Multicenter study on visual color difference thresholds. A secondary analysis of light, medium, and dark tooth-colored specimens.

PURPOSE: This secondary analysis further analyzed variations in the 50:50% perceptibility and acceptability thresholds (PT and AT, respectively) pertaining to light, medium, and dark tooth-colored specimen sets. METHODS: Primary raw data from the original study was retrieved. Visual thresholds (Perceptibility - PT and Acceptability - AT) were analyzed among the three specimen sets - light, medium, and dark. The Wilcoxon signed-rank test was used for paired specimens, and the Wilcoxon rank-sum nonparametric test was used for independent specimens (α= 0.001). RESULTS: The 50:50% CIEDE2000 PT and AT values were significantly higher for the light-colored specimen set when compared with the medium and dark-colored specimens: 1.2, 0.7, 0.6, respectively (PT) and 2.2, 16, 14 (AT), respectively (P< 0.001). Independent of the observer group, the highest PT and AT values were always found for the light-colored specimen sets (P< 0.001). Dental laboratory technicians had the lowest visual thresholds, but not significantly different from the other observer groups studied (P> 0.001). Similarly, all research sites had statistically higher visual thresholds for the light-colored specimen set than for the medium- or dark-colored sets, except for two sites that showed statistically similar results for medium-colored specimens but were significantly different from the dark-colored set. Among the different research sites, sites 2 and 5 registered significantly higher PT thresholds for the light specimens (1.5 and 1.6, respectively), and site number 1 had a significantly higher AT threshold relative to the other sites. The 50:50% perceptibility and acceptability thresholds were significantly different among light-, medium-, and dark-colored specimens for different research sites and observer groups. CLINICAL SIGNIFICANCE: The visual perception of color difference related to light-, medium-, and dark-colored specimens varied based on observer group and their geographic location. Therefore, a greater understanding of factors that affect visual thresholds, with the observers being "the most forgiving" for color differences among the light shades, will allow diverse clinicians to overcome some of the challenges of clinical color matching.

The Effectiveness of a Shade-Matching Training Program on the Dentists' Ability to Match Teeth Color.

AIM OF THE STUDY: To study the effectiveness of a structured shade-match training program on dentists' ability to match teeth colors. METHODS: Forty dentists were selected by convenient sampling with normal color vision. The training program is based on visual attention concept and was divided into two parts (educational and training module). Level of knowledge of color was assessed pre and post using a questionnaire. Shade-matching ability was assessed pre and post by using four tabs of the VITA Linearguide 3D-MASTER shade guide (4R1.5, 5M1, 2L.15, 3L1.5). Statistical analysis used pair t test, Wilcoxon test. RESULTS: About 52.5% (n = 21) were female and 47.5% (n = 19) were male. The subjects were advanced general practitioners/GP and restorative dentists (40%, n = 16), and prosthodontists (20%, n = 8). The mean level of knowledge pre and post the training program showed a statistically significant difference (p ≤ 0.05). Shade-match ability was significant in the mean value between pre-test and post-test (p ≤ 0.05). The mean of ΔE for the shade-matching tabs was highest in 5M1 Tab (3.55 ± 2.91) followed by 4R1.5 (2.00 ± 1.30) and 2L1.5 (1.55 ± 1.40). The least ΔE was in 3L1.5 (1.54 ± 1.45). CONCLUSION: The training program that is based on visual attention was effective. The training program has increased self-assessment level of knowledge for all subjects and improved the final shade-matching performance. CLINICAL SIGNIFICANCE: Visual shade matching is currently the most frequently applied clinical method for shade matching. Assessing colors and matching shades are vital steps in aesthetic dentistry. In the absence of knowledge, shade-matching skills cannot be mastered effectively. Clinicians can improve their ability to differentiate colors through a short training regimen. Being aware of the whole process of assessing color and the factors affecting shade-matching practice will lead to a significant improvement in the ability to match dental shades. (J Esthet Restor Dent 29:E33-E43, 2017).

The Effect of Color Training of Dental Students' on Dental Shades Matching Quality.

OBJECTIVE: To assess the effect of color training on the dental shade matching quality of dental students of both gender and to study the need to include lectures and exercises about shade selection in the undergraduate dental curriculum. MATERIALS AND METHODS: One hundred and twenty junior dental students from the College of Dentistry at King Saud University participated in the present study and were distributed randomly into four testing groups. They were asked to match the color of four target shade tabs from the VITA Linearguide 3D-MASTER. Group 1 attended a brief lecture and a training exercise about dental shade matching, Group 2 only attended the lecture, and Group 3 only performed the training exercise. Group 4 did not participate in the lecture or the training exercise and served as a control. Exact matching rates were calculated and analyzed to determine the pre- and post-test matching values. Three way repeated measures analysis of variance, paired t test, and independent t-test were used to compare shade matching quality, with a significance level of p < 0.05. RESULTS: There was a significant difference between the pre- and post-test values for the students' dental shade matching qualities for all of the test groups. CONCLUSION: The effectiveness of the dental shade matching training about color and dental shade matching for improving the students' shade matching quality was proven for both genders. CLINICAL SIGNIFICANCE: Training can improve shade matching quality of dental students. (J Esthet Restor Dent 29:346-351, 2017).

Color difference thresholds in dentistry.

PURPOSE: The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. MATERIALS AND METHODS: The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site ×7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. RESULTS: The CIELAB 50:50% PT was ΔEab = 1.2, whereas 50:50% AT was ΔEab = 2.7. Corresponding CIEDE2000 (ΔE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. CONCLUSION: A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas ΔE00 /ΔEab . Observer groups and sites showed high level of statistical difference in all thresholds. CLINICAL SIGNIFICANCE: Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and interpret visual and instrumental findings in clinical dentistry, dental research, and subsequent standardization. The importance of quality control in dentistry is reinforced by increased esthetic demands of patients and dental professionals.

Long-term outcome of one-piece implants. Part II: Prosthetic outcomes. A systematic literature review with meta-analysis.

PURPOSE: To evaluate the long-term clinical performance of prosthetic reconstructions on one-piece implants, with a focus on technical and biological complications. MATERIALS AND METHODS: An electronic MEDLINE search complemented by a manual search was conducted to identify randomized and prospective controlled clinical trials on one-piece implants. Additional inclusion criteria were a mean follow-up period of at least 5 years and an inception cohort where more than 80% of the enrolled patients remained in the study at the 5- or 10-year observation point. RESULTS: Sixty-six studies from an initial yield of 597 titles were selected, and the data were extracted. Of the full-text articles examined, 46 were excluded and a total of 20 articles were finally selected. All studies were published between 1995 and 2011. Two different study designs were identified: 4 randomized controlled trials and 16 prospective cohort studies. The studies were analyzed and classified according to study type, patient characteristics, prosthetic characteristics, and biologic and technical complications after 5 and 10 years. The meta-analysis of the included studies showed a prosthetic survival rate for one-piece, one-part implants of 82.81% after 5 years and 97.85% and 98.24% in two-part implants after 5 and 10 years, respectively. Although the prosthetic survival rates were high, complications were frequent: complications of the suprastructure (18.44% to 18.75%), screw loosening/fracture (7.64%), soft-tissue complications (4.69% to 8.25%), sensory disturbances (0.36% to 6.25%), implant loss before loading (0% to 0.23%) and during function (1.10% to 3.21%), and implant fracture (0.0004%). CONCLUSION: Within the limits of this systematic review, it can be concluded that despite high long-term prosthetic survival rates, technical and biologic complications are frequent in one-piece implants, both in one-part and two-part designs. Further randomized clinical trials are needed to provide more information about the outcome of different variables associated with this type of implant design.

Volumetric measurements of removed tooth structure associated with various preparation designs.

The amount of tooth structure that is removed as a consequence of tooth preparation has rarely been quantified. The aim of this study was to quantify the volume of reduction of tooth structure associated with different commonly used preparation designs. Eighty extracted teeth were divided into eight groups according to the type of preparation design and tooth type. Each specimen underwent pre- and post preparation scanning using microcomputed tomography. The volume of the resultant tooth structure removed was analyzed. Significant differences in the amount of tooth structure removal were noted between types of coverage and types of teeth.

Long-term outcome of one-piece implants. Part I: implant characteristics and loading protocols. A systematic literature review with meta-analysis.

PURPOSE: The aim of this systematic review was to evaluate the long-term clinical performance of one-piece implants. MATERIALS AND METHODS: An electronic MEDLINE search complemented by a manual search was conducted to identify randomized and prospective cohort studies on one-piece implants. Additional inclusion criteria were: a mean follow-up period of at least 5 years and an inception cohort where more than 80% of the enrolled patients remained in the study at the 5- or 10-year observation point. RESULTS: Sixty-six studies from an initial yield of 597 titles were selected, and the data were extracted. Of the full-text articles examined, 46 were excluded from the final analysis. A total of 20 articles were finally selected. All studies were published between 1995 and 2011. Two different study designs were included: 4 randomized controlled trials and 16 prospective cohort studies. The studies were analyzed and classified according to the follow-up period, the type of implant surface, the type of edentulism, the type of loading protocol, and the type of setting. The meta-analysis of the included studies showed an implant survival rate for one-piece, one-part implants of 96.79% (95% CI: 94.04% to 98.71%) after 5 years. In one-piece, two-part implants, the survival rate was slightly higher: 98.16% (95% CI: 96.48% to 99.31%) after 5 years and 96.83% (95% CI: 93.12% to 99.24%) after 10 years. CONCLUSION: Within the limits of this systematic review, it can be concluded that high long-term survival rates can be observed with one-piece implants. Further randomized clinical trials are needed to provide more information about the outcome of different variables associated with one-piece implants.

Evaluation of self shade matching ability of dental students using visual and instrumental means.

OBJECTIVES: The purpose of this study was to evaluate the ability of dental students to match the shade of their own teeth. METHODS: Fifty female dental students in the College of Dentistry at King Saud University, who had not received any formal dental training in color science or shade matching procedures, were screened for color deficiencies and selected to participate in the study. Each subject and three clinicians selected independently the closest match for the subjects' own right or left sound maxillary central incisors under controlled viewing conditions, using VITA classical shade guide (VITA Zahnfabrik GmbH, Bad Säckingen, Germany). Each examined central incisor and the 16 samples of VITA classical shade guide were measured with the VITA Easy Shade (VES) spectrophotometer to determine the CIELAB color parameters. The color differences (ΔE) between each examined tooth and the 16 samples of the shade guide were calculated. The minimum ΔE values were compared to ΔE values of the shade obtained by VES, subjects and clinicians. RESULTS: The results showed a significant difference in the accuracy of shade selection between the instrumental and visual means. ΔE value of shade selected by clinicians was significantly lower than those selected by the subjects. CONCLUSIONS: It was concluded that, spectrophotometric shade analysis was more accurate compared to human shade assessment. CLINICAL SIGNIFICANCE: A reliable self-perception of the subjects' own tooth color, may aid in the shade matching procedures. It might lead to increased patients' satisfaction at the finalization of the restorative procedures.

Evaluation of color duplication in metal-ceramic complexes using visual and instrumental shade-matching systems.

This study was designed to evaluate color differences (DE) between intended and fabricated shades of various metal-ceramic complexes using visual and instrumental shade determination. Forty-two master disks were made to represent every tab in two shade guides. The shades of the master disks were determined visually and instrumentally. Accordingly, 84 experimental disks were fabricated. Color measurements of the master and fabricated disks were performed using a spectrophotometer. Visual shade determination showed a significantly lower DE value than the instrumental shade determination. However, all groups showed DE values exceeding 2.75, which could be considered perceivable and therefore clinically unacceptable. A reliable shade duplication of an existing metal-ceramic restoration cannot be ensured, regardless of the method of shade assessment.

Consistency in color parameters of a commonly used shade guide.

OBJECTIVE: The use of shade guides to assess the color of natural teeth subjectively remains one of the most common means for dental shade assessment. Any variation in the color parameters of the different shade guides may lead to significant clinical implications. Particularly, since the communication between the clinic and the dental laboratory is based on using the shade guide designation. The purpose of this study was to investigate the consistency of the L∗a∗b∗ color parameters of a sample of a commonly used shade guide. MATERIALS AND METHODS: The color parameters of a total of 100 VITAPAN Classical Vacuum shade guide (VITA Zahnfabrik, Bad Säckingen, Germany(were measured using a X-Rite ColorEye 7000A Spectrophotometer (Grand Rapids, Michigan, USA). Each shade guide consists of 16 tabs with different designations. Each shade tab was measured five times and the average values were calculated. RESULTS: The ΔE between the average L∗a∗b∗ value for each shade tab and the average of the 100 shade tabs of the same designation was calculated. Using the Student t-test analysis, no significant differences were found among the measured sample. CONCLUSION: There is a high consistency level in terms of color parameters of the measured VITAPAN Classical Vacuum shade guide sample tested.

Effect of surface treatment on the micro-shear bond strength to zirconia.

UNLABELLED: The constant quest for finding the ultimate esthetic dental restorative material has led to numerous alternatives. These materials, in addition to possessing optical properties simulating natural teeth, should also have physical properties that can withstand the harsh oral environment. Due to their greater toughness, zirconium oxide materials have been used as a core material for all-ceramic restorations. OBJECTIVE: The objective of this study was to evaluate the resin-composite micro-shear bond strength to zirconia using different techniques of surface treatment. MATERIALS AND METHODS: Fully sintered zirconia (LAVA, 3M-ESPE, Seefeld, Germany) discs were used in combination with resin-composite (Filtek Supreme, 3M-ESPE, Seefeld, Germany) discs and divided into four groups of surface treatments. The micro-shear bond strength was measured by applying an axial load on the bonded interface until failure occurred. Failure load (N) was determined and the samples were examined under a SEM and the failure type was identified. One-way analysis of variance (ANOVA) was used to analyze the data with the level of significance α = 0.05. RESULTS: Data analysis revealed significant difference between the different tested surface treatments with the group using sandblasting and coated with an experimental primer showing the highest failure load and a cohesive fracture pattern. CONCLUSION: Within the limitations of this in vitro study the use of an experimental primer achieved a better bond strength in combination with air-abrasion particles.

Fracture resistance and failure location of zirconium and metallic implant abutments.

AIM: The purpose of this study was to evaluate the fracture resistance and failure location of single-tooth, implant-supported, all-ceramic restorations on different implant abutments subjected to a maximum load. METHODS AND MATERIALS: Forty Certain 3i implants and 20 ITI Straumann implants were used in this study in combination with 20 UCLA abutments, 20 ZiReal abutments, and 20 synOcta Ceramic Blanks to form three groups according to abutment type. All 60 abutments were prepared with standard measurements: a 1.0 mm deep chamfer, 2.0 mm of incisal reduction, and a total height of 7 mm. Sixty IPS Empress 2 full ceramic crowns were fabricated and cemented on each abutment with a resin cement. Static loading was simulated under maximum loading and fracture locations were noted. RESULTS: The mean load to failure data and standard deviations for the three groups were as follows: Group 1 (792.7 N +/- 122.5) and Group 3 (793.6 +/- 162.3) showed no significant difference in fracture resistance while the values for specimens in Group 2 (604 N +/- 191.1) had the lowest mean value and were significantly lower. In Group 1, 16 crowns and four abutment fractures were reported, while in Group 3, 17 crowns and three abutments fractured. Group 2 actually showed three types of fractures. Two specimen fractures were located at the implant level, six with fractures occuring within the Empress 2 all-ceramic crown, and the remaining 12 failures were located at the abutment level. CONCLUSION: Within the limitations of this laboratory study, the following conclusions were drawn: The mean load-to-failure values for all three groups were well above the reported normal maximal incisal load range. The load to failure for both the zirconium oxide (ZrO2) abutments (ZiReal on 3i Certain implants and synOcta Ceramic Blanks on SLA ITI Straumann implants) had mean fracture loads of 792.7 N (+122.6) and 604.2 N (+191.2), respectively. The zirconium oxide (ZrO2) ZiReal and titanium (UCLA) abutments on the 3i Certain implants had statistically significantly higher fracture loads (792.7 N and 703.7 N, respectively) than those recorded for the 3i Ceramic Blank abutments on the SLA ITI Straumann implant (604.2 N). The ITI Straumann Ceramic Blank abutments showed uniform fracture behavior. Fracture mainly emanated from the cervical buccal aspect of the abutment. CLINICAL SIGNIFICANCE: The three abutments tested showed they can withstand clinical loads above the normal range of mastication.

Arthroscopy vs. open-joint surgery for the management of internal derangement of the temporomandibular joint: a retrospective study comparing female subjects from two centers.

AIM: The aim of this retrospective study was to assess the treatment outcome of arthroscopy and open-joint surgery in the management of internal derangement of the temporomandibular joint (TMJ). BACKGROUND: Apart from pain being the major complaint in patients with temporomandibular joint disorders (TMDs), a variety of function-related symptoms are reported including joint noises, locking, limited movement, and alterations in occlusion. Surgical management procedures of internal derangement of the TMJ vary widely at present. The criteria for the assessment of successful outcome of the treatment are also variable. METHODS AND MATERIALS: The retrospective study was carried out at two centers in Paris and Beirut. Sixty-two female patients with an age range of 35.1 years (28 had arthroscopy and 34 had open surgery) were included in the study. The patients were followed-up for 12 months. A standardized questionnaire and visual analogue scale (VAS) was developed and used for the assessment of pain and mandibular range of motion. A chi-square test was used to observe the significance of difference among both groups. CONCLUSION: Within the limitations of this study, it was concluded arthroscopic surgery appeared to be safe with pain reduction and increased mandibular range of motion for 80% of the patients. Further research is needed on a larger prospective sample to assess the comparison of both techniques in terms of enhanced quality of life among the study population. CLINICAL SIGNIFICANCE: Arthroscopic surgery appears to be a safe, minimally invasive, and effective method for treating internal derangements of the TMJ.

Effect of different all-ceramic crown system on fracture resistance and failure pattern of endodontically treated maxillary premolars restored with and without glass fiber posts.

Endodontically treated teeth are traditionally restored with a crown to prevent fracture. The aim of this study was to compare the fracture resistance and failure modes of endodontically treated maxillary premolars treated with or without a fiber post and restored with different types of crowns. Eighty human maxillary premolars were selected. After root canal treatment, the teeth were embedded in resin blocks and divided into four groups. Samples received MOD cavity preparations and were divided into two subgroups: with and without fiber posts and restored using porcelain fused to metal, lithium disilicate, fiber-reinforced composite, or zirconia crowns. The specimens were vertically loaded in the central fossa using a universal loading machine until failure, and the maximum breaking loads were recorded. Samples were perfused with Indian ink to highlight the fracture lines and the mode of failure that was classified as restorable or nonrestorable. Even without post, all crown designs resisted vertically applied forces beyond those that may be encountered in the mouth. Two-way analysis of variance revealed the use of a fiber post (p = 0.007) and the type of crown (p < 0.001) significantly affected the restorability of fractured teeth. The relationship between placing or not placing the post and the type of failure (restorable/nonrestorable) was found to be significant (chi(2) test, p = 0.002). Although post placement resulted in higher fracture resistance values, these were significant for Empress II crowns only. The results suggest that the posts could contribute to the reinforcement and strengthening of pulpless maxillary premolars. With respect to failure modes, placement of fiber posts improved the fracture from nonrestorable to restorable patterns. This study suggests that the placement of fiber posts is necessary to improve fracture resistance even under full-coverage crowns.

Fracture resistance and failure patterns of endodontically treated mandibular molars restored using resin composite with or without translucent glass fiber posts.

The elastic modulus of the restorative material is important in restoring endodontically treated teeth. This study aimed to compare the fracture resistance and failure patterns of 90 mandibular molars restored using resin composites with or without fiber posts, with respect to the number of residual cavity walls. Five restoration types were performed corresponding to different wall defects (groups 1-5). Groups were divided in two subgroups corresponding to the use or absence of fiber posts. Teeth were loaded and resistance of specimens was measured as the axial compressive load to cause fracture and macroscopic fracture patterns were observed. One way ANOVA revealed a significant difference in fracture resistance (p < 0.001). Tukey post hoc test also revealed significant differences between groups as samples restored with fiber posts exhibited mostly restorable fractures. It was concluded that the resistance of endodontically treated mandibular molars restored with composite resins is mainly affected by the number of residual walls. Using fiber-reinforced posts optimized fracture patterns.

Adhesion between prefabricated fiber-reinforced posts and different composite resin cores: a microtensile bond strength evaluation.

PURPOSE: The aim of this study was to evaluate the bond strengths between various resin composites used as core materials (Multicore Flow, Ivoclar-Vivadent; Tetric Flow, Ivoclar-Vivadent; Filtek Flow, 3M-ESPE; Tetric Ceram, Ivoclar-Vivadent; Filtek Z250, 3M-ESPE), and an FRC post (FRC Postec Plus, Ivoclar-Vivadent) by means of the microtensile nontrimming technique. MATERIALS AND METHODS: Five experimental groups were used. For the microtensile nontrimming technique, 45 to 50 beam-shaped specimens per group were obtained from cylinders of core material, which had been built up around the post by progressively adding small increments of composite resin. Each specimen was loaded in tension until failure at either one of the two post/core interfaces present in each stick. The differences in interfacial bond strength amongthe groups were tested for statistical significance with the one-way ANOVA test, followed by the Dunnett test for post-hoc comparisons. RESULTS: The measured bond strengths in MPa were 17.29 +/- 6.02 for FRC+MultiCore Flow, 16.37 +/- 6.92 for FRC+Tetric Flow, 13.14 +/- 5.35 for FRC + Filtek Flow, 12.38 +/- 4.34 for FRC + Tetric Ceram, and 10.75 +/- 5.43 for FRC + Filtek Z250. The statistical analysis revealed that MultiCore Flow achieved significantly higher bond strengths than Filtek Flow (p = 0.03), Tetric Ceram (p < 0.001), and Filtek Z250 (p < 0.001). The bond strength of Tetric Flow was significantly higher than that of Filtek Z250 (p = 0.003). CONCLUSION: For core buildup on a fiber post, dual-cure composites appear to be preferable to light-curing composites.

Sentiments expressed in relation to tooth loss: a qualitative study among edentulous Saudis.

PURPOSE: The objective was to explore and gain insight into the sentiments surrounding tooth loss in a group of edentulous Saudis. MATERIALS AND METHODS: Using a qualitative methodology, 44 edentulous patients who were receiving complete denture treatment were interviewed in private, in the Arabic language. Interviews were tape recorded and semistructured, following a list of predetermined and piloted topics, but dialogue also took place, with the freedom for both interviewer and interviewee to explore areas of interest. All recordings were transcribed, translated into English, and interpreted independently by two members of the team to identify the core themes associated with tooth loss. RESULTS: The mean age of participants was 58.9 years (range 35 to 72 years), and they had been edentulous for a mean of 7.1 years (range 3 months to 22 years). The main themes related to tooth loss were unqualified acceptance, inevitability with old age, behavior changes with respect to eating comfort, aged appearance, self-responsibility, positively perceived benefits, high prosthetic expectations and reduced level of denture satisfaction, and some need for privacy. CONCLUSION: The lack of any outward indication that participants experienced bereavement suggests that outlook on life can influence the impact of tooth loss. Participants' unqualified acceptance of their edentulous fate, yet their clear need to "normalize" oral function, reflects a degree of pragmatism toward life events. The strong influence of religion in Saudi society is a possible factor in the sentiments expressed.