Interdisciplinary all-on-four® concept for mandibular jaw in dental education - do students benefit from individual 3d printed models from real patient cases?

PURPOSE: Digitalization is assuming increasing significance in dental education, as dental students are increasingly exposed to digital implant planning and contemporary technologies such as 3D printing. In this study, we present a cohort analysis aimed at assessing the potential benefits derived from the utilization of 3D prints to seamlessly translate planned procedures into real-life applications. METHODS: 21 dental students participated in a virtual planning and hands-on course across two cohorts (C1: n = 10, C2: n = 11). The virtual implant planning phase involved the placement of four implants on an atrophic lower jaw model. Subsequently, Cohort 1 (C1) executed the implantation procedure on a prefabricated hands-on model, while Cohort 2 (C2) engaged with 3D prints representing their individual implant planning during the hands-on session. Subjective assessments of knowledge, skills, and the perceived utility of 3D prints were conducted through pre- and post-course questionnaires, utilizing a 5-point scale. RESULTS: In the subjective evaluation, 17 out of 21 participants expressed a positive appraisal of the use of personalized models. Notably, there was no statistically significant improvement in overall knowledge scores; however, there was a discernible increase of 0.5 points in the ratings related to perceived expertise and procedural abilities. CONCLUSION: While there was a notable increase in the subjective ratings of knowledge and abilities, no statistically significant difference was observed between the two groups. The consensus among dental students is that individually planned and printed implant models serve as a valuable and effective tool in hands-on courses.

Retentive Strength of CAD/CAM-Fabricated All-Ceramic Crowns Luted on Titanium Implant Abutments Using Different Ceramic Materials and Luting Agents: An In Vitro Study.

Objectives: This study aimed to determine the retentive strength of monolithic hybrid-all-ceramic crowns luted on titanium implant abutments. Material and Methods: In total, 450 crowns (75 each of Mark II, Empress CAD, e.max CAD, Suprinity, Enamic, Celtra Duo) were milled using a CAD/CAM system. The crowns were cemented onto sandblasted titanium implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, Fujicem, and Panavia 2.0). After thermocycling was performed (5000 cycles: 5−55 °C, 30-s dwell time), the crowns were removed using a universal testing machine. The location of luting-agent residue on the abutment and inner crown surfaces was evaluated. Analyses of variance (ANOVA) with the Bonferroni correction were performed to evaluate differences of retentive strength depending on the crown material and the kind of the luting agent. Results: The retentive strengths for the different ceramic materials were Vita Mark II: 652N-759N (SD:134N-146N), Empress CAD: 681N-822N (SD: 89N-146N), e.max CAD: 784N-1044N (SD: 109N-176N), Vita Enamic: 716N-1177N (SD: 132N-220N), Vita Suprinity: 867N-1488N (SD: 202N-278N), and Celtra Duo 772N-1335N (SD:151N-229N). After the removal trials, the visual documentation showed different adhesive residue location depending on the ceramic materials. Furthermore, the pull-off force was dependent on the choice of adhesives. No significant differences were found between different luting agents and the ceramic material Vita Mark II and Empress CAD. EmaxCAD showed significant differences with Unicem and FujiCem compared to Panavia, as did VitaSuprinity, VitaEnamic, and Celtra Duo (p < 0.001). Conclusions: The ceramic material used seems to influence the retentive strength and the use of certain luting agents results in a higher retentive strength for some ceramic materials.

Marginal and Internal Precision of Zirconia Four-Unit Fixed Partial Denture Frameworks Produced Using Four Milling Systems.

BACKGROUND: CAD/CAM systems enable the production of fixed partial dentures with small and reproducible internal and marginal gaps. PURPOSE: The purpose of this study was to evaluate the reproducibility of the marginal and internal adaptations of four-unit fixed partial denture frameworks produced using four CAD/CAM systems. MATERIALS AND METHODS: Prepared dies of a master model that simulated the loss of the first left molar were measured. Fifteen frameworks were manufactured using four CAD/CAM systems (A-D). The internal fit was determined by the replica technique, and the marginal gap was determined by microscopy. ANOVA was carried out to detect significant differences, and the Bonferroni adjustment was performed. The global level of significance was set at 5%. RESULTS: The mean gap size ranged from 84 to 132 µm (SD 43-71 µm). The CAD/CAM systems showed significant variance (p < 0.001), and system A (VHF) showed the smallest gaps. The smallest gaps for each system were in the molar part and in the marginal region of the frameworks (p < 0.001). CONCLUSIONS: The CAD/CAM systems showed significantly different gap sizes, particularly between premolars and molars and among the marginal, axial and occlusal regions. All of the systems are suitable for clinical application.

The reproducibility of electronic color measurements of the marginal gingiva.

INTRODUCTION: This study evaluated the reproducibility of electronic color determination system evaluations of the marginal gingiva, which could be important for adhesive cervical fillings or prosthetic restorations that imitate the gingiva. MATERIAL AND METHODS: In 50 subjects, the L*, a*, and b* color coordinates were evaluated five times at a point in the marginal area of a central incisor using different electronic color determination systems: (SP) Shadepilot, (ES) Easyshade, (CE) Crystaleye, and (SV) X-Rite. The mean color difference (ΔE) and its standard deviation between the five measurements from each participant were calculated separately for each device. Further ICC for interdevice reliability was determined. RESULTS: The L*, a*, and b* color coordinates and ΔE values differed significantly among the systems (p < 0.001). Within each patient and measurement system, ΔE ranged from 1.4 to 3.2 (SD 1.1-2.5), L* from 2.6 to 5.7 (SD 2.6-5.7), a* from 11.9 to 21.3 (SD 3.6-3.9), and b* from 15.1 to 28.9 (SD 1.7-4.3). Interdevice reliability ranged between 0.675 and 0.807. CONCLUSIONS: Color determination of the marginal gingiva using the electronic tooth color determination systems tested herein showed limited reproducibility. The results obtained with the different measurement systems differed enormously. CLINICAL RELEVANCE: These results show that the electronic color measurement devices tested allow no high reproducible determination of color coordinates of the marginal gingiva.

Effects of ceramic layer thickness, cement color, and abutment tooth color on color reproduction of feldspathic veneers.

AIM: To optimize the esthetics of ceramic restorations, it is important to determine accurately the effects of various parameters on the final color of the restoration. However, there is a lack of information on what determines the color of translucent feldspathic veneers formed using ceramics such as Vita Mark II. The aim of this study was to evaluate the effects of the ceramic layer thickness, cement color, and abutment tooth color on the color of the feldspathic ceramic veneer restoration. MATERIAL AND METHODS: A total of 30 all-ceramic monolithic veneers (Vita Mark II) were fabricated using a CAD/CAM system. The crowns were divided into three groups of differing ceramic thickness (0.4-, 0.7-, and 1.0-mm thick). Each type of crown was seated on six different-colored abutment teeth (1M1 [reference], 1M2, 2M2, 3M2, 4M2, and 5M2) using seven different try-in paste colors. The color of the resulting restoration was evaluated using spectrophotometry with a spot-measurement device (Vita Easyshade Advance 4.0). Color data are expressed in CIE L*a*b* system coordinates, and color differences ΔE relative to the reference tooth were calculated and analyzed using one-way analysis of variance (ANOVA) with the Bonferroni post hoc test at α = 0.05. RESULTS: The color difference ΔE of the feldspathic all-ceramic veneer system was significantly affected by the thickness of the ceramic layer, the cement color, and the abutment tooth color (P < 0.05). The smallest values of ΔE compared with the reference color were found when try-in pastes shade -3 was used. As the thickness of the ceramic layer increased, a significant decrease in ΔE was found. As the color of the abutment tooth varied from light to dark, a significant increase was found in ΔE. CONCLUSION: The thickness of the ceramic layer, the cement color, and the abutment tooth color significantly affected the color of the resulting CAD/CAM feldspathic ceramic veneer restoration.

The Randomized Shortened Dental Arch Study: Tooth Loss Over 10 Years.

PURPOSE: This study aimed to compare the long-term outcomes of two different nonimplant treatments in the bilateral shortened dental arch (SDA). MATERIALS AND METHODS: In a multicenter randomized controlled clinical trial, patients with complete molar loss in one arch were assigned to one of two different nonimplant treatments. In the partial removable dental prosthesis (PRDP) group, patients were provided with a distal-extension prosthesis retained with precision attachments. In the SDA group, patients were treated according to the SDA concept by preserving or restoring a premolar occlusion. RESULTS: Of the 152 treated patients, 82 reached the 10-year examination independent of their dental or prosthetic status. In the intention-to-treat analysis, the survival rates for tooth loss at 10 years were 0.44 (95% confidence interval [CI]: 0.30 to 0.56) in the PRDP group and 0.52 (95% CI: 0.37 to 0.65) in the SDA group. For tooth loss in the study arch, the survival rates were 0.67 (95% CI: 0.52 to 0.78) in the PRDP group and 0.60 (95% CI: 0.45 to 0.73) in the SDA group. The number of teeth lost was higher than expected. In a multivariate analysis using a multiple Cox regression model, the covariates age (unit: 1 year, Hazard Ratio [HR]: 1.033, P = .03) and DMFT value (unit: 1 tooth, HR: 1.121, P = .03) were significant for time to first tooth loss in the study arch. CONCLUSION: The results suggest an overestimation of the influence of the prosthetic management of the bilateral SDA. In treatment decisions, patient preferences should be considered with appropriate weight.

Comparison of visual shade matching and electronic color measurement device.

OBJECTIVE: The objective of this study was to compare the performance of visual shade matching and spectrophotometric measurements. MATERIALS AND METHODS: A total of 100 observers matched pairs of corresponding shade tabs from two VITA classical A1-D4 shade guides. The tab identifiers on one shade guide were masked. Lack of visible color differences between the corresponding tabs was confirmed by means of an intraoral spectrophotometer. Means and standard deviations were calculated. Analysis of variance (ANOVA) (α = 0.05) with a Bonferroni correction was performed to detect significance of differences between groups. RESULTS: A total of 72.5% of tab pairs (or 11.6 tabs) were matched using the visual method, and 98.9% were matched using the spectrophotometer (P < 0.001). Female observers showed significantly better results than male observers (P = 0.027). Both genders showed the highest visual scores in group B, followed by groups C, A, and D. CONCLUSIONS: Instrumental shade-matching systems have the potential to improve color matching in dentistry. Results were influenced by gender. CLINICAL RELEVANCE: The dental spectrophotometer exhibited a significantly higher percentage of correct matches of corresponding shade tabs compared with conventional visual shade matching.

Reliability of visual and instrumental color matching.

OBJECTIVE: The aim of this investigation was to evaluate intra-rater and inter-rater reliability of visual and instrumental shade matching. MATERIALS AND METHODS: Forty individuals with normal color perception participated in this study. The right maxillary central incisor of a teaching model was prepared and restored with 10 feldspathic all-ceramic crowns of different shades. A shade matching session consisted of the observer (rater) visually selecting the best match by using VITA classical A1-D4 (VC) and VITA Toothguide 3D Master (3D) shade guides and the VITA Easyshade Advance intraoral spectrophotometer (ES) to obtain both VC and 3D matches. Three shade matching sessions were held with 4 to 6 weeks between sessions. Intra-rater reliability was assessed based on the percentage of agreement for the three sessions for the same observer, whereas the inter-rater reliability was calculated as mean percentage of agreement between different observers. The Fleiss' Kappa statistical analysis was used to evaluate visual inter-rater reliability. RESULTS: The mean intra-rater reliability for the visual shade selection was 64(11) for VC and 48(10) for 3D. The corresponding ES values were 96(4) for both VC and 3D. The percentages of observers who matched the same shade with VC and 3D were 55(10) and 43(12), respectively, while corresponding ES values were 88(8) for VC and 92(4) for 3D. CONCLUSIONS: The results for visual shade matching exhibited a high to moderate level of inconsistency for both intra-rater and inter-rater comparisons. The VITA Easyshade Advance intraoral spectrophotometer exhibited significantly better reliability compared with visual shade selection. CLINICAL SIGNIFICANCE: This study evaluates the ability of observers to consistently match the same shade visually and with a dental spectrophotometer in different sessions. The intra-rater and inter-rater reliability (agreement of repeated shade matching) of visual and instrumental tooth color matching strongly suggest the use of color matching instruments as a supplementary tool in everyday dental practice to enhance the esthetic outcome.

The randomized shortened dental arch study: influence of two different treatments on interdental spacing over 5 years.

OBJECTIVES: Being a secondary outcome in a multicenter randomized controlled trial, the present analysis focused on interdental spacing in the shortened dental arch (SDA). The aim was to evaluate changes in interdental spacing in dependence of two different treatments after an observation period of up to 5 years. MATERIAL AND METHODS: Patients were either treated with a partial removable dental prosthesis (PRDP) for molar replacement (PRDP group) or according to the SDA concept aiming at a premolar occlusion (SDA group) in a randomized manner. Interdental spacing in the anterior region was measured with gauges and categorized as "0" (<0.1 mm), "1" (<0.5 mm), "2" (0.5-1 mm), and "3" (>1 mm). The statistical analysis was performed with analysis of variance models followed by linear contrast. RESULTS: Ninety-one patients (SDA n = 41, PRDP n = 50) were included. Changes of interdental spacing were detected in 70.7 % of all cases. A significant difference between the mean score changes was found in the mandible comparing the PRDP group and the SDA group. The respective mean score changes from baseline to 5 years were 0.23 (SD 0.49) for the PRDP group and 0.02 (SD 0.30) for the SDA group (p = 0.023). CONCLUSIONS: Major interdental spacing could be observed in neither of the groups. The SDA concept resulted in a slightly better outcome. CLINICAL RELEVANCE: When deciding whether to replace missing molars, the present results give further support to the SDA concept.

Polygonal Area of Prosthesis Support with Straight and Tilted Dental Implants in Edentulous Maxillae.

PURPOSE: The aim of this in vitro study was to assess the increase in the polygonal area of implant-retained prosthesis supports in edentulous maxillae with the use of tilted distal implants compared with the use of straight distal implants, using a variety of implant lengths. MATERIALS AND METHODS: A total of 25 DICOM datasets of atrophic edentulous maxillae were provided. Bone augmentations in the molar region had to be avoided. Two straight reference implants were virtually inserted in the anterior region. Two additional implants were placed far distally on both sides (4 groups: [1] straight, 12-mm length; [2] straight, 10 mm; [3] straight, 8 mm; [4] tilted, 12-16 mm). The resulting implant-supported polygon was measured for each of the 4 groups using three-dimensional planning software. RESULTS: The mean sagittal depth of the supported polygon in Group 1 was 9.9 mm (standard deviation [SD] 4.4) on the right and 10.2 mm (SD 4.4) on the left, and it was 33.7 mm (SD 5.8) in width. For Group 2, the mean sagittal depth was 11.5 mm (SD 5.0) on the right and 11.9 mm (SD 4.7) on the left, and the width was 35.2 mm (SD 5.6). The measurements for Group 3 were 13.8 mm (SD 4.9) deep on the right, 13.8 mm (SD 5.1) deep on the left, and 37.0 mm (SD 5.4) in width. For Group 4, the depth was 15.8 mm (SD 4.9) on the right and 16.4 mm (SD 5.8) on the left, and the width was 39.0 mm (SD 5.1). CONCLUSION: The area of implant-retained prosthesis support can be enlarged by the use of tilted implants (12 to 16 mm in length, 42 to 45 degrees) compared to the use of straight 8-mm implants (resulting increase: about 15%).

Fracture Strength of Monolithic All-Ceramic Crowns on Titanium Implant Abutments.

PURPOSE: The fracture strengths of all-ceramic crowns cemented on titanium implant abutments may vary depending on crown materials and luting agents. The purpose of this study was to examine differences in fracture strength among crowns cemented on implant abutments using crowns made of seven different monolithic ceramic materials and five different luting agents. MATERIALS AND METHODS: In total, 525 crowns (75 each of Vita Mark II, feldspathic ceramic [FSC]; Ivoclar Empress CAD, leucite-reinforced glass ceramic [LrGC]; Ivoclar e.max CAD, lithium disilicate [LiDS]; Vita Suprinity, presintered zirconia-reinforced lithium silicate ceramic [PSZirLS]; Vita Enamic, polymer-reinforced fine-structure feldspathic ceramic [PolyFSP], Lava Ultimate; resin nanoceramic [ResNC], Celtra Duo; fully crystallized zirconia-reinforced lithium silicate [FcZirLS]) were milled using a CAD/CAM system. The inner surfaces of the crowns were etched and silanized. Titanium implant abutments were fixed on implant analogs, and airborne-particle abrasion was used on their exterior specific adhesion surfaces (Al2O3, 50 µm). Then, the abutments were degreased and silanized. The crowns were cemented on the implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, GC FujiCEM, Panavia 2.0). After thermocycling for 5,000 cycles (5 to 55°C, 30 seconds dwell time), the crowns were subjected to fracture strength testing under static load using a universal testing machine. Statistical analyses were performed using analysis of variance (α = .0002) and the Bonferroni correction. RESULTS: No significant difference among the luting agents was found using the different all-ceramic materials. Ceramic materials LiDS, PSZirLS, PolyFSP, and ResNC showed significantly higher fracture strength values compared with FSC, FcZirLS, and LrGC. The PSZirLS especially showed significantly better results. CONCLUSION: Within the limitations of this study, fracture strength was not differentially affected by the various luting agents. However, the fracture strength was significantly higher for PSZirLS, PolyFSP, ResNC, and LiDS ceramics than for the FSP, LrGC, and the FcZirLS ceramic with all luting agents tested.

Dental color matching: A comparison between visual and instrumental methods.

The aim of this study was to compare the agreement rate (%) and color difference (ΔE*ab) of three dental color-measuring devices, with the visual shade identification. The tooth color were determined by two operators, which were advised to select a VITA classic shade tab in each other's agreement. The Shadepilot (SP), CrystalEye (CE) and ShadeVision (SV) were used to measure tooth color. Statistically analyses include agreement rate (%), color difference (ΔE*ab), McNemar test (p=0.05), Student's t-test (p=0.05) and Bland Altman scatterplots. The SP had an agreement of 56.3% with the visual shade determination, the CE 49.0% and SV 51.3%. ΔE*ab of the visually and instrumentally selected shade tabs and natural teeth were frequently above the threshold for acceptability. Comparing both methods, for SP ΔE*ab values differ in a range of clinical acceptability.

Sensitivity and Specificity of Stability Criteria for Immediately Loaded Splinted Maxillary Implants.

BACKGROUND: To assess the suitability of dental implants for immediate loading, primary stability is usually evaluated intraoperatively. PURPOSE: This retrospective study aimed to assess the suitability of three stability parameters - namely, insertion torque (IT), implant stability quotient (ISQ; measured by resonance frequency analysis), and Periotest (PT) values - as potential predictors for the risk of nonosseointegration of immediately loaded splinted implants. The stability parameters were routinely collected under immediate loading. MATERIALS AND METHODS: Nineteen patients with 11 edentulous and 8 partially edentulous maxillae were treated with 105 dental implants, which were immediately loaded using temporary fixed dentures. The IT results, PT values, and ISQ results were recorded. Receiver operating characteristic analysis was performed to assess the quality of each parameter as a diagnostic test. RESULTS: After a 3-month observation period, 11 implants in four patients were not osseointegrated. The IT and ISQ (IT 25.0 ± 12.5 Ncm and 8.4 ± 2.3 Ncm; PT -1.5 ± 3.0 and +2.7 ± 3.0; and ISQ 62.6 ± 6.7 and 54.7 ± 6.2) differed significantly between the osseointegrated and failed implants (p < .005). The IT showed the greatest specificity at a sensitivity of 1 and the greatest area under the curve (AUC; 0.929), followed by the PT value (AUC = 0.836) and ISQ (AUC = 0.811). CONCLUSIONS: Among the intraoperative parameters analyzed, IT showed the highest specificity at a high sensitivity of 1. Therefore, the IT can be considered the most valid prognostic factor for osseointegration of immediately loaded splinted dental implants.

Retentive strength of monolithic all-ceramic crowns on implant abutments.

The aim of the study was to determine the retentive strength of monolithic all-ceramic crowns cemented on titanium implant abutments. 225 crowns (75 crowns each of Mark II, Empress CAD, and e.max CAD) were milled using a CAD/ CAM system. The crowns were cemented onto sandblasted titanium implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, Fujicem, and Panavia 2.0). After thermocycling, the crowns were removed using a universal testing machine. The location of luting agent residue on the abutment and inner crown surfaces was evaluated. Statistical analysis was performed using ANOVA with the Bonferroni correction. In comparing the luting agents, no significant difference was found between Vita Mark II and Empress CAD. For e.max CAD, the luting agent RelyX Unicem had a significantly higher mean retentive strength than did Multilink Implant (p = 0.003) or Panavia 2.0 (p = 0.001). In comparing the ceramic materials, e.max CAD showed significantly higher pull-off strengths than the other two ceramic materials when the luting agents RelyX Unicem and Fujicem were used (all p < 0.001). The residues of nearly all luting agents were located entirely or almost entirely (75%-100%) on the inner crown surfaces of all ceramic materials, except for the luting agent GC Fujicem, which left more luting agent residue (0%-75%) on the abutment surfaces of all ceramic materials. In comparing the five luting agents, significant differences in the resulting retentive strength were only found for the ceramic material e.max CAD. The other ceramic materials did not show significant differences in retentive strength, independent of the luting agent.

Long-term effect of overdenture bar design on peri-implant tissues.

PURPOSE: To evaluate factors promoting mucositis and peri-implantitis (plaque accumulation, poor peri-implant soft tissue health, bone loss) with regard to prosthetic attachment systems consisting of implant-supported bar-retained overdentures. MATERIALS AND METHODS: Patients who received TiOblast implants to support overdentures retained by either (1) prefabricated bars with or without extensions or (2) cast bars were recalled and examined clinically and radiographically. Plaque Index (PI), Sulcus Bleeding Index (SBI), probing pocket depth (PPD), and peri-implant bone loss were measured. Peri-implant tissue health was assessed, and the presence of mucositis and peri-implantitis was recorded. One-way analysis of variance with the Bonferroni adjustment was used to compare groups (α = .05). RESULTS: Five to 10 years after prosthetic loading, 107 patients who received 516 TiOblast implants were evaluated; 31 of these patients were treated with 131 implants to support bar-retained overdentures. PI, SBI, PPD, and pathologic bone loss were least common in the group with prefabricated bars, followed by the group with prefabricated bars with extensions, and were most common in the group with cast bars. Plaque accumulation and pathologic bone loss values were higher with implants that supported mandibular bar-retained overdentures than with those supporting maxillary bar-retained overdentures. However, these differences among attachment systems or between maxillary and mandibular implants were not significant (P > .05). Mucositis was observed in one implant in the group with prefabricated bars, four implants in the group with prefabricated bars with extensions, and four implants in the group with cast bars. Peri-implantitis was observed in one implant of the cast bar group. CONCLUSIONS: Five to 10 years after prosthetic loading, no significant difference in PI, SBI, PPD, pathologic bone loss, or peri-implant tissue conditions among the different bar designs tested was observed.

[Orthodontic treatment of patients medicated with bisphosphonates-a clinical case report].

INTRODUCTION: Bisphosphonates (BP) are an established medication, e.g., for the prevention/therapy of osteoporosis. The effects of the changed bone metabolism for orthodontic treatments are unknown. CASE REPORT: A 66-year-old woman underwent a total oral rehabilitation. The therapy included (1) tooth extractions, (2) periodontal treatment, (3) insertion of dental implants, (4) provisional implant restorations, (5) orthodontic treatment, and (6) definite implant restorations. The orthodontic tooth movements were in- and retrusion of the upper frontal teeth, intrusion of the lower front teeth, using the dental implants as skeletal anchorage. After implant insertion and one month before beginning the orthodontic treatment, osteoporosis was diagnosed in this patient and, without notification to our facility, BP treatment was initiated by her general practitioner (alendronate oral, 70 mg/week), with an overall duration of intake of 7 months. After 13 months, the orthodontic treatment was successfully accomplished; however enlarged periodontal gaps, sclerotic bone areas, and mild apical root resorptions of the upper frontal teeth were found in this patient. CONCLUSION: Currently, there are no recommendations for orthodontic patients undergoing BP therapy. Orthodontic tooth movement in this low-risk patient with a short duration of intake and a low-dose BP medication was possible. Because of the reduced bone metabolism and the higher amount of side effects, the treatment should be performed with extremely light forces and frequent monitoring.

Are dental color measuring devices CIE compliant?

OBJECTIVES: This in vitro study evaluated the accordance of dental color measurement devices with a Commission Internationale de l'Eclairage (CIE)-compliant reference system, by comparing the CIE lightness, chroma, and hue (L*C*h°) color coordinates of ceramic samples. METHODS: Four color measurement devices: Vita Easyshade® Advance (A); DeguDent Shadepilot™ (B); X-Rite® Shadevision (C); and Crystaleye Olympus (D), were compared with a CIE-compliant reference system by recording the L*C*h° color coordinates of ceramic samples matching the tooth colors of the Vita Linearguide 3D-Master®, under standardized test conditions. Differences between regression lines for the dental color measurement device data and regression lines for the CIE-compliant reference system data were evaluated. RESULTS: All devices offered high intraclass correlation coefficients (0.9771- 0.9999) for the L*C*h° color coordinates. The regression lines of the L* and C* coordinates for device A were steeper than those of the CIE-compliant reference system; the regression lines for devices B, C, and D were nearly parallel to those of the reference system, but with an offset. The regression lines of the h° coordinates for all devices were almost parallel to those of the reference system, with slopes near 1. Excluding the L* and h° coordinate measurements of device A, the measurements with the devices exhibited deviations from the reference system that were greater than those expected by chance (P < 0.0002). CONCLUSIONS: The dental color measurement devices assessed here offered excellent reproducibility, but showed significant deviations from the CIE-compliant reference system regarding the L*C*h° color coordinates.

A new method for volumetric evaluation of gingival recessions: a feasibility study.

BACKGROUND: This preliminary in vitro study, presented at the General Session of the International and American Association for Dental Research in 2010 (Barcelona, Spain), evaluates whether three-dimensional (3D) optical scanning and subsequent superimposing procedures could be used for reproducible volumetric evaluation of gingival recession. METHODS: Silicone impressions were taken of mandibular and maxillary master casts, and eight stone replicas of each master cast were produced. Each replica was scanned 10 times with a 3D optical system, and 3D datasets representing the computer-aided design reference models were calculated using a triangulation method. Marks designating gingival recession were scratched into the anterior segments of the replicas. The modified replicas were then scanned 10 times, and 3D datasets were calculated and subsequently superimposed. Differences in the volume of the gingival recession were recorded with reference to the initial data. RESULTS: The determination of gingival recession volume was highly reproducible. For all replicas, the 3D optical method showed small standard deviations and intraclass correlation coefficients between 0.997 and 0.999. CONCLUSIONS: This new method allows the reproducible volumetric evaluation of gingival recession marks on stone replicas. Additional clinical trials are necessary to confirm these in vitro findings. This method allows the operator to control the volumetric progression of periodontal soft tissue, for example, after root coverage procedures and to detect relapses at an early stage.

Effect of preparation depth differences on the marginal fit of zirconia crown copings: an in vitro study.

If optical scanning is used for crown fabrication, variability in preparation depth may be a limitation. Therefore, this preliminary laboratory study evaluated marginal fit in relation to preparation depth. Three dies with different preparation depths between the vestibular and oral regions were fabricated. Ten zirconia copings were manufactured for each die, and marginal gaps were examined. Increasing differences in preparation depth influenced the size of the marginal gap between the vestibulo-oral and mesiodistal regions significantly (P < .001). This study shows primarily that differences in preparation depth resulted in decreasing marginal precision.

Repeatability of color-measuring devices.

INTRODUCTION: The objective of this study was to evaluate the intra- and interdevice repeatability in different tooth regions using three color-measuring devices under clinical conditions. MATERIALS AND METHODS: Fifteen shade measurements (cervical, body, incisal) were recorded on 15 patients by one investigator using three color-measuring devices (VITA Easyshade compact, DeguDent Shadepilot, X-Rite ShadeVision). CIE Lab values were determined for all maxillary anterior teeth. Intraclass correlation coefficients (ICCs) were used to statistically analyze intra-and inter-device repeatability for different tooth regions. Color differences (ΔE) between measurements were also computed to evaluate the clinical acceptability of repeatability values. The data were evaluated using analysis of variance and Bonferroni's adjustment to control for multiple testing. Differences were deemed significant when P < 0.016. RESULTS: The three color-measuring devices generally exhibited high repeatability of color coordinates for all tooth regions (ICC > 0.516-0.986, ΔE < 3.03). In contrast, inter-device repeatability was lower for all tooth regions (ICC = 0.010-0.922, ΔE = 4.06-16.04). CONCLUSIONS: High intra-device repeatability of color coordinates could be achieved for all tooth regions when the same color-measuring device was used. However, because of low inter-device repeatability, results using different color-measuring devices are not comparable.