The effect of anterior repositioning splint therapy on maximum bite forces in patients with disc interference disorders.

OBJECTIVE: To evaluate the effect of anterior repositioning splint (ARS) on maximum bite force (MBF) values in patients with disc interference disorders (DID). MATERIAL AND METHODS: Twenty-two patients with disc interference disorders and 22 healthy subjects participated in to study. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I have been used to diagnose DID patients. All patients received ARS therapy for 6 weeks. The MBF measurement was performed with Flexi-Force piezo-resistive sensors for both healthy subjects and patients before and after ARS therapy. RESULTS: A significant difference was recorded by the increase of the mean MBF values after the use of the ARS in the patient with disc derangements (p < .05). CONCLUSIONS: APS therapy is efficient for eliminating pain and increasing MBF of the patients with DID. In addition, the use of FlexiForce sensors may be a practical solution to assess the bite force in the clinical setting.

Comparison of Simultaneously Recorded Computerized Occlusal Analysis and Surface Electromyographic Activity of Masticatory Muscles Between Patients with Unilateral TMD.

PURPOSE: To investigate the relationships among occlusion time, disclusion time, occlusal load distributions, and simultaneous electromyographic (EMG) recordings of the anterior temporalis (TA) and masseter (MM) muscles during centric and lateral movements in patients with unilateral temporomandibular disorder (TMD) pain and in asymptomatic control subjects. MATERIALS AND METHODS: Twelve healthy and 13 unilateral TMD subjects participated in the present study. The diagnosis of unilateral TMD was verified with vibrational analysis of the temporomandibular joints (TMJs) using the BioJVA (BioResearch Associates). Simultaneous computerized digital occlusal analysis using T-Scan III (Tekscan) and EMG activity of the MM and TA muscles using BioEMG III (BioResearch Associates) were performed in the intercuspal position and in right and left excursive movements. In intercuspal and lateral movement records, EMG activity of the masticatory muscles, occlusion time, disclusion time, and bite force distribution ratios were evaluated. RESULTS: No statistically significant differences were observed in occlusion time, disclusion time, or EMG activity of the MM and TA muscles between controls and patients with unilateral TMD in the intercuspal position. In unilateral TMD patients, disclusion time of the painful side was significantly higher than in the control group and compared to the nonpainful side (P < .05). Bite force distribution of the balancing side in TMD patients was shown to be statistically significantly higher values than in control subjects. EMG activity of the working-side TA muscle was higher than the nonworking side TA in controls and in the nonpainful side of TMD patients (P < .05). However, EMG activity of both the MM and TA muscles did not show a difference between the working side and nonworking side in unilateral TMD patients. CONCLUSION: In the intercuspal position, there was no difference in occlusion time, distribution of force, or EMG activity of the masticatory muscles observed between the control group and unilateral TMD pain patients. However, in lateral movements, the painful side of the unilateral TMD patients revealed increased balancing side TA activity, with higher disclusion time and balancing side force distribution.

Evolutionary Spectral Analysis of Temporomandibular Joint Sounds Before and After Anterior Repositioning Splint Therapy in Patients with Internal Derangement.

PURPOSE: To determine the effectiveness of anterior repositioning splint (ARS) therapy on elimination of temporomandibular joint (TMJ) sounds in patients with internal derangement. MATERIALS AND METHODS: A total of 26 patients with 44 TMJs with internal derangement according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were selected. These patients used an ARS for 6 weeks. The sounds of both the right and left TMJs were recorded with a specifically developed sound recording system before and after ARS therapy. The evaluation of sound was performed using evolutionary spectral analysis on the program MATLAB. Parameters such as sound type, amplitude, duration, and energy were evaluated in a time-frequency analysis. Changes in mean amplitude levels of opening/closing TMJ sounds before therapy and 6 weeks after insertion of splints were compared using paired-samples t test. The level of significance was set at 5%. RESULTS: The patients showed a decrease in the mean amplitude and energy values of opening/closing sounds after 6 weeks of ARS use (P < .05). According to evolutionary spectral analysis, the use of ARS was efficient for 7 of 19 right joints (37%) and 11 of 25 left joints (44%). CONCLUSION: The results suggest that the use of 6-week ARS reduced amplitude and energy parameters of TMJ sounds; however, it did not completely eliminate TMJ sounds.

In Vitro Cytotoxicity of Maxillofacial Silicone Elastomers: Effect of Nano-particles.

PURPOSE: Silicone elastomers are generally used for maxillofacial extraoral prostheses. The purpose of this in vitro study was to evaluate the cytotoxicity of different kinds of nanoparticles added to two types of maxillofacial elastomers. MATERIALS AND METHODS: A-2000 and A-2006 silicone elastomers were used. The silicone specimens were divided into eight groups according to the presence of additional nanoparticles (n = 18). The following represents the groups in the study: Group A: A-2000 silicone (control group); Group B: A-2006 silicone (control group); Group C: A-2000 silicone and the addition of titanium dioxide (TiO2 ); Group D: A-2006 silicone and the addition of TiO2 ; Group E: A-2000 silicone and the addition of fumed silica; Group F: A-2006 silicone and the addition of fumed silica; Group G: A-2000 silicone and the addition of silaned silica; Group H: A-2006 silicone and the addition of silaned silica. A paired sample t-test was used to analyze the cytotoxicity of each group after 24, 48, and 72 hours. RESULTS: Based on the results of the 24-hour analysis, the biocompatibility values of the (A-2006) fumed silica group were higher than those of the control groups. There was no statistically significant difference in A-2006 and A-2000 groups. The cytotoxicity values of the control groups and TiO2 (A-2000 silicone) elastomer groups increased at all test times; however, the cytotoxicity values of the TiO2 (A-2006), fumed silica (A-2006), silaned silica (A-2006), fumed silica (A-2000), and silaned silica (A-2000) groups increased significantly only from 24 to 48 hours. CONCLUSION: Nanoparticles of TiO2 , fumed silica, and silaned silica added to a commercial silicone-based elastomer used for fabrication of maxillofacial prostheses are nontoxic.

Effect of self and dual-curing on degree of conversion and crosslink density of dual-cure core build-up materials.

PURPOSE: Dual-cure core build-up resins have been developed to take advantages of both self and light-cured resin. The aim of present study was to determine the polymerization characteristics of self and dual-cured modes of dual-cure core build-up composites evaluating degree of conversion (DC) and crosslink density by measurement of glass-transition temperature (Tg) and hardness decrease in ethanol. METHODS: Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR) core build-up resins were selected. Twelve specimens for both composites were polymerized using quartz-halogen-tungsten light curing unit (QTH) and 12 specimens polymerized chemically. DC was determined by ATR-FTIR spectroscopy. TG/DTA analysis was performed to determine Tg. Microhardness value of specimens was determined by Vickers-tester before and after specimens stored in absolute ethanol for 24h. RESULTS: One-way ANOVA showed no different DC values between dual and self-cured mode of GR and dual-cured CLF composites had higher DC than self-cured mode. Tg and percentage of softening in ethanol values of GR and CLF revealed significant difference between self and dual-cured mode. CONCLUSIONS: In comparison of GR and CLF, DC showed no statistical difference in both curing modes. However, dual and self-cured GR has statistically higher Tg values and lower percentage of softening in ethanol than CLF. Polymerization characteristics of dual-cure core build-up composites have superiority in dual-cured mode than self-cured.

Effectiveness of disinfectants on the adherence of Candida albicans to denture base resins with different surface textures.

The aim of the present study was to compare the effects of some disinfectants, including ethanol extract of propolis (EEP), on the adhesion of Candida albicans to denture base resins. Seventy-two acrylic resin samples were prepared, half of which was polished and the other half was roughened. C. albicans strain ATCC 10231 was incubated on Sabouraud dextrose agar (SDA) at 37°C for 48 h. The adhesion period was completed by keeping the cells in this suspension for 90 min at 37°C. Specimens were then immersed in the following solutions: 1%, 2%, and 5% sodium hypochlorite; 4% chlorhexidine gluconate; and 10% EEP. Quantification of the antifungal activity of the chemical solutions was performed using the colorimetric MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay test. One-way ANOVA and post-hoc Tukey tests were performed to evaluate the effectiveness of chemical agents. Polished and roughened surfaces were compared using independent sample t-test. The mean surface roughness value was 0.35 (±0.04) µm for the polished group and 1.2 (±0.2) µm for the roughened group. The contact angles of both surfaces showed statistically significant difference, and 10% EEP solution exhibited significantly less removal of adherent viable C. albicans cells in both groups. All forms of sodium hypochlorite solutions yielded higher efficiency than 4% chlorhexidine gluconate and EEP solutions (P < 0.05). (J Oral Sci 58, 431-437, 2016).

The effect of two artificial salivas on the adhesion of Candida albicans to heat-polymerized acrylic resin.

PURPOSE: Xerostomia can diminish the quality of life, leads to changes in normal chemical composition of saliva and oral microbiata, and increases the risk for opportunistic infections, such as Candida albicans. Various artificial salivas have been considered for patients with xerostomia. However, the knowledge on the antifungal and antiadhesive activity of artificial saliva substitutes is limited. The aim of the present study was to evaluate influence of two artificial salivas on the adhesion of Candida albicans to the polymethylmethacrylate disc specimens. MATERIALS AND METHODS: Two commercial artificial salivas (Saliva Orthana and Biotene Oral Balance Gel) were selected. 45 polymethylmethacrylate disc specimens were prepared and randomly allocated into 3 groups; Saliva Orthana, Biotene-Oral Balance gel and distilled water. Specimens were stored in the artificial saliva or in the sterile distilled water for 60 minutes at 37℃. Then they were exposed to yeast suspensions including Candida albicans. Yeast cells were counted using ×40 magnification under a light microscope and data were analysed. RESULTS: Analysis of data indicated statistically significant difference in adhesion of Candida albicans among all experimental groups (P=.000). Findings indicated that Saliva Orthana had higher adhesion scores than the Biotene Oral Balance gel and distilled water (P<.05). CONCLUSION: In comparison of Saliva Orthana, the use of Biotene Oral Balance Gel including lysozyme, lactoferrin and peroxidase may be an appropriate treatment method to prevent of adhesion of Candida albicans and related infections in patients with xerostomia.

Resin cementation of zirconia ceramics with different bonding agents.

The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations.

The craniofacial morphology and maximum bite force in sleep bruxism patients with signs and symptoms of temporomandibular disorders.

OBJECTIVES: The purpose of the present study was to compare craniofacial morphology and bite force of bruxist patients with signs and symptoms of temporomandibular disorders. METHOD: Fourteen subjects with sleep bruxism and 14 healthy subjects participated. The signs and symptoms of the temporomandibular disorders were identified according to the Craniomandibular Index (CMI). Maximum bite force was measured using strain-gage transducers. Lateral cephalometric films were taken, and linear and angular measurements were performed. RESULTS: Bite force between bruxist and non-bruxist females was not significant, whereas males with bruxism revealed higher bite forces. None of the linear and angular measurements differed significantly between bruxist and non-bruxist males. However, higher mandibular corpus length and anterior cranial base length, and lower gonial angle were observed in bruxist females compared to non-bruxist females. Negative correlation between bite force and CMI values was found in both genders. DISCUSSION: Bruxist females had higher CMI values than bruxist males, which could lead to relatively lower bite forces.

Evaluation of the effect of two different occlusal splints on maximum occlusal force in patients with sleep bruxism: a pilot study.

PURPOSE: The occlusal splint has been used for many years as an effective treatment of sleep bruxism. Several methods have been used to evaluate efficiency of the occlusal splints. However, the effect of the occlusal splints on occlusal force has not been clarified sufficiently. The purpose of this study was to evaluate the effect of occlusal splints on maximum occlusal force in patients with sleep bruxism and compare two type of splints that are Bruxogard-soft splint and canine protected hard stabilization splint. MATERIALS AND METHODS: Twelve students with sleep bruxism were participated in the present study. All participants used two different occlusal splints during sleep for 6 weeks. Maximum occlusal force was measured with two miniature strain-gage transducers before, 3 and 6 weeks after insertion of occlusal splints. Clinical examination of temporomandibular disorders was performed for all individuals according to the Craniomandibular Index (CMI) before and 6 weeks after the insertion of splints. The changes in mean occlusal force before, 3 and 6 weeks after insertion of both splints were analysed with paired sample t-test. The Wilcoxon test was used for the comparison of the CMI values before and 6 weeks after the insertion of splints. RESULTS: Participants using stabilization splints showed no statistically significant changes in occlusal force before, 3, and 6 weeks after insertion of splint (P>.05) and participants using Bruxogard-soft splint had statistically significant decreased occlusal force 6 weeks after insertion of splint (P<.05). There was statistically significant improvement in the CMI value of the participants in both of the splint groups (P<.05). CONCLUSION: Participants who used Bruxogard-soft splint showed decreases in occlusal force 6 weeks after insertion of splint. The use of both splints led to a significant reduction in the clinical symptoms.

The bite force and craniofacial morphology in patients with acromegaly: a pilot study.

OBJECTIVES: Acromegaly is a metabolic disorder caused by increased growth hormone secretion. As a consequence of acromegaly some typical craniofacial morphology changes appear. This pilot study was conducted to compare the bite force and the characteristic size and shape of the craniofacial components of acromegalic patients with the healthy Turkish individuals. In addition, the correlations between bite force and craniofacial morphology of patients with acromegaly and control individuals were evaluated. STUDY DESIGN: The maximum bite force of the participants was recorded with strain-gage transducer. Lateral x-ray scans were made under standard conditions, in centric occlusion. On cephalograms, the linear and angular measurements was performed. RESULTS: Patients with acromegaly showed increased anterior and posterior total face height, ramus length, width of frontal sinuses, gonial angle and a negative difference between maxillary and mandibular protrusions. In addition, females with acromegaly showed larger lower anterior face height and sella turcica, decreased facial angle, increased mandibular plane angle. The cephalometric measurements, except one did not showed correlation with the bite force in acromegalic patients. In control group, significant correlations were observed between anterior total face height and anterior lower face height, mandibular plane angle and gonial angle. CONCLUSIONS: The greater changes were observed in the mandible. The maximum bite force of patients with acromegaly showed no difference from healthy individuals. The non-significant difference of bite force between healthy participants and acromegalic patients provide important information for dental treatment and prosthetic rehabilitation of acromegalic patients.

The evaluation of maximum bite force in the occlusal rehabilitation of patient with Angle Class III malocclusion: a case report.

The case report describes the occlusal rehabilitation of a male patient with Angle Class III malocclusion and its effect on maximum bite force. The main complaints of patient were masticatory difficulty and poor esthetic. The patient's expectations from the treatment were a good esthetic and function with a less invasive and relatively promptly way. Therefore, increasing of the occlusal vertical dimension (OVD) and then restoring the maxillary and mandibular teeth was chosen by the patient among the treatment options. At the beginning of treatment maximum bite force of patient was measured. Then an occlusal splint was provided to evaluate the adaptation of the patient to the altered OVD. Full mouth rehabilitation with metal ceramic restorations was made. After the completion of full mouth restoration, bite force measurement was repeated and patient exhibited increased maximum bite force. Full mouth restorative treatment in a patient with Class III malocclusion could be an effective treatment approach to resolve esthetic concern and to improve masticatory function related to maximum bite force.