpose of this study was to determine the stability of occlusal contacts based on the left–right distribution of the occlusal contact area, divide participants into well-balanced and unbalanced groups, and clarify the effect of light clenching on the balance ability. Methods: Forty-one healthy men completed occlusal contact examinations with pressure-sensitive films, and the participants were allocated to the balanced occlusal contact (BOC) group or the unbalanced occlusal contact (UOC) group. The balance ability was measured using a center of gravity sway meter. The static balance in standing and dynamic balance using the cross test were assessed. Measurements were performed in the mandibular rest position (RP) or with light clenching (LC). Differences in the balance ability between the participant groups due to clenching and correlations between the static and dynamic balance were analyzed. Results: Differences in the balance ability due to clenching were observed only in the BOC group, with the static balance higher with LC, and the dynamic balance higher in the RP condition (p < 0.01). Significant correlations were observed between the static and dynamic balance except for the UOC group with LC (p < 0.01, p < 0.05). Conclusions: The results of this study suggested that occlusion affects the postural control when occlusal contact is stable but does not affect the postural control when occlusal contact is unstable.

In vivo evaluation of T-Scan in quantifying occlusal contact.

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. To evaluate the reliability and validity of T-Scan system for quantitatively measuring occlusal contact area and occlusal contact number. 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. 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. 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. T-Scan system demonstrates good potential in quantitative analysis of occlusion, which will expand its clinical application.

Effects of gum chewing training on occlusal force, masseter muscle thickness and mandibular shape: A randomised controlled clinical trial.

Masticatory muscle training by chewing gum can be performed easily and improve masticatory muscle function and strength. However, increased masticatory muscle activity and function may alter the mandibular shape. We aimed to investigate the effects of gum chewing training on the occlusal force, masseter muscle thickness (MMT) and mandibular shape in healthy adults. We conducted a prospective randomised controlled trial from January 2020 to September 2020 at the Yonsei University College of Dentistry. Fifty-eight participants were randomly assigned to the training and control groups. The training group chewed gum three times a day for 6 months, while the control group received no training. Changes in the maximum occlusal force and MMT were evaluated at baseline and after 1, 3 and 6 months. Changes in the mandibular shape were evaluated at baseline and after 6 months. The mean maximum occlusal force of the training group at 3 months was significantly higher than that at baseline, which was also significantly different from that in the control group (p < .001). As the maximum occlusal force increased, the occlusal contact area also increased (p = .020). There was no statistically significant difference in MMT or mandibular shape compared to the baseline. Mastication training using gum increases maximum occlusal force due to an increase in occlusal contact area but has no effect on MMT or mandibular shape.

Aspects of Occlusal Recordings Performed with the T-Scan System and with the Medit Intraoral Scanner.

Dental occlusion refers to the static and dynamic relationships that are established between the teeth of the two arches and is an important factor in the homeostasis of the dento-maxillary system. The objective of the present study was to compare two digital occlusal analysis systems: the T-Scan III system and the Medit I600 intraoral scanner. The study was carried out on 20 students from the Faculty of Dental Medicine Craiova, whose dental occlusion was assessed with the T-Scan III system and with the Medit I600 intraoral scanner. Dental occlusion was assessed in the maximum intercuspation position, the edge-to-edge protrusion position, and the edge-to-edge position in right and left laterotrusion. The images of the 2D occlusal contact areas obtained by both methods were converted to .jpeg format and then transferred to Adobe Photoshop CS6 2021 (Adobe Systems, San Jose, CA, USA) for comparison. The recorded data were statistically processed. Analyzing the data provided by the two digital occlusal analysis systems, it was found that the T-Scan III system provided data related to the amplitude of the occlusal forces, the surface on which they were distributed (the contact surface), the dynamics of the occlusal contacts, and the proportion in which they were distributed at the level of the two hemiarches, and the Medit I600 intraoral scanner performed an evaluation of the occlusal interface of the two arches, highlighting the extent of the contact areas with the degree of overlapping of the occlusal components. Although both methods of occlusal analysis recorded the highest values for the maximum intercuspation position, the results could not be compared. The two digital systems provide different data in occlusal analysis. As the T-Scan III system is considered the gold standard for occlusal analysis, more studies are needed to understand the data provided by the Medit I600 intraoral scanner and their significance.

Intraoral wear of PICN CAD-CAM composite restorations used in severe tooth wear treatment: 5-year results of a prospective clinical study using 3D profilometry

ObjectivesTo evaluate, in a prospective clinical study over 5 years with ex vivo 3D profilometry analyses, the intraoral wear of Polymer-Infiltrated Ceramic Network (PICN) CAD-CAM composite restorations used in severe tooth wear treatment with the One-Step No-Prep technique. Methods192 PICN (Vita Enamic) restorations on molars and premolars were included in a prospective clinical study involving patients treated according to the One-step No-prep protocol (n = 7). All patients showed clinical signs of bruxism. Replicas of restorations on molars and premolars were realized at each evaluation time (baseline and then every year up to 5 years) and scanned to perform 3D profilometry. Baseline and recall scans were superimposed with Geomagic Control software. The mean material wear was calculated for the full occlusal area (FOA) and for the occlusal contact area (OCA), respectively. Clinical evaluation of restorations was performed at recall. ResultsAt 5 years, the estimated mean material wear for FOA was inferior to the accuracy threshold of the profilometry measurement chain. For OCA, the estimated mean wear of the material was – 27.97 µm. This material wear was shown to be significantly influenced by time (p < 0.0001) and patient (p = 0.026), while the type of tooth (molar or premolar) had no influence. At 5 years, the survival and the success rates of restorations were 99.48% and 90.62%, respectively. SignificanceThe PICN material exhibits a low wear process in the treatment of severe tooth wear despite the presence of clinical signs of bruxism, and it constitutes a suitable material for the One-step No-prep technique.

ОЦЕНКА ПЛОЩАДИ ОККЛЮЗИОННЫХ КОНТАКТОВ У ПАЦИЕНТОВ С ПАРАФУНКЦИЯМИ ЗУБОЧЕЛЮСТНОЙ СИСТЕМЫ ДО И ПОСЛЕ СПЛИНТ- ТЕРАПИИ С ПОМОЩЬЮ ЦИФРОВОГО АППАРАТА T-SCAN

Abstract. Currently, dentists in the treatment of patients are increasingly encountering manifestations of parafunctions in the dental system. Most often, this manifests itself unconsciously in the form of daytime or nighttime bruxism and clenching. However, there is no reliable easily feasible method for diagnosing parafunctions. Digital dentistry is actively developing, which opens up new opportunities for assessing occlusive contacts. One of the most functional devices in this field is the T-scan. The aim of the study was to assess the area of facets of tooth erasure in patients with parafunctions before and after the use of occlusive splints using data from a digital T-scan device. In the study, occlusal contacts were registered, the sums of the facet areas of tooth erasure at the beginning of treatment and 6 months after splint therapy were calculated from the occlusiograms obtained. The results of the study showed that at the very beginning of the study, the values of the occlusal parameters of the right and left sides in patients in the group with bruxism and clenching prevail values of the left side of the dentition. The average sum of occlusal contact areas in patients with parafunctions was 310.02 mm2 on the left and 234 mm2 on the right. Upon repeated measurement, after splint therapy, the sum of the areas of occlusal contacts was 305.1 mm2 and 289.04 mm2 on the left and right, respectively. Thus, it is proved that the sum of the areas of occlusal contacts in patients on the left side of the dentition before the use of an occlusal splint significantly prevails over those after splint therapy. Occlusal forces between both sides of the lower jaw after the treatment have become more symmetrical and are close to a uniform distribution of force. This technique allows screening and monitoring of patients with bruxism and clenching.

The stress distribution of a primary molar tooth restored with stainless steel crown using different luting cements

BackgroundThe aim of this study is to evaluate the stress distributions of a primary molar tooth restored with a stainless steel crown (SSC) using resin and glass ionomer luting cements by Finite Element Analysis (FEA).MethodsOriginal DICOM data of a primary molar was used to create a 3D model. One model was prepared as a tooth model with SSC. A 30 μm cement layer was used in model. Two different luting cements were tested in the study: self-cure adhesive resin cement, and glass ionomer cement. Vertical and oblique loads of 330 N were applied to simulate maximum bite force and lateral forces in the occlusal contact areas of the models. Maximum von Mises stress values in the models were evaluated as MPa.ResultsThe maximum von Mises stress value was observed in the force application and general occlusal contact areas for all models. The maximum von Mises stress values were higher in the tooth model with SSC using self-cure adhesive resin cement (478.09 MPa and 214.62 MPa) than in the tooth model with SSC using glass ionomer cement (220.06 MPa and 198.72 MPa) in both vertical and oblique loading, respectively.ConclusionsDepending on the magnitude of the bite force on the SSC, fracture of the luting cement materials could occur if the stress exceeds the endurance limit of the luting cement. Cementation with glass ionomer cement may help to reduce stress levels in SSC restorations of primary molars in children.

Use of T-Scan III in analyzing occlusal changes in molar fixed denture placement

BackgroundThis study aims to analyze the longitudinal variation of occlusal force distribution prior to and after fixed restoration for molar full-crowns with T-SCAN III which provide reference for occlusal adjustment and long-term maintenance.MethodsWe enrolled a total of 20 patients who received conventional restorative treatment for molars. The occlusion examination was conducted in 3 stages (before placement, immediately after placement, and 3 months after placement) using T-SCAN III (Tekscan South Boston, MA, USA, 10.0) to examine and measure the occlusal contact areas of the full dentition.ResultsThe results indicated that the occlusal force distribution in the molar region of the patients changed before and after the fixed restoration, but the percentages of occlusal force in the dental arch of the molar did not differ significantly before and after the restoration (P > 0.05). Three months after the fixed restoration, the percentage of occlusal force in the restored dental arches of lateral teeth increased significantly (P < 0.05).ConclusionThe results of this study indicated that the occlusal forces of the patients changed with tooth movement and adaptation, which is mainly reflected in the increasing occlusal force. Quantitative occlusal force analysis using T-SCAN III occlusal analyzer can provide more objective and accurate data to effectively guide clinical occlusion adjustments.

Chewing Side Preference Related to Food Texture and Occlusal Contact Area.

To determine whether food texture affects chewing side preference (CSP) and to investigate the relationship between CSP and masticatory factors, such as occlusal contact area, bite force, and masticatory performance. Forty-seven adults (20 women and 27 men; mean age: 24 years) participated in this study. Three types of food (chewing gum, beef jerky, and peanuts) were provided to assess CSP. Occlusal contact area was measured at various ranges of interocclusal distance, and the bite force was measured. Masticatory performance was assessed according to the median particle size. Asymmetry indices of each measurement were calculated and analyzed using Pearson correlation coefficient (α &#61; .05). The CSP for beef jerky and peanuts were significantly correlated with each other, whereas the CSP for chewing gum was not correlated with other food. The proportion of participants who chewed equally on both sides was higher for chewing gum than for beef jerky. There was a significant correlation between the CSP for beef jerky and occlusal contact area, especially at interocclusal distance ranges of 0 to 89 μm and 0 to 109 μm (r &#61; 0.41). Bite force and masticatory performance were not significantly correlated with CSP. Food texture seemed to affect CSP, and masticatory laterality was greater for tough foods. Moreover, CSP for tough food was closely related to the occlusal contact area at an interocclusal distance level of about 0.1 mm.

Accuracy of Occlusal Contacts of All-Ceramic Single Crowns Designed by Virtual Articulators from a CAD/CAM System: A Preliminary Evaluation.

To compare the static and dynamic occlusion of all-ceramic single crowns designed by mechanical and virtual articulators, by evalua6ng the accuracy of occlusal contacts of prostheses designed by virtual articulators and the feasibility of clinical application of CAD/CAM virtual articulators. Nine subjects with an average age of 27 years who needed crown repair were recruited. After preparation of the all-ceramic crowns, two zirconia crowns were designed and fabricated through digital procedures and traditional methods. The intraoral scanner, Geomagic software, and T-Scan analyzer were used to analyze the occlusal contact points, areas, and the occlusal force percentage peak before the treatment and after the two crowns were temporarily fixed. There was a significant difference in the number of occlusal contact points and areas between the mechanical group and control group (preoperation group), but there was no obvious difference between the virtual group and control group. The occlusal contact overlapping areas of the virtual-control group were significantly larger than those of the mechanical-control group. The occlusal force percentage peak of the tested teeth was slightly larger in the mechanical group than in the virtual group. The posterior single crown designed by a virtual articulator restored the intercuspal occlusal better than one designed by a mechanical articulator, and it produced less dynamic occlusal interference. This finding suggests that virtual articulators can provide guidance for the design and adjustment of the occlusal surface of posterior single crown prostheses.

Comparison Between Maximum Bite Force on First Molar with Prosthesis and Contralateral First Molar Without Prosthesis

Background: Bite force is an indicator of the functional state of the masticatory system that results from the action of jaw elevator muscles modified by the craniomandibular biomechanics. Bite force measurement is essential in dental treatment as an extreme bite force on tooth may affect health of periodontium and increase risk of prosthesis fracture. A patient with low biting force may be helpful for the successful long-term outcome of prosthesis. A variety of devices has been used to record human bite force. Nowadays, sensitive electronic devices are used those are both accurate and precise enough. Recently, T-scan has been more popular to record the pattern of occlusion. The T-scan system precisely and dynamically records the occlusal contact time, force, and area in percentage. T-scan identify both force and timing which are the most fundamental parameters for measuring occlusion. The present study was designed to compare maximum bite force on first molar with prosthesis and contralateral first molar without prosthesis by using T-scan. Objectives: To compare maximum bite force (MBF) on first molar with prosthesis and contralateral first molar without prosthesis. Materials and Methods: This quasi-experimental type study was conducted in the Department of Prosthodontics, BSMMU. The patients were selected by a consecutive sampling technique, requiring permanent restoration in endodontically treated first molar on one side and natural first molar on contralateral side. The selected tooth was prepared for full veneer crown following standard procedure with armamentarium. Symptomless patients up to 3 months were measured bite force on cemented prosthesis and contralateral natural tooth. Bite force was measured with T-scan for three times with 30 sec interval and highest value was recorded in a data collection sheet for each patient to compare maximum bite force on first molar with prosthesis and contralateral first molar without prosthesis in the same patient. Result: The maximum bite force at the first molar without prosthesis was 14.30 ±4.2% and first molar with prosthesis was 12.05 ±3.55%. Tooth without prosthesis maximum bite force was significantly more than the tooth with prosthesis. Conclusion: Maximum bite force was significantly higher in tooth without prosthesis than the tooth with prosthesis. The difference of maximum bite force was not statistically significant in relation to gender, age and BMI.

Relationship between bite force, occlusal contact area, and three-dimensional facial soft tissue in dentofacial deformities.

This study aimed to investigate three-dimensional facial soft tissue dimensions, maximum bite force (MBF), and occlusal contact area in patients with DFD. In addition, we analyzed the relationship between MBF and the three-dimensional facial measurements. Thirty-two patients with skeletal Class III DFD and 20 patients with Class II DFD underwent a soft tissue evaluation using surface laser scanning, as well as MBF and occlusal contact area assessments. The DFD groups were compared with each other and with 25 healthy subjects. Significant morphological differences were found in the transversal, vertical, and anteroposterior dimensions between Class II DFD and Class III DFD. Both DFD groups presented an increased linear distance of chin height, which was strongly related with decreased MBF magnitude. The DFD groups exhibited lower MBF and occlusal contact area, with no significant differences between Class II and Class III DFD. The presence of DFD affected 3D measurements of facial soft tissue, causing variations beyond normal limits, lower MBF, and occlusal contact area in both Class II and Class III DFD patients. The vertical dimension might have influenced the lower MBF magnitude in the studied skeletal deformities.

Relationships between maxillofacial morphology and oral function on the habitual and non-habitual chewing sides.

This study aimed to investigate the relationships between reference planes and oral functions on the habitual and non-habitual chewing sides. Thirty-four subjects with no abnormalities in the maxillofacial region and oral functions were enrolled in this study. Relationships between angles between the reference plane (Frankfort horizontal plane, Camper's plane, and occlusal plane) and masticatory performance, occlusal force, and occlusal contact area by chewing side were examined. Regarding the measurement of reference planes, a creatively modified three-plane measuring device was used to measure angles between the reference planes. Images were taken from the right and left sides and angles between reference planes were measured. Masticatory performance was examined by measuring the amount of glucose extracted from a gummy jelly on the habitual and non-habitual chewing sides separately. Occlusal force and occlusal contact area were measured by occluding against pressure-sensitive film, and values on the habitual and non-habitual chewing sides were calculated and analyzed. The angle between Camper's plane and the occlusal plane correlated with masticatory performance on both the habitual chewing side (r = 0.47, P < .01) and the non-habitual chewing side (r = 0.36, P < .05). A correlation was observed between masticatory performance and occlusal force on the habitual chewing side (r = 0.46, P < .01). Masticatory performance became higher as occlusal plane inclination increased. This result represents essential knowledge for prosthetic treatment.

A finite element study on the risk of bone loss around posterior short implants in an atrophic mandible.

This study aimed to evaluate the risk of bone loss around single short molar crown-supporting implants in an atrophic mandible. Implants of different lengths (L = 4 or 6 mm) and diameters (Ø = 4.1 or 4.8 mm) were placed in the molar area of an atrophic mandible. Additional control mandible models were simulated for 4.1 mm diameter implants (L = 4, 6, 8, and 10 mm). A vertical masticatory load of 200 N was applied to three or six occlusal contact areas (3ca or 6ca) of the prosthetic crown. The bone strain energy density (SED) of 109.6 µJ/mm3 was assumed to be the pathological threshold for cortical bone. The peri-implant bone resorption risk index (PIBRri) was calculated by dividing the maximum SED of the crestal cortical bone by the SED pathological threshold. Increasing the implant length from 4 to 6 mm, implant diameter from 4.1 to 4.8 mm, and number of contact areas from 3 to 6 reduced the SED and PIBRri values by approximately 20%, 35%, and 40%, respectively, when comparing pairs of models that isolated a specific variable. All models with 6ca had a low bone resorption risk (PIBRri<0.8), while the Ø4.1 short implant with 3ca had a medium (0.8≤PIBRri≤1.0) or high (PIBRri>1.0) resorption risk. Increasing the diameter or occlusal contact area of a 4 mm short implant in an atrophic mandible resulted in reduced bone resorption risks, similar to or lower than those observed in a regular mandible with standard-length implants.

Distribution of main occluding area and associated factors in adolescents.

This study was designed to investigate the distribution of the main occluding area in adolescents. Furthermore, the importance of the main occluding area was clarified by examining its interrelationship with oral function and craniofacial morphology. A total of 102 patients were included in this study. The main occluding area was identified using a previously described method. Maximum occlusal force, occlusal contact area, lip-closing force, tongue pressure, and masticatory efficiency were measured to evaluate oral function. Craniofacial morphology was assessed using lateral cephalography. In terms of the degree of consistency of the main occluding area, the proportion of cases in which two matches were obtained among three trials was the highest. The most common main occluding area was the first molar. Regarding the anteroposterior position of the hyoid bone, the anteroposterior distance between the hyoid bone and the menton (Me-H) was significantly shorter in the group where the first molar was used for occlusion, relative to the group in which second premolar was used. The main occluding area in adolescents was less stable than that in adults and older adults; however, first molars accounted for most of the main occlusion areas, suggesting that the position of the hyoid bone might play a role in establishing their location.

3D quantitative analysis and SEM qualitative analysis of natural antagonist enamel opposing CAD-CAM monolithic zirconia or lithium disilicate tooth-supported crowns versus enamel opposing natural enamel.

This study aimed to evaluate the maximum vertical wear, volume wear, and surface characteristic of antagonist enamel, opposing monolithic zirconia or lithium disilicate crowns. The study comprised 24 participants (n = 12), who were randomly allocated to receive either a 5 mol% Y-TZP or a lithium disilicate crown in positions which would oppose the natural first molar tooth. The contralateral first molar along with its antagonist was considered as the enamel opposing natural enamel control. Data collection was performed using an intraoral scanner and polyvinylsiloxane impression. The means of the maximum vertical loss and the volume loss at the occlusal contact areas of the crowns and the various natural antagonists were measured by 3D comparison software. A scanning electron microscope was subsequently used to assess the wear characteristics. The one-year results from 22 participants (n = 11) indicated no significant differences when comparing the zirconia crown's antagonist enamel (40.28 ± 9.11 µm, 0.04 ± 0.02 mm3) and the natural enamel wear (38.91 ± 7.09 µm, 0.04 ± 0.02 mm3) (P > .05). Also, there is no significant differences between lithium disilicate crown's antagonist enamel (47.81 ± 9.41 µm, 0.04 ± 0.02 mm3) and the natural enamel wear (39.11 ± 7.90 µm, 0.04 ± 0.02 mm3) (P > .05). While some studies suggested that monolithic zirconia caused less wear on opposing enamel than lithium disilicate, this study found similar wear levels to enamel for both materials compared to natural teeth.

Features of the state of occlusion with partial loss of teeth (literature review)

This article provides an overview of literature sources devoted to the peculiarities of the state of occlusion in partial loss of teeth and modern methods of studying occlusive relationships. The clinical picture of partial tooth loss is quite diverse, while changes in occlusive relationships may occur due to the development of deformities of the dentition, the formation of traumatic occlusion, changes in the function of a group of teeth in the presence or absence of antagonists. An increase in the functional load on the preserved teeth entails a structural restructuring of occlusion, which at the initial stages of compensation manifests itself in the form of localized increased erasability of teeth with an increase in the area of occlusal contacts, enamel cracks, and then, as the reserve capabilities of the periodontal decrease, leads to the appearance of mobility and a change in the position of teeth.

Chewing efficiency and contact area discrepancies in Angle's class I and II malocclusion: A comparative study

ObjectiveThe study aimed to assess and compare both the chewing efficiency and the contact area between class I and class II of Angle’s malocclusions. Material and methodsA total of 120 individuals aged between 19 and 30 years were examined and were divided into two groups according to Angle’s class (Class I and class II). The chewing efficiency was quantified using the ViewGum software and two-colored chewing gum. The contact area was quantified using modeling wax and MATLAB software. All data were collected, then, analyzed using SPSS software 21. Data normality was checked through kurtosis test. Descriptive results were calculated. Matched sample t-tests were used to compare chewing efficiency measurements between right and left sides. Independent t-tests were used to compare chewing efficiency and the contact area between class I and class II of Angle’s malocclusions. Linear regression and Pearson correlation were used to assess the correlation between chewing efficiency and the contact area. The significance level was fixed at p = 0.05. ResultsFor group 1, the mean hue value on both sides was 0.086 ± 0.058. For group 2, it was 0.095 ± 0.055. The difference between both groups was statistically significant (p = 0.03). For group 1, the mean contact area was 49.91 ± 21.47 mm2. For group 2, it was 51.42 ± 19.76 mm2. The difference was statistically not significant (p = 0.4). The correlation between the contact area and the chewing efficiency in both groups was statistically significant and it was negative (in class I p = 0 and R = -0.616; in class II p = 0.01 and R = −0.408). ConclusionThe Chewing is better for patients with Angle’s Class I malocclusion. The contact area is higher. Larger occlusal contact area leads to higher masticatory efficiency. Further studies should be conducted.

Effect of digital complete dentures manufactured using the custom disk method on masticatory function

Statement of problemThe effect of using the custom disk method (CDM) for fabricating digital dentures on patients’ masticatory function should be studied to support its use in clinical practice. PurposeTo investigate the effect of digital dentures fabricated using CDM on patients’ masticatory function. Material and methodsThis single-center prospective clinical study included 20 patients with edentulous maxillary and mandibular arches who used a complete denture. The digital impression and complete denture manufacturing procedures using CDM have already been reported by Kanazawa et al. (2018) [32] and Soeda et al. (2022) [18] Thedigital dentures fabricated with CDM were delivered to the participants, and periodic adjustments were made until the patient could use the denture without pain. A color-changeable chewing gum, two types of gummy jellies that can evaluate the masticatory function, and pressure-sensitive sheets were used to evaluate the participants’ masticatory function at baseline, 1 month, and 6 months following adjustment of the new digital complete dentures fabricated with CDM. These masticatory function values had already been measured in the previous conventional dentures and were recorded as baseline values. ResultsThe study participants included 8 women and 12 men (mean age, 77.6 years). The color-changeable chewing gum analysis indicated that there was no significant improvement of masticatory function from baseline to 1 M (P = .083) and 6 M (P = .157).The gummy jelly analysis indicated no significant differences between the masticatory function baseline and 1 month (P = .387); however, a significant improvement was observed from baseline to 6 months (P = .020). Tests with Glucolum indicated a significant improvement from baseline to 1 month (P = .012) and 6 months (P = .003). The maximum bite force and occlusal contact area showed no significant difference at any time point. ConclusionsSignificant improvement in masticatory function was observed upon evaluation with gummy jelly and Glucolum 6 months after delivering the new digital complete dentures. Under limited conditions, the digital denture fabricated using CDM resulted in good recovery of the masticatory function in elderly edentulous patients. The present results combined with the cost-effectiveness and patient satisfaction associated with CDM indicate its clinical utility.