Evaluation of masticatory efficiency and OHRQoL in implant-retained overdenture with different numbers of implant in the edentulous mandible: a one-year follow-up prospective study.

PURPOSE: The aim of this article is to evaluate to the masticatory function performance and Oral Health-related Quality of Life (OHRQoL) in implant-retained overdenture compared with different implant number placements in the edentulous mandible. METHODS: From 2013 to 2015, each patients received 3 implants (iSy-Implant, Camlog, Wimsheim, Germany) in intraforaminal mandible (34, 41/31, 44). After operation, inserted implants were gradually loaded and incorporated into an overdenture with a self-aligning attachment system (Locator abutments) in 3 + 3 + 3 months. Five checked points were performed chewing cycle test with multicolored chewing gum and OHIP-G14 questionnaire and a sum score questionnaire as following: pre-operation, one implant load (41/31), two implants loaded (33,43), three implants loaded and 1-year follow up. RESULT: A total of 10 patients with 30 implants were placed, the survival rate of the implants was 100% within 1-year follow-up. Regarding the masticatory function analysis, for the higher number of chewing cycles, the higher mixing rate was observed. After 1 year, the inter-mixing rate without significant changes was found compared to the time after three implants were loaded with attachment system. The mean value of OHIP-G14 was 30.4 preoperatively, 21.1 after loading the first locator, 10.7 after loading two locator abutments, and 3.2 after loading all three locator abutments. After 1 year, OHIP-G14 was 2.6 without significantly changed. The mean of the sum score was 15.5 preoperatively, 27.8 after activation of the first locator, 39.4 after activation of two locators, 46.2 after activation of all three locators, and 47.3 after 1 year. An increase of 0.7 sum score units per time point was observed. No significance was detectable, analogous to OHIP-G14, compared to the time of activation of all three locator setups (p-value = 0.22). CONCLUSIONS: A significant improvement in masticatory function performance and OHRQoL was evaluated with the increasing number of implants with locator attachment in edentulous mandible. With the investigation of the OHIP-G14 and sum score, the results of patient report outcome might be associated with the increase in the number of implants.

Influence of cold atmospheric-pressure-plasma in combination with different pretreatment methods on the pull-off tensile load in two-piece abutment-crowns: an in-vitro study.

BACKGROUND: In implant prosthetic dentistry, the adhesive connection of individualized ceramic crowns and prefabricated titanium bases leads to several benefits. However, the durability of the bonding could be a weak point and especially depends on sufficient surface pretreatment. Cold atmospheric-pressure plasma (CAP) is a pretreatment method that should improve the surface properties without physical damage. Thus, the purpose of this study was to investigate the influence of CAP treatment on pull-off tensile load in two-piece abutment crowns. METHODS: Eighty zirconia crowns and titanium bases were divided into eight groups (n = 10) according to their surface pretreatment prior to cementation with Panavia V5: no treatment (A); sandblasting (B); 10-MDP primer (C); sandblasting and primer (D); CAP (AP); sandblasting and CAP (BP); CAP and primer (CP); sandblasting, CAP and primer (DP). The specimens were thermocycled (5°/55°, 5000 cycles), and then the pull-off tensile load (TL) was measured. Statistical analyses were performed using three-way ANOVA with Tukey post-hoc and Fisher's exact tests. RESULTS: The results showed that the TL was highest in group D (p < 0.0001). Some combinations of different treatments led to effects that were greater than the sum of the individual effects. These effects were modified by interactions. Only in combination with primer, CAP treatment had a small but positive significant effect (group CP vs. C and CP vs. AP, p < 0.0001) which however did not come close to the strong interaction effect that resulted from the combination of sandblasting and primer. CONCLUSION: Within the limitations of this study, CAP treatment cannot be recommended in this specific field of indication due to its unreliable influence on TL in combination with other pretreatment methods.

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.

Biomechanical Characterization of a New Acellular Dermal Matrix for Oral Soft Tissue Regeneration.

OBJECTIVES: Acellular dermal matrices (ADM) are a suitable alternative to autogenous soft tissue grafts (ASG). The aim of this study was to analyze the biomechanical properties and architectural features of ASG and ADM. MATERIALS AND METHODS: ASG were harvested from the hard palate of fresh frozen body donors as connective tissue grafts and compared to ADM of porcine origin (NovoMatrix, NM; mucoderm, MD). Maximum load (ML, Newton [N]) and expansion (E, [mm]) were measured after rehydration in saline solution by tensile strength measurement. Light microscopy (LM) and scanning electron microscopy (SEM) were performed to analyze the architectural features of ASG and ADM in high resolution. RESULTS: ASG demonstrated a significantly decreased ML compared to NM and MD (p < 0.0001 and p = 0.019). NM showed a significantly increased ML compared to MD (p = 0.001). ASG demonstrated a non-significantly reduced E compared to NM (p = 0.13) and a significantly increased E compared to MD (p = 0.025). NM showed an increased E compared to MD (p < 0.0001). LM and SEM highlighted the surface characteristics and internal structures of ASG and ADM, such as the surface compact layer of MD and the densely packed, parallel running and ordered collagen fibers of NM and MD. CONCLUSIONS: Significant differences concerning the biomechanical properties and architectural features of ASG, and ADM were found. CLINICAL RELEVANCE: Information about the biomechanical properties and architectural features of ASG and ADM can contribute to a better understanding of the clinical performance and extend the application area.

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.

Interradicular Root Canals in Mandibular First Molars: A Literature Review and Ex Vivo Study.

INTRODUCTION: Successful endodontic treatment vastly depends to a high degree on an accurate knowledge of root canal system morphology. It is a prerequisite to be aware of all possible reservoirs where bacteria and/or toxins can persist, compromising the surrounding tissues; such knowledge results in endodontic success. METHODS: The presence of interradicular canals and diverticula between the pulp chamber floor and the bifurcation area surface of 117 mandibular first molars was investigated. Access cavities were prepared, the teeth were embedded in plastic, and the pulp chambers were flooded with methylene blue and then centrifuged. An average of 4.2 (0.145 ± 0.03 mm thickness) slices per tooth were obtained by means of a diamond band saw. The presence of interradicular canals and diverticula was investigated using a light microscope (125×). RESULTS: Interradicular canals were observed in 9 teeth. Seven teeth had 1 interradicular canal, and 2 teeth had 2 interradicular canals. Diverticula (blind interradicular canals) were observed in 11 teeth originating either on the pulp chamber floor or the bifurcation side. The number of diverticula per tooth varied between 1 and 5 and originated in 3 teeth in the pulp chamber floor and 8 teeth in the bifurcation area. Two teeth had both 1 interradicular canal and 3 diverticula. Of the 117 mandibular molars investigated, 18 had either 1 or 2 interradicular canals, 1 to 5 diverticula, or an interradicular canal and 3 diverticula. CONCLUSIONS: Based on the results obtained with this ex vivo study and because of the difficulties involved in the clinical performance of mechanical cleaning of possibly existing interradicular canals, it is highly recommended to perform thorough chemical cleaning and disinfection of the pulp chamber floor area in order to enhance the sealing possibility of such structures and minimize treatment failure.

Preload, Coefficient of Friction, and Thread Friction in an Implant-Abutment-Screw Complex.

PURPOSE: To examine the screw preload, coefficient of friction (COF), and tightening torque needed to overcome the thread friction of an implant-abutment-screw complex. MATERIALS AND METHODS: In a customized load frame, 25 new implant-abutment-screw complexes including uncoated titanium alloy screws were torqued and untorqued 10 times each, applying 25 Ncm. RESULTS: Mean preload values decreased significantly from 209.8 N to 129.5 N according to the number of repetitions. The overall COF increased correspondingly. There was no comparable trend for the thread friction component. CONCLUSION: These results suggest that the application of a used implant-abutment-screw complex may be unfavorable for obtaining optimal screw preload.

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.

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%).

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.

A bar-retained overdenture as an external fixator device in a three-dimensional CAD/CAM-based surgical reconstruction of the mandible.

Large defects of the human face often cause esthetic as well as functional disorders. We present a new technique for reconstruction of the mandible with prosthodontic rehabilitation in a single surgery, using the implant-supported, bar-retained overdenture as an external fixator. A 58-year-old patient presented with a near total defect of the mandible after cancer resection. For rehabilitation, the mandibular condyles were virtually positioned in the centre of the fossae, and four dental implants were planned. The position of the fibula segments as well as their angulation and lengths were adapted to the implant position. To transfer this plan into surgery, a combined cutting/implant drilling guide was computer-aided printed. To provide the correct angulation of the fibula segments, a CAD/CAM dental arch-bar was made from titanium, fulfilling three functions: to bear the provisional prosthesis; to stabilize the molded fibula as an external fixator; and to position the complete fibula with the prosthesis in a correct relation to the upper jaw and occlusion, as indicated by the prosthesis. This innovative approach of combined prosthodontic and reconstructive rehabilitation could shorten the total reconstruction/rehabilitation time and avoid the need for additional extended surgeries.

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.

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.

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.