Dynamic Quantitative Imaging of the Masseter Muscles in Bruxism Patients with Myofascial Pain: Could It Be an Objective Biomarker?

We aimed to investigate whether the collaboration of shear wave elastosonography (SWE) and B-mode ultrasonography (US) could be offered as diagnostic tools to assess the presence, severity, and progress of bruxism, as well as a biomarker for the effectiveness of treatment in daily clinical practice. The study was designed as a quantitative evaluation of the masseter muscles (MMs) of the clinically diagnosed bruxism patients suffering from myofascial pain and MMs of the healthy individuals. Clinical examinations were made according to the diagnostic criteria for temporomandibular disorders (DC/TMD), and pain was assessed using a visual analog scale (VAS). Painful MMs with VAS scores ≥ 4 were assigned to Group A, and healthy MMs were assigned to Group B. Also, the MMs of the painful bruxers were analyzed based on wearing occlusal splints. Group A was divided into two subgroups as splint users (Group AI) and non-users (Group AII). All the participants were scanned with dynamic US and SWE to quantify the size and stiffness of the MMs. Measurements of each muscle pair while the jaw is in a resting position (relaxation) and clenching position (contraction) were recorded. The significant differences in stiffness and thickness became visible in the relaxation state. Bruxism patients with myofascial pain had significantly harder and thinner MMs than healthy individuals. During the relaxation, the mean thickness and elasticity values were 9.17 ± 0.40 mm and 39.13 ± 4.52 kPa for Group A and 10.38 ± 0.27 and 27.73 ± 1.92 for Group B, respectively. Also, stiffer MMs were measured in Group AII (38.16 ± 3.61 kPa) than in Group AI (26.91 ± 2.13 kPa). In conclusion, the combination of SWE and US using a dynamic examination technique has the potential to be a valuable tool for the management of bruxism patients suffering from myofascial pain.

Wear evaluation of CAD-CAM dental ceramic materials by chewing simulation.

PURPOSE: To evaluate the wear of computer-aided design/computer-aided manufacturing (CAD-CAM) dental ceramic materials opposed by enamel as a function of increased chewing forces. MATERIALS AND METHODS: The enamel cusps of healthy human third molar teeth (n = 40) opposed by materials from CAD-CAM dental ceramic groups (n = 10), including Vita Enamic® (ENA), a polymer-infiltrated ceramic network (PICN); GC Cerasmart® (CERA), a resin nanoceramic; Celtra® Duo (DUO), a zirconia-reinforced lithium silicate (ZLS) ceramic; and IPS e.max ZirCAD (ZIR), a polycrystalline zirconia, were exposed to chewing simulation (1,200,000 cycles; 120 N load; 1 Hz frequency; 0.7 mm lateral and 2 mm vertical motion). The wear of both enamel cusps and materials was quantified using a 3D laser scanner, and the wear mechanisms were evaluated by scanning electron microscopy (SEM). The results were analysed using Welch ANOVA and Kruskal Wallis test (α = .05). RESULTS: ZIR showed lower volume loss (0.02 ± 0.01 mm3) than ENA, CERA and DUO (P = .001, P = .018 and P = .005, respectively). The wear of cusp/DUO [0.59 mm3 (0.50-1.63 mm3)] was higher than cusp/CERA[0.17 mm3 (0.04-0.41 mm3)] (P = .007). ZIR showed completely different wear mechanism in SEM. CONCLUSION: Composite structured materials such as PICN and ZLS ceramic exhibit more abrasive effect on opposing enamel due to their loss against wear, compared to uniform structured zirconia. The resin nanoceramic causes the lowest enamel wear thanks to its flexible nano-ceramic microstructure. While zirconia appears to be an enamel-friendly material in wear volume loss, it can cause microstructural defects of enamel.

Translucency of ceramic material in different core-veneer combinations.

STATEMENT OF PROBLEM: Understanding the translucency of ceramic materials is important to achieve good esthetics. Ceramic thickness is related to translucency; however, less information about core-veneer thickness in combination is available. PURPOSE: The purpose of this study was to investigate the translucency parameters of core-veneer thicknesses in 2 different ceramic materials. MATERIAL AND METHODS: A total of 56 ceramic disks of different thickness were fabricated as cores according to the manufacturer's recommendations and divided into groups (n=7). Each was veneered with its compatible veneer ceramic with a different thickness (0.2, 0.5, 0.7 mm). One group of each ceramic type was left without veneer. The groups were named according to core names (group IPS e.max Press [EP], group IPS Empress Esthetic [EE]), and numbers were given according to thickness combination: 1=(1.00+0.5); 2=(0.8+0.7); 3=(1.00); 4=(0.8+0.2). All surfaces were measured by profilometry to ensure consistency within the groups. A glass disk (1.5 mm) positive control (group P) and a metal core (1.5 mm) negative control (group N) were prepared. The translucency parameter values were calculated by using spectrophotometry to calculate the color differences of the specimens over black and white backgrounds. RESULTS: A 1-way ANOVA found significant differences among the translucency parameter values of the ceramic groups (P<.01). A 1-sample t test determined thickness consistency, and 1-way analysis was performed to ensure surface roughness consistency within the groups (P>.05). CONCLUSIONS: Total ceramic thickness affected the translucency; higher combined ceramic thickness resulted in lower translucency parameter values. When total thickness decreases, the translucency of core material has more effect than that of veneer material on translucency parameter values.

An alternative method for cementing laminate restorations with a micropulse toothbrush.

Because porcelain laminate veneers are fragile and thin, seating should be handled carefully, but complete seating is essential for a successful restoration. When a high-viscosity luting resin is chosen, high pressure will be needed to seat the veneer, which makes it possible to fracture the material with finger pressure. This technical report describes a straightforward and safe cementation technique for porcelain laminate veneers as well as for complete crown, inlay, and onlay restorations.

Three cases of elongated mandibular coronoid process with different presentations.

Abnormal elongation of the mandibular coronoid process is rare and its etiology is not yet elucidated. The aim of this report is to demonstrate and discuss the relationship between elongated mandibular coronoid process and limitation of mouth opening with cone beam computed tomography. Although the clinical characteristic of elongation of the coronoid process is mandibular limitation, in this report, one case had problem with mouth opening. Axial scans revealed that the distance between the coronoid process and the inner face of the frontal part of the zygomatic bone may cause limitation in mouth opening. In conclusion, instead of the length, the distance between the coronoid process and the inner face of the frontal part of the zygomatic bone may be the actual reason for limitation of mouth opening. This may prevent misdiagnosis.

Correlation of surface texture with the stainability of ceramics.

STATEMENT OF PROBLEM: Stainability is an important factor in the long-term clinical success of ceramic restorations. Contour adjustments on restoration surfaces cause differences in ceramic texture that may be affected differently by the staining agent. PURPOSE: The purpose of this study was to evaluate the surface texture obtained by different surface treatments relevant to the stainability of heat-pressed leucite-reinforced ceramic disk-shaped specimens. MATERIAL AND METHODS: Sixty-six ceramic disks (IPS Empress Esthetic) (15 × 2 mm) were prepared, glazed, and then assigned to 6 groups. All disks were abraded with a diamond rotary cutting instrument except group GG (control), which was not subjected to any procedure. Group R (rotary diamond cutting instrument) was left untreated after abrasion. Group PB was polished with an abrasive stone, a round polishing brush, and paste with felt wheels. Group PU was polished with 1.0- to 0.5-µm polishing pastes with a goat-hair brush. Group PS was polished with abrasive stone, silicon carbide polishers, and polishing paste with polishing disks. Group GR was reglazed. Surface roughness was measured with a profilometer and evaluated with scanning electron microscopy. A spectrophotometer was used before and after 12 days of immersion in a coffee solution to assess color difference. Data were analyzed by 1-way ANOVA, the Tukey honestly significant difference test, and the Pearson rank correlation tests (α=.05). RESULTS: Ra values of groups from highest to lowest were, in order, R, PB, PU, PS, GR, and GG (P<.01). Scanning electron microscope images and Ra values were compatible. The color difference (ΔE) values of groups from highest to lowest were, in order, R, PB, PU, PS, GR, and GG. A positive significant relationship of 65.6% between the Ra and ΔE values was found (P<.01). CONCLUSIONS: Ceramic staining may be related to surface texture. The use of appropriate polishing materials with compatible porcelain may reduce stainability.

Shear bond strength of resin cement to an acid etched and a laser irradiated ceramic surface.

PURPOSE: To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic. MATERIALS AND METHODS: Fifty-five ceramic blocks (5 mm × 5 mm × 2 mm) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at 37℃ for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05). RESULTS: Adhesion was significantly stronger in Group 2 (3.88 ± 1.94 MPa) and Group 3 (3.65 ± 1.87 MPa) than in Control group (1.95 ± 1.06 MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 (3.59 ± 1.19 MPa) and Control group. Shear bond strength was highest in Group 1 (8.42 ± 1.86 MPa; P<.01). CONCLUSION: Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique.

Removal of fractured laminate veneers with Er:YAG laser: report of two cases.

OBJECTIVE: To demonstrate the efficiency of Er:YAG laser for removal of laminate veneers in case of fracture. Primary modes of failure of porcelain laminate veneers were noted to be fracture, microleakage, or debonding. BACKGROUND DATA: One of the predisposing factors for the occurrence of fractures is heavy functional or parafunctional loading. METHODS: Removal of fractured laminate veneers with Er:YAG laser is proposed as a reliable method. Two cases are presented in which fractured laminate veneers were removed with Er:YAG laser. The parameters used for removal were set at 20 Hz/320 mJ, with water irrigation for 9 sec and the chisel-type laser tip was selected (1.2×0.4 mm, rectangular shape). The pulse width was 200 ms. RESULTS: The laminates were removed without any damage to the underlying tissue. The new restorations were reconstructed and both patients were taken under recall program at 6-month intervals. CONCLUSIONS: The removal of fractured laminate veneers with Er:YAG laser could be a suitable alternative in routine clinical use.

Effects of different surface treatments on stainability of ceramics.

STATEMENT OF PROBLEM: Final adjustments may result in a loss of ceramic glaze, a situation which must be corrected by reglazing or polishing to obtain clinically successful restorations; such restorations may be susceptible to staining. PURPOSE: The purpose of this study was to determine the stainability of ceramics exposed to coffee after different surface treatments and to correlate the surface roughness with the color differences. MATERIAL AND METHODS: Sixty-six ceramic (IPS e.maxCeram) disks (15 × 2 mm) were fabricated and glazed according to the manufacturer's instructions, then assigned to 6 groups. Group Glaze (Group G), the control, was not subjected to any procedure. All the others were abraded with a diamond rotary cutting instrument. Group Reglaze (Group R) was reglazed; others were polished with different polishing materials; Group Shofu (Group S) was polished with abrasive stone (Dura-Green Stones), coarse silicon polisher (Ceramaster Coarse), silicon polisher (CeraMaster), and polishing paste (Ultra II) with polishing disks (Super-Snap Buff Disks); Group Ultradent (Group U) was polished with 1.0 and 0.5-µm polishing pastes (Ultradent Diamond) with a goat hair brush (Jiffy) and Group Bredent (Group B) was polished with an abrasive stone (Diagen turbo grinder), a round polishing brush (Abraso-fix), and polishing paste (Diamond) with felt wheels. Group Diamond rotary cutting instrument (Group D) was not treated after abrasion with a diamond rotary cutting instrument. Surface roughness was evaluated by profilometer (n=10), and 1 specimen from each group was evaluated by scanning electron microscopy (SEM). Color difference was measured by a spectrophotometer before and after 12 days of immersion in a coffee solution. Data were analyzed by 1-way ANOVA, the Tukey HSD test, and the Pearson rank correlation tests (α=.05). RESULTS: The surface roughness (Ra) values were ordered from the highest to the lowest value, which were Group D, B, U, S, R, and G, respectively. Significant differences among groups (P<.01) were found, except for G and R. There were no significant differences between the color difference values of Groups G and R, both of which were significantly lower than the other groups (P<.01). Group D showed the highest ΔE values (>2), which is considered clinically unacceptable (P<.01). No significant differences were found among the S, U, and B groups. There was an 83% positively significant relationship between Ra and ΔE values (P<.01). Rough surfaces stained more after coffee immersion than did smooth surfaces. CONCLUSIONS: Surface treatments affected surface roughness and color stability. Smooth surfaces showed better color stability after discoloration. Ceramic staining may be related to surface texture changes after different surface treatments.

Comparison of the marginal fit of different coping materials and designs produced by computer aided manufacturing systems.

In this study, marginal adaptations of different copings fabricated with CAD/CAM or MAD/CAM were analysed. Celay and Zirkonzahn groups were fabricated by MAD/CAM, LAVA and DC-Zircon groups were fabricated by CAD/CAM. Casting metal copings were used as the control group. An implant abutment that was embedded in octagonal acrylic block was used to prepare the copings. Sixteen previously established points were marked and the measurements were performed with the stereomicroscope (at × 150). The marginal fit of the samples were evaluated by calculating the mean measurements of each 16 points. The statistical analysis was performed by Tukey multiple comparisons test at 95% confidence interval. The groups can be summarized as follows in terms of marginal gap, from the lowest to highest: LAVA (24.6 ± 14.0 µm)

Use of Stafne's mandibular defect in improving retention of mandibular complete dentures.

In 1942, Stafne was the first to report radiographic findings of "static bone cavities" situated near the angle of the mandible. The typical radiographic appearance of Stafne's mandibular defect is a radiolucency below the inferior alveolar canal, between the mandibular premolars and the angle of the mandible. Stafne's mandibular defect ranges from 10 mm to 30 mm in diameter. The size has been shown to be remarkably constant in diagnosed lesions followed over time. In the majority of cases, the lesion is symptomless. Routine surgical exploration is not indicated. It is suggested that the lesion is a radiographic rather than a pathological entity; therefore, consideration was given to making use of these anatomical retentive areas in a prosthetic manner. In this article, a literature review of Stafne's mandibular defect is presented and attempts to improve the retention and stability of the lower complete dentures by using this anatomical entity are described.

Using tissue conditioner material in neutral zone technique.

The looseand unstable lower complete denture is a common problem faced by denture patients. One method used to solve this problem is the neutral zone technique. The neutral zone is the area where the displacing forces of the lips, cheeks and tongue are in balance. In the clinical report presented here, a severely resorbed lower alveolar ridge was treated by determining the neutral zone with tissue conditioner material (Visco-gel, Dentsply Ltd., Weybridge, U.K.). The neutral zone approach with Visco-gel is a more practical and economically feasible treatment for patients having atrophic mandibular ridge.

Elongated mandibular coronoid process as a cause of mandibular hypomobility.

There are multiple factors in cases of mandibular hypomobility. One of these factors is elongated coronoid process. Two cases are presented to illustrate elongated coronoid process leading to mandibular hypomobility to help prevent misdiagnosis by clinicians. Coronoid process elongation is a rare condition. Both cases reported here had pulpitis on the teeth, however endodontic treatment could not be performed due to the restricted mouth opening in both cases. There were clinical findings of restricted range of motion, especially during protrusive movements. The restrictive movements did not cause pain for either patient, and the patients were not aware of their restricted mouth opening. Panoromic radiographs were taken and evaluated. The radiographs showed elongated coronoid process bilaterally. Three-dimensional computerized tomography was taken in one case only, due to the patient's financial restrictions. In cases of restricted mandibular opening, elongated coronoid process must be considered when diagnosing the cause.

Radiological evaluation of the styloid process in young adults resident in Turkey's Yeditepe University faculty of dentistry.

OBJECTIVES: This study evaluated and classified the radiographic appearance of the styloid process (SP) patterns of calcification according to subject gender. The relationship between SP length and the limits of mandibular protrusion was studied. STUDY DESIGN: The panoramic radiographs of 55 young adults were analyzed. Elongated SPs were classified with the radiographic appearance based on length, morphology, and calcification pattern. The data were analyzed by using chi-squared and 1-way ANOVA with significance set at P < .05. RESULTS: "Elongated" (Type I) SP with "calcified outline" was the most frequent SP type and calcification pattern. No correlation was found between SP type and calcification pattern and subject gender. No differences were proven based on laterality of the SP. A relationship between mandibular protrusive movement and SP calcified length was not proven. CONCLUSION: Elongation of calcification of SP in young adults is common with no correlation to gender, laterality, or mandibular protrusive limitation. "Type I" with "calcified outline" of the SP was observed most frequently in the population studied.