Purpose: The aim of this study was to present the current concept of bone quality based on the proposal by the National Institutes of Health (NIH) and some of the cellular and molecular factors that affect bone quality.

Study selection: This is a literature review which focuses on collagen, biological apatite (BAp), and bone cells such as osteoblasts and osteocytes.

Results: In dentistry, the term "bone quality" has long been considered to be synonymous with bone mineral density (BMD) based on radiographic and sensible evaluations. In 2000, the NIH proposed the concept of bone quality as "the sum of all characteristics of bone that influence the bone's resistance to fracture," which is completely independent of BMD. The NIH defines bone quality as comprising bone architecture, bone turnover, bone mineralization, and micro-damage accumulation. Moreover, our investigations have demonstrated that BAp, collagen, and bone cells such as osteoblasts and osteocytes play essential roles in controlling the current concept of bone quality in bone around hip and dental implants.

Conclusion: The current concept of bone quality is crucial for understanding bone mechanical functions. BAp, collagen and osteocytes are the main factors affecting bone quality. Moreover, mechanical loading dynamically adapts bone quality. Understanding the current concept of bone quality is required in dentistry.

Purpose: The aim of this study was to compare the accuracy of different laboratory scanners using a calibrated coordinate measuring machine as reference.

Methods: A sand blasted titanium reference model (RM) was scanned with an industrial 3D scanner in order to obtain a reference digital model (dRM) that was saved in the standard tessellation format (.stl). RM was scanned ten times with each one of the tested scanners (GC Europe Aadva, Zfx Evolution, 3Shape D640, 3Shape D700, NobilMetal Sinergia, EGS DScan3, Open Technologies Concept Scan Top) and all the scans were exported in.stl format for the comparison. All files were imported in a dedicated software (Geomagic Qualify 2013). Accuracy was evaluated calculating trueness and precision.

Results: Trueness values (μm [95% confidence interval]) were: Aadva 7,7 [6,8–8,5]; Zfx Evolution 9,2 [8,6–9,8]; D640 18,1 [12,2–24,0]; D700 12,8 [12,4–13,3]; Sinergia 31,1 [26,3–35,9]; DScan3 15,6 [11,5–19,7]; Concept Scan Top 28,6 [25,6–31,6]. Differences between scanners were statistically significant (p<.0005). Precision values (μm [95% CI]) were: Aadva 4,0 [3,8–4,2]; Zfx Evolution 5,1 [4,4–5,9]; D640 12,7 [12,4–13,1]; D700 11,0 [10,7–11,3]; Sinergia 16,3 [15,0–17,5]; DScan3 9,5 [8,3–10,6]; Concept Scan Top 19,5 [19,1–19,8]. Differences between scanners were statistically significant (p<.0005).

Conclusions: The use a standardized scanning procedure fabricating a titanium reference model is useful to compare trueness and precision of different laboratory scanners; two laboratoryscanners (Aadva, Zfx Evolution) were significantly better thatother tested scanners.

Purpose: The aim of this study was to investigate the correlation between bone density of the edentulous mandibular ridge crest and residual bone height in edentulous subjects using multidetector computed tomography (MDCT) images.

Methods: A total of 194 bilateral MDCT images from 97 individuals with an edentulous mandible were selected for analysis. The residual ridge ratio (RRR), the CT values at the residual ridge crest, and the CT values at the lowest point of the mandible measured from MDCT images at molar region. RRR was classified into the three groups (Group 1: >2.0, Group 2: 1.5-2.0, Group 3: <1.5). Bone density at the residual ridge crest was evaluated by calculating the ratio of the CT value at the lowest point of the mandible and the CT value of the residual ridge crest ("ratio of CT values"). The relationship between the height of the residual ridge and the bone density of the residual ridge crest was evaluated by ratio of CT values.

Results: Median ratio of CT values was 0.62 in Group 1, 0.70 in Group 2, and 0.84 in Group 3, indicating significant differences between all 3 groups (p<0.05). The correlation coefficient for RRR and residual ridge crest bone density was -0.54 in males and -0.55 in females, implying a moderate correlation for both males and females.

Conclusions: The present results suggest a negative correlation between residual bone height and the bone density of the edentulous mandibular ridge crest.

Purpose: We aimed to clarify whether people stare at non-esthetic restorations by analyzing the gaze point of laypersons looking at mouth images with intraoral non-esthetic restoration.

Methods: The gaze points of 47 laypersons who do not visit dentists were measured using an eye tracker. The stimuli were 18 photographs of mouths with or without a non-esthetic tooth restoration, each randomly shown for 5s. The analysis sites included a tooth with nonesthetic restoration and the same tooth on the opposite side of the mouth. We measured the proportion of participants who first fixated on each analysis site, and total fixation time for each site.

Results: In images without non-esthetic restorations, a similar proportion of participants first fixated on each analysis site. However, more participants first fixated on non-esthetic restorations when the images contained them. Total fixation time for each site did not differ significantly between the left and right sides in the images without non-esthetic restoration (P>0.05). Participants fixated on the non-esthetic restoration significantly more in the images containing them (P<0.01).

Conclusions: Within the limitations of this study, the present findings suggest that in photographs of the mouth with non-esthetic restoration on either side, the non-esthetic restoration is first gazed before the opposite side. In addition, the non-esthetic restoration is gazed longer than the opposite side, and there was no major difference in the fixation time regarding the state of non-esthetic restoration.

Purpose: To assess the time course of chewing-stimulated salivary flow after oral atropine administration, and determine the association between chewing-stimulated salivary flow and mixing ability using color-changeable chewing gum in dentate adults.

Methods: Ten healthy dentate adults were administered 1mg oral atropine to induce mouth dryness. The subjects' chewing-stimulated salivary flow was assessed using the Saxon test. They were then asked to rinse their mouth with tap water for 15s, and to chew on colorchangeable chewing gum for 60s at a constant rate of 60 cycles per min. This procedure was performed before, and at 10-min intervals for up to 120min after the atropine administration. The experiment was repeated after 1 week. Steel's test was used to compare the chewingstimulated salivary flow rates at each time point after atropine administration with the baseline value. The effect of the stimulated salivary flow rates on the degree of color change was analyzed using linear mixed effects models, with the stimulated salivary flow rates as fixed factors and subjects as the random factor.

Results: Chewing-stimulated salivary flow showed a significant decrease from 50 to 120min after oral atropine administration (P<0.05) and the amount of chewing-stimulated salivary flow had a significant effect on the color change of the color-changeable chewing gum (P<0.001).

Conclusions: We observed a decrease in stimulated salivary flow after orally administering 1mg atropine, and a positive association between mixing ability using color-changeable chewing gum and chewing-stimulated salivary flow in dentate subjects.

Purpose: This study combines clinical investigation with finite element (FE) analysis to explore the effects of buccal bone thickness (BBT) on the morphological changes of buccal bone induced by the loaded implant.

Methods: One specific patient who had undergone an implant treatment in the anterior maxilla and experienced the buccal bone resorption on the implant was studied. Morphological changes of the bone were measured through a series of cone-beam computed tomography (CT) scans. A three-dimensional heterogeneous nonlinear FE model was constructed based on the CT images of this patient, and the in-vivo BBT changes are correlated to the FE in-silico mechanobiological stimuli; namely, von Mises equivalent stress, equivalent strain, and strain energy density. The anterior incisory bone region of this model was then varied systematically to simulate five different BBTs (0.5, 1.0, 1.5, 2.0, and 2.5mm), and the optimal BBT was inversely determined to minimize the risk of resorption.

Results: Significant changes in BBTs were observed clinically after 6 month loading on the implant. The pattern of bone resorption fell into a strong correlation with the distribution of mechanobiological stimuli onsite. The initial BBT appeared to play a critical role in distributing mechanobiological stimuli, thereby determining subsequent variation in BBT. A minimum initial thickness of 1.5mm might be suggested to reduce bone resorption.

Conclusions: This study revealed that the initial BBT can significantly affect mechanobiological responses, which consequentially determines the bone remodeling process. A sufficient initial BBT is considered essential to assure a long-term stability of implant treatment.

Purpose: The aim of this study was to evaluate the fit and mechanical stability of conventional versus passive fitting 3-unit fixed dental prosthesis (FDP) screw-retained on implants.

Methods: Twenty acrylic models, each with two embedded implants, were fabricated and functioned as patient-models. Impressions were taken and 20 all-ceramic FDPs were prefabricated on the plaster casts. Respectively 10 FDPs were fixed on the plaster casts (group 1) and on the patient-models for passive fitting (group 2). The fit of each FDP was checked on the patient-model by means of visual control (grades 1-10) and microscopic examination. Furthermore, specimens were artificially aged for possible prosthodontic failures, followed by a fracture strength test.

Results: Group 2 [1.4 (±0.3)] showed significantly (p<0.001) better results in the visual examination of the marginal fit compared to group 1 [6.3 (±2.4)]. The microscopic marginal misfit was 160μm (±80μm) at the abutment margin and 150μm (±80μm) at the axial wall of the abutment for group 1, respectively, 0μm and 0μm up to 17μm for group 2 (p<0.001). No failure of the FDPs could be observed during artificial aging in both groups. The fracture load showed no significant difference (p=0.60) between group 1 [2583N (±664N)] and group 2 [2465N (±238N)].

Conclusions: Visual and microscopic examination detected huge differences in marginal fit between groups 1 and 2. However, no statistically verifiable differences could be detected in long-term stability of implant-supported FDPs irrespective of the fit.

Purpose: The purpose of this study was to determine the effect of the curing condition (i.e., the curing mode and restoration thickness) on the tensile bond strength of a dual-cure resin cement applied to dentin.

Methods: Indirect composite resin disks (1, 2, and 3mm in thickness) were prepared. The irradiance of a halogen light curing unit through each disk was measured by a curing radiometer. A measurement was also taken for the condition with no disk. Following this, two dual-cure resin cements, Panavia F2.0 and Panavia V5, were polymerized in either dualcure mode or self-cure mode to bond the composite resin disk to the flat dentin surface. The specimens were sectioned and subjected to a microtensile bond strength (μTBS) test after 24h of water storage. The data were statistically analyzed by two-way ANOVA followed with multiple comparisons by post-hoc Tukey's test (α=0.05).

Results: The irradiance values [mW/cm²] measured through indirect composite resin disks were 600 (0mm), 200 (1mm), 90 (2mm), and not detected (3mm). Two-way ANOVA indicated that both the curing condition and the type of resin cement affected the μTBS (p<0.001). The μTBS results for Panavia V5 bonded to dentin were significantly higher than those of Panavia F2.0 bonded to dentin (p<0.05).

Conclusions: The curing condition affected the tensile bond strength of the dual-cure resin cements to dentin. A newly developed resin cement, Panavia V5, showed higher dentin bonding than Panavia F2.0 in both dual- and self-cure modes.

Purpose: The purpose of this study was to clarify the relationship between masticatory performance using a gummy jelly and masticatory movement.

Methods: Thirty healthy males were asked to chew a gummy jelly on their habitual chewing side for 20s, and the parameters of masticatory performance and masticatory movement were calculated as follows. For evaluating the masticatory performance, the amount of glucose extraction during chewing of a gummy jelly was measured. For evaluating the masticatory movement, the movement of the mandibular incisal point was recorded using the MKG K6-I, and ten parameters of the movement path (opening distance and masticatory width), movement rhythm (opening time, closing time, occluding time, and cycle time), stability of movement (stability of path and stability of rhythm), and movement velocity (opening maximum velocity and closing maximum velocity) were calculated from 10 cycles of chewing beginning with the fifth cycle. The relationship between the amount of glucose extraction and parameters representing masticatory movement was investigated and then stepwise multiple linear regression analysis was performed.

Results: The amount of glucose extraction was associated with 7 parameters representing the masticatory movement. Stepwise multiple linear regression analysis showed that the opening distance, closing time, stability of rhythm, and closing maximum velocity were the most important factors affecting the glucose extraction.

Conclusion: From these results it was suggested that there was a close relation between masticatory performance and masticatory movement, and that the masticatory performance could be increased by rhythmic, rapid and stable mastication with a large opening distance.

Purpose: The purpose of this study was to clarify the effect of the bitterness of food on muscular activity and masticatory movement.

Methods: Twenty healthy subjects were asked to chew a non-bitter gummy jelly and a bitter gummy jelly on their habitual chewing side. The masseter muscular activity and the movement of mandibular incisal point were recorded simultaneously. For all cycles excluding the first cycle, parameters representing the muscular activity (total integral value and integral value per cycle) and masticatory movement (path, rhythm, and stability) were calculated and compared between the two types of gummy jellies.

Results: The total integral value of masseter muscular activity during the chewing of bitter gummy jelly was significantly smaller than during the chewing of non-bitter gummy jelly, however, no definite trends in the integral value per cycle and the stability of movement were observed. The parameters representing the movement path tended to be small during the chewing of bitter gummy jelly than during the chewing of non-bitter gummy jelly. The masticatory width was significantly smaller during the chewing of bitter gummy jelly. The parameters representing the rhythm of movement were significantly longer during the chewing of bitter gummy jelly than during the chewing of non-bitter gummy jelly.

Conclusion: From these results it was suggested that the bitterness of food does not affect the integral value per cycle or the stability of the masticatory movement, but it does affect the movement path and rhythm, with narrowing of the path and slowing of the rhythm.

Purpose: The aim of this study was to quantify masseter muscle stiffness in patients with masticatory myofascial pain.

Methods: Stiffness was measured using shear wave elastography, which expresses stiffness as shear wave velocity (Vs). A phantom study was conducted to confirm the reliability of the measuring device. The study participants were 26 females with bilateral masseter muscle pain who were classified into either Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) group Ia (myofascial pain; n=13) or RDC/TMD group Ib (myofascial pain with limited opening; n=13). Healthy controls consisted of 24 female volunteers with normal teeth and jaws, who were not classified into groups I/II/III by RDC/TMD.

Results: Muscle stiffness was 1.96m/s (12.5kPa) in 13 patients in group Ia, 2.00m/s (13.0kPa) in 13 patients in group Ib and 1.27m/s (5.25kPa) in 24 control subjects. Vs was significantly greater in groups Ia and Ib than in the control group (p<0.05). Characteristic pain intensity (CPI) became clear as an independent factor impacting Vs (partial regression coefficient= 0.714; multiple regression analysis, p<0.05). Masseter muscle stiffness was positively correlated with CPI (p<0.05) and negatively correlated with maximum assisted mouth opening (p<0.05) and painless mouth opening (p<0.05).

Conclusion: Shear wave elastography is useful to quantify masticatory muscle stiffness. Masseter muscle stiffness of females measured using shear wave elastography was about two-fold greater in group Ia and Ib than in the healthy control group.

Purpose: Implant-supported overdentures are an alternative predictable rehabilitation method that has a high impact on improving the patient's quality of life. However, some biological complications may interfere with the maintenance and survival of these overdenture implants. The goal of this article was to assess the factors that affect periimplant success, through a hypothetical prediction model for biological complications of implant overdentures.

Methods: A retrospective observational, prevalence study was conducted in 58 edentulous Caucasian patients rehabilitated with implant overdentures. A total of 229 implants were included in the study. Anamnestic, clinical, and implant-related parameters were collected and recorded in a single database. "Patient" was chosen as the unit of analysis, and a complete screening protocol was established. The data analytical study included assessing the odds ratio, concerning the presence or absence of a particular risk factor, by using binary logistic regression modeling. Probability values (p values) inferior to 0.05 were considered as representing statistically significant evidence.

Results: The performed prediction model included the following variables: mean probing depth, metal exposure, IL1B_allele2, maxillary edentulousness, and Fusobacterium nucleatum. The F. nucleatum showed significant association with the outcome. Introducing a negative coefficient appeared to prevent complications or even boost the biological defense when associated with other factors.

Conclusions: The prediction model developed in this study could serve as a basis for further improved models that would assist clinicians in the daily diagnosis and treatment planning practice of oral rehabilitation with implant overdentures.

Purpose: We examined the accuracy, including trueness and precision, of the intraoral scanners comparing with laboratory scanner to reveal the error level of intraoral scanners.

Methods: Measurements were performed using a computer numerical control coordinate measuring machine (CNCCMM) of the reference models as a control. Subsequently, intraoral scanners and a laboratory scanner were used for measurements of the reference trueness and precision of the distance were evaluated by image analyzing software.

Results: With regard to reference model, there was a significant difference between in the trueness measured by C.O.S. (COS) and that measured by the other scanners. The trueness measured by the second-generation 3M^TM true definition scanner (TDS2) and thirdgeneration 3M^TM true definition scanner (TDS3) was bigger than the one by TRIOS (TR) and KaVo (KA). With regard to reference model "B," error of the trueness measured by COS was significantly bigger, compared with the one measured by the other scanners. However, error range of intraoral scanners, except for COS, was considerably small and it should be covered with cement space.

Conclusions: The results of this study indicated that an optical impression method with an intraoral scanner could be applied to the implant therapy for multiple teeth missing.

Purpose: A 53-year-old institutionalized male patient with a history of postoperative bilateral hypoglossal nerve injury was admitted for treatment of dysphagia. He experienced dysphagia involving oral cavity-to-pharynx bolus transportation because of restricted tongue movement and was treated with a palatal augmentation prosthesis (PAP), which resulted in improved bolus transportation, pharyngeal swallowing pressure, and clearance of oral and pharyngeal residue. The mean pharyngeal swallowing pressure at tongue base with the PAP (145.5±7.5mmHg) was significantly greater than that observed immediately after removal of the PAP (118.3±10.1mmHg; p<0.05; independent t-test). Dysphagia rehabilitation with the PAP was continued. Approximately 1 month after PAP application, the patient could orally consume three meals, with the exception of foods particularly difficult to swallow.

Discussion: The supporting contact between the tongue and palate enabled by the PAP resulted in improvement of bolus transportation, which is the most important effect of a PAP. The increase in pharyngeal swallowing pressure at the tongue base because of PAPenabled tongue–palate contact might play an important role in this improvement. Since a PAP augments the volume of the palate, it enables easy contact between the tongue and palate, resulting in the formation of an anchor point for tongue movement during swallowing. Thus, application of a PAP increases the tongue force, especially that of the basal tongue.

Conclusion: A palatal augmentation prosthesis helps improve pharyngeal swallowing pressure at the basal tongue region and might contribute to the decrease of oral as well as pharyngeal residue.

Purpose: This in-vitro study tested the fracture resistance of endodontically treated molars with Mesial-Occluso-Distal (MOD) cavities restored with fibre reinforced composite material everX posterior in comparision with hybrid composite and ribbond fiber composite.

Materials and methods: Fifty intact freshly extracted human mandibular first molars were collected and were randomly divided into five groups (n=10). Group 1: positive control (PC) intact teeth without any endodontic preparation. In groups 2 through 6 after endodontic procedure standard MOD cavities were prepared and restored with their respective core materials as follows: group 2, negative control (NC) left unrestored or temporary flling was applied. Group 3, Hybrid composite (HC) as a core material (Te-Econom Plus Ivoclar Vivadent Asia) group 4, Ribbond (Ribbond; Seattle, WA, USA) +conventional composite resin (RCR) group 5, everX posterior (everX Posterior GC EUROPE) +conventional composite resin (EXP) after thermocycling fracture resistance for the samples were tested using universal testing machine. The results were analysed using ANOVA and Tukey's HSD post hoc tests.

Results: Mean fracture resistance (in Newton, N) was group 1: 1568.4±221.71N, group 2: 891.0±50.107N, group 3: 1418.3±168.71N, group 4:1716.7±199.51N and group 5: 1994.8±254.195N.

Conclusion: Among the materials tested, endodontically treated teeth restored with everX posterior fiber reinforced composite showed superior fracture resistance.

Purpose: To investigate the reinforcing efficiency and light curing properties of discontinuous S2-glass fiber-particulate reinforced resin composite and to examine length distribution of discontinuous S2-glass fibers after a mixing process into resin composite.

Methods: Experimental S2-glass fiber-particulate reinforced resin composites were prepared by mixing 10wt% of discontinuous S2-glass fibers, which had been manually cut into two different lengths (1.5 and 3.0mm), with various weight ratios of dimethacrylate based resin matrix and silaned BaAlSiO₂ filler particulates. The resin composite made with 25wt% of UDMA/SR833s resin system and 75wt% of silaned BaAlSiO₂ filler particulates was used as control composite which had similar composition as the commonly used resin composites. Flexural strength (FS), flexural modulus (FM) and work of fracture (WOF) were measured. Fractured specimens were observed by scanning electron microscopy. Double bond conversion (DC) and fiber length distribution were also studied.

Results: Reinforcement of resin composites with discontinuous S2-glass fibers can significantly increase the FS, FM and WOF of resin composites over the control. The fibers from the mixed resin composites showed great variation in final fiber length. The mean aspect ratio of experimental composites containing 62.5wt% of particulate fillers and 10wt% of 1.5 or 3.0mm cutting S2-glass fibers was 70 and 132, respectively. No difference was found in DC between resin composites containing S2-glass fibers with two different cutting lengths.

Conclusion: Discontinuous S2-glass fibers can effectively reinforce the particulate-filled resin composite and thus may be potential to manufacture resin composites for high-stress bearing application.

Purpose: The aim of the study was to evaluate functional parameters of the occlusion in complete denture wearers before and after prosthetic treatment.

Methods: The sample used as the basis for the present study consisted of 50 healthy Caucasian patients (35 women and 15 men), aged from 44 to 86 years (mean=69.18±10), with a total deficiency of teeth. All patients received new complete dentures. Each patient underwent lateral radiograph with the presence of complete dentures, both before (initially existing dentures) and after the prosthetic treatment (new restorations). Cephalometric analysis was based on the Ricketts and McNamara criteria. In order to assess the functional parameters of the occlusion T-scan III analysis was conducted. The following parameters were measured: occlusion - and disclusion time.

Results: Statistically significant differences of functional parameters obtained before and 3 months after the treatment were noted in the whole study group. Both before and after therapy occlusion time was longer in women than in men. No statistically significant link was noted between functional parameters in occlusion and age of the patients, denture wearing time, and edentulous period. Some relationships were noted between occlusion time and cephalometric parameters associated with anterior facial height.

Conclusion: Reconstruction of the surface of artificial teeth and vertical occlusal dimension affects the sustainability of parameters of occlusion and balance of forces in centric occlusion. The progressive shortening of occlusion time during the period of monitoring may be considered as a sign of progressive adaptation.