Practice‐based clinical evaluation of metal–ceramic and zirconia molar crowns: 3‐year results

This practice‐based study evaluates the clinical performance of conventionally luted metal–ceramic and zirconia molar crowns fabricated with pronounced anatomical core design and a prolonged cooling period of the veneering porcelain. Fifty‐three patients were treated from 07/2008 until 07/2009 with either metal–ceramic crowns (MCC) (high‐noble alloy + low‐fusing porcelain) or zirconia crowns (Cercon System, DeguDent, Germany). Forty‐nine patients (30 women/19 men) with 100 restorations (metal–ceramic: 48/zirconia: 52, mean observational period: 36·5 ± 6 months) participated in a clinical follow‐up examination and were included in the study. Time‐dependent survival (in situ criteria), success (event‐free restorations) and chipping rates (defects of the veneering ceramics) were calculated according to the Kaplan–Meier method and analysed in relation to the crown fabrication technique, using a Cox regression model (P < 0·05). Three complete failures (metal–ceramic: 1, zirconia: 2) were recorded (survival rate after 3 years: metal–ceramic: 97·6%, zirconia: 95·2%). Of the metal–ceramic restorations, 90·9% remained event‐free (two ceramic fractures, one endodontic treatment), whereas the success rate for the zirconia was 86·8% (two ceramic fractures, one endodontic treatment, one secondary caries). No significant differences in survival (P = 0·53), success (P = 0·49) and ceramic fracture rates (P = 0·57) were detected. The combination of a pronounced anatomical core design and a modified firing of the veneering porcelain for the fabrication of zirconia molar crowns resulted in a 3‐year survival, success and chipping rate comparable to MCC.     

Fracture strength of yttria-stabilized tetragonal zirconia polycrystals crowns with different design: an in vitro study

Objectives: The aim of this study was to evaluate the effect of different types and design of zirconia frameworks as well as the effect of different veneering ceramics on the fracture strength of crowns. The importance of different abutment materials was also evaluated. Materials and methods: Eighty cores, 40 in a fully‐sintered zirconia material and 40 in a pre‐sintered zirconia material were made. Twenty cores of each material were made with a core of even thickness shape (ES) and 20 were made with a core with anatomical shape (AS). The cores were divided into subgroups and veneered with one of two different veneering ceramics: a porcelain and a glass–ceramic material. In total eight groups of 10 crowns were made. They were all cemented onto abutments made of resin. One extra group of 10 AS, pre‐sintered zirconia cores veneered with glass–ceramic were made and cemented onto titanium abutments. All crowns underwent thermocycling and mechanical pre‐load and were finally loaded until fracture. Results: AS crowns withstood significantly higher loads than ES crowns (P‐value <0.001), and crowns with titanium abutments withstood significantly higher loads than crowns supported by abutments made of inlay pattern resin (P‐value <0.001). Three types of fracture were noted: minor and major fracture of the veneering ceramic, and complete fracture through core and veneer. ES crowns showed significantly more major fractures of the veneering ceramic than AS crowns. Conclusions: This in vitro study indicates that the design of the core, as well as the abutment support, significantly influences fracture load and fracture mode of yttria‐stabilized tetragonal zirconia polycrystals crowns. To cite this article :
Larsson C, El Madhoun S, Wennerberg A, Vult von Steyern P. Fracture strength of yttria‐stabilized tetragonal zirconia polycrystals crowns with different design: an in vitro study. Clin. Oral Impl. Res. 23 , 2012; 820–826.
doi: 10.1111/j.1600‐0501.2011.02224.x     

The efficacy of non‐narcotic analgesics on post‐operative endodontic pain: A systematic review and meta‐analysis

The objective of this review was to evaluate the efficacy of non‐narcotic analgesics including non‐steroidal anti‐inflammatory drugs (NSAIDs) and/or paracetamol in the treatment of post‐operative endodontic pain. Additionally, we aimed to examine the possible association of study covariates on the pain scores using meta‐regression analysis. An electronic search was performed in 2016. After data extraction and quality assessment of the included studies (n = 27, representing 2188 patients), meta‐analysis was performed using a random‐effect inverse variance method. Meta‐regression analysis was conducted to examine the associations between effect sizes and study‐level covariates (P < 0·05). The results showed that administration of non‐narcotic analgesic was more effective than placebo in the management of post‐operative pain, resulting in a lower pain scores with a standardised mean difference of ?0·50 (95% CI= ?0·70, ?0·30), ?0·76 (95%CI= ?0·95, ?0·56), ?1·15 (95% CI= ?1·52, ?0·78), ?0·65 (95% CI= ?1·05, ?0·26) for immediately after the procedure, 6?, 12? and 24 h post?operative follow‐ups (test for statistical heterogeneity: P = 0·000, P = 0·000, P = 0·000 and P = 0·001), respectively. Our meta‐regression analysis provided the evidence for association between some study covariates with treatment effect, each at different follow‐ups. We concluded that the clinicians can manage post‐operative endodontic pain by administration of NSAIDs and/or paracetamol. However, analgesic regimens should be considered as important determinants when prescribing a pharmacological adjuvant.     

Marginal adaptation of all-ceramic crowns on implant abutments

Background: Studies focusing on the marginal accuracy of all‐ceramic crowns on implant abutments are in short supply. Purpose: This study evaluated the marginal accuracy of all‐ceramic crowns on different implant abutments. Materials and Methods: Ninety‐six standardized maxillary central incisor crowns (48 alumina and 48 zirconia) were fabricated for each of the six test groups (n = 16) (Ti1, titanium abutments–alumina crowns; Ti2, titanium abutments–zirconia crowns; Al1, alumina abutments–alumina crowns; Al2, alumina abutments–zirconia crowns; Zr1, zirconia abutments–alumina crowns; Zr2, zirconia abutments–zirconia crowns). The crowns were adhesively luted using a resin luting agent. The marginal gaps were examined on epoxy replicas before and after luting as well as after masticatory simulation at 200× magnification. Results: The geometrical mean (95% confidence limits) marginal gap values before cementation, after cementation, and after masticatory simulation were group Ti1: 39(37–42), 57(53–62), and 49(46–53); group Ti2: 43(40–47), 71(67–76), and 64(59–69); group Al1: 57(54–61), 87(85–90), and 67(65–69); group Al2: 66(63–69), 96(90–101), and 75(72–78); group Zr1: 54(51–57), 79(76–82), and 65(63–67); and group Zr2: 64(60–68), 85(80–91), and 75(70–81). The comparison between non‐cemented and cemented stages in each group demonstrated a significant increase in the marginal gap values after cementation in all groups (p < .001), while the comparison between cemented and aged stages in each group showed a significant decrease in the marginal gap values in groups Al1, Al2, and Zr1 (p < .0001). This reduction was not significant for groups Ti1, Ti2, and Zr2 (p > .05). Conclusion: The marginal accuracy of all tested restorations meets the requirements for clinical acceptance.     

Randomized controlled clinical trial of customized zirconia and titanium implant abutments for canine and posterior single-tooth implant reconstructions: preliminary results at 1 year of function

Objectives: The aim of this study was to test whether or not customized zirconia abutments exhibit the same survival rates in canine and posterior regions as titanium abutments, and to compare the esthetic result of the two abutment types. Material and methods: Twenty‐two patients with 40 implants in posterior regions were included and the implant sites were randomly assigned to 20 customized zirconia and 20 customized titanium abutments. All‐ceramic (AC) and metal–ceramic (MC) crowns were fabricated. In all except two cases, the crowns were cemented on the abutments using resin or glass‐ionomer cements. Two zirconia reconstructions were screw retained. At baseline, 6 and 12 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque (Pl) and bleeding on probing (BOP) were assessed and compared with natural control teeth. Furthermore, the difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was evaluated by means of a spectrophotometer (Spectroshade). The data were analyzed with Student's unpaired t‐test, ANOVA and regression analyses. Results: Twenty patients with 19 zirconia and 12 titanium abutments were examined at a mean follow‐up of 12.6±2.7 months. The survival rate for reconstructions and abutments was 100%. No technical or biological problems were found at the test and control sites. Two chippings (16.7%) occurred at crowns supported by titanium abutments. No difference was found regarding PPD (meanPPD_ZrO2 3.4±0.7 mm, mPPD_Ti 3.3±0.6 mm), Pl (mPl_ZrO2 0.2±0.3, mPl_Ti 0.1±1.8) and BOP (mBOP_ZrO2 60±30%, mBOP_Ti 30±40%) between the two groups. Both crowns on zirconia and titanium abutments induced a similar amount of discoloration of the soft tissue compared with the gingiva at natural teeth (ΔE_ZrO2 8.1±3.9, ΔE_Ti 7.8±4.3). Conclusions: At 1 year, zirconia abutments exhibited the same survival and a similar esthetic outcome as titanium abutments.     

Five‐year results of a prospective randomised controlled clinical trial of posterior computer‐aided design–computer‐aided manufacturing ZrSiO4‐ceramic crowns

The aim of this prospective randomised controlled clinical trial was to evaluate the clinical outcome of shrinkage‐free ZrSiO₄‐ceramic full‐coverage crowns on premolars and molars in comparison with conventional gold crowns over a 5‐year period. Two hundred and twenty‐three patients were included and randomly divided into two treatment groups. One hundred and twenty‐three patients were restored with 123 ZrSiO₄‐ceramic crowns, and 100 patients received 100 gold crowns, which served as the control. All crowns were conventionally cemented with glass–ionomer cement. After an observation period of 6, 12, 24, 36, 48 and 60 months, the survival probability (Kaplan–Meier) for the shrinkage‐free ZrSiO₄‐ceramic crowns was 98·3%, 92·0%, 84·7%, 79% and 73·2% and for the gold crowns, 99%, 97·9%, 95·7%, 94·6% and 92·3%, respectively. The difference between the test and control group was statistically significant (P = 0·0027). The gold crowns showed a better marginal integrity with less marginal discoloration than the ceramic crowns. The most common failure in the ceramic crown group was fracture of the crown. The 60‐month results of this prospective randomised controlled clinical trial suggest that the use of these shrinkage‐free ZrSiO₄‐ceramic crowns in posterior tooth restorations cannot be recommended.     

Reliability and Failure Modes of Implant‐Supported Y‐TZP and MCR Three‐Unit Bridges

Purpose: Chipping within veneering porcelain has resulted in high clinical failure rates for implant‐supported zirconia (yttria‐tetragonal zirconia polycrystals [Y‐TZP]) bridges. This study evaluated the reliability and failure modes of mouth‐motion step‐stress fatigued implant‐supported Y‐TZP versus palladium‐silver alloy (PdAg) three‐unit bridges. Materials and Methods: Implant‐abutment replicas were embedded in polymethylmethacrylate resin. Y‐TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact‐tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step‐stress profiles and mouth‐motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. Results: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y‐TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two‐sided at 90% confidence intervals) for a “mission” of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y‐TZP. Conclusions: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials.     

In vitro chipping behaviour of all‐ceramic crowns with a zirconia framework and feldspathic veneering: comparison of CAD/CAM‐produced veneer with manually layered veneer

The purpose of this in vitro study was to assess the breaking load of zirconia‐based crowns veneered with either CAD/CAM‐produced or manually layered feldspathic ceramic. Thirty‐two identical zirconia frameworks (Sirona inCoris ZI, mono L F1), 0·6 mm thick with an anatomically shaped occlusal area, were constructed (Sirona inLab 3.80). Sixteen of the crowns were then veneered by the use of CAD/CAM‐fabricated feldspathic ceramic (CEREC Bloc, Sirona) and 16 by the use of hand‐layered ceramic. The CAD/CAM‐manufactured veneer was attached to the frameworks by the use of Panavia 2.0 (Kuraray). Half of the specimens were loaded until failure without artificial ageing; the other half of the specimens underwent thermal cycling and cyclic loading (1·2 million chewing cycles, force magnitude F_max = 108 N) before the assessment of the ultimate load. To investigate the new technique further, finite element (FE) computations were conducted on the basis of the original geometry. Statistical assessment was made by the use of non‐parametric tests. Initial breaking load was significantly higher in the hand‐layered group than in the CAD/CAM group (mean: 1165·86 N versus 395·45 N). During chewing simulation, however, 87·5% (7/8) of the crowns in the hand‐layered group failed, whereas no crown in the CAD/CAM group failed. The CAD/CAM‐produced veneer was significantly less sensitive to ageing than the hand‐layered veneer.     

Randomized-controlled clinical trial of customized zirconia and titanium implant abutments for single-tooth implants in canine and posterior regions: 3-year results

Objectives: The aim was to test whether or not zirconia abutments exhibit the same survival and technical/biological outcome as titanium abutments. Material and methods: Twenty‐two patients receiving 40 single‐tooth implants in canine and posterior regions were included. The implant sites were randomly assigned to 20 zirconia and 20 titanium abutments. All‐ceramic and metal–ceramic crowns were fabricated. At baseline, 6, 12 and 36 months, the reconstructions were examined for technical and biological problems. Probing pocket depth (PPD), plaque control record (PCR) and bleeding on probing (BOP) were assessed at abutments (test) and analogous contralateral teeth (control). Standardized radiographs of the implants were made and the bone level (BL) was measured referring to the implant shoulder on mesial (mBL) and distal sides (dBL). The difference of color (ΔE) of the peri‐implant mucosa and the gingiva of control teeth was assessed with a spectrophotometer. The data were statistically analyzed with Mann–Whitney Rank and Student's unpaired t‐tests. Results: Eighteen patients with 18 zirconia and 10 titanium abutments were examined at a mean follow‐up of 36 months (range 31.5–53.3 months). No fracture of an abutment or loss of a reconstruction was found. Hence, both exhibited 100% survival. At two metal–ceramic crowns supported by titanium abutments chipping of the veneering ceramic occurred. No difference of the biological outcome of zirconia and titanium abutments was observed: PPD ( 3.2 ± 1 mm, mPPD_Ti 3.4 ± 0.5 mm), PCR ( 0.1 ± 0.2, mPCR_Ti 0.1 ± 0.2) and BOP ( 0.4 ± 0.4, mBOP_Ti 0.2 ± 0.3). Furthermore, the BL was similar at implants supporting zirconia and titanium abutments ( 1.7 ± 1, 1.6 ± 1; mBL_Ti 2 ± 1, dBL_Ti 2.1 ± 1). Both, zirconia and titanium abutments induced a similar amount of discoloration of the mucosa compared with the gingiva at natural teeth ( 9.3 ± 3.8, ΔE_Ti 6.8 ± 3.8). Conclusions: At 3 years, zirconia and titanium abutments exhibited same survival and technical, biological and esthetical outcomes.     

Effect of finish line design on stress distribution in bilayer and monolithic zirconia crowns: a three‐dimensional finite element analysis study

This study evaluated the influence of different finish line designs and abutment materials on the stress distribution of bilayer and monolithic zirconia crowns using three‐dimensional finite element analysis (FEA). Three‐dimensional models of two types of zirconia premolars – a yttria‐stabilized zirconia framework with veneering ceramic and a monolithic zirconia ceramic – were used in the analysis. Cylindrical models with the finish line design of the crown abutments were prepared with three types of margin curvature radius (CR): CR = 0 (CR0; shoulder margin), CR = 0.5 (CR0.5; rounded shoulder margin), and CR = 1.0 (CR1.0; deep chamfer margin). Two abutment materials (dentin and brass) were analyzed. In the FEA model, 1 N was loaded perpendicular to the occlusal surface at the center of the crown, and linear static analysis was performed. For all crowns, stress was localized to the occlusal loading area as well as to the axial walls of the proximal region. The lowest maximum principal stress values were observed when the dentin abutment with CR0.5 was used under a monolithic zirconia crown. These results suggest that the rounded shoulder margin and deep chamfer margin, in combination with a monolithic zirconia crown, potentially have optimal geometry to minimize occlusal stress.     

Fracture load and chewing simulation of zirconia and stainless‐steel crowns for primary molars

Aesthetic alternatives to stainless‐steel crowns for restoring primary molars attain growing interest. We studied the mechanical properties of prefabricated zirconia crowns and conventional crowns. Three brands of prefabricated zirconia crowns were compared with computer‐aided design/computer‐aided manufacturing (CAD/CAM) zirconia crowns, preveneered stainless‐steel crowns, and conventional stainless‐steel crowns regarding: (i) fracture load under each of three conditions [no pretreatment, artificial aging in saliva for 12 wk, and after chewing simulation/thermocycling (1.68 × 10⁶ cycles/5–55°C)]; and (ii) survival rate during chewing simulation, considering decementation, fracture, chipping, fatigue cracks, and occlusal holes. Without pretreatment, the prefabricated zirconia crowns showed mean fracture load values between 893 N and 1,582 N, while the corresponding values for CAD/CAM zirconia crowns and preveneered stainless‐steel crowns were 2,444 N and 6,251 N. Preveneered stainless‐steel crowns showed significantly lower fracture loads after artificial aging (5,348 N after saliva aging; 3,778 N after chewing simulation) than without artificial aging, whereas the fracture load of zirconia crowns was not influenced negatively. The survival rate of the different groups of zirconia crowns and preveneered stainless‐steel crowns during chewing simulation was 100%, but only 41.7% for the stainless‐steel crowns. These in‐vitro data suggest that prefabricated zirconia crowns are aesthetically and durable alternatives to stainless‐steel crowns for primary molars.     

Self‐reported Bruxism ‐ associations with perceived stress,motivation for control,dental anxiety and gagging*

Summary To examine possible associations between self‐reported bruxism, stress, desirability of control, dental anxiety and gagging. Five questionnaires were distributed among a general adult population (402 respondents): the Perceived Stress Scale (PSS), Desirability of Control Scale (DC), Dental Anxiety Scale (DAS), Gagging Assessment Scale (GAS), and Bruxism Assessment Questionnaire. A high positive correlation between DAS and GAS (R = 0·604, P < 0·001) was found. PSS was negatively correlated with DC (R = ?0·292, P < 0·001), and was positively correlated with GAS (R = 0·217, P < 0·001) and DAS (R = 0·214, P < 0·001). Respondents who reported bruxing while awake or asleep showed higher levels of GAS, DAS and PSS than those who did not. There were no differences between the bruxers and the non‐bruxers (sleep and aware) with regard to the DC scores. The best predictors of awake bruxism were sleep bruxism (OR = 4·98, CI 95% 2·54–9·74) and GAS (OR = 1·10, CI 95% 1·04–1·17). The best predictors of sleep bruxism were awake bruxism (OR = 5·0, CI 95% 2·56–9·78) and GAS (OR = 1·19; CI 95% 1·11–1·27). Self‐reported sleep bruxism significantly increases the odds for awake bruxism and vice versa. Tendency for gagging during dental care slightly increases the odds of both types of self‐reported bruxism, but desirability of control is not associated with these phenomena.     

The Effect of Multiple Firings on Microtensile Bond Strength of Core‐Veneer Zirconia‐Based All‐Ceramic Restorations

Purpose: Differences in core and veneer coefficients of thermal expansion, firing shrinkage, and speed of increasing and decreasing the temperature may generate stress in veneered all‐ceramic restorations. Given the necessity of performing multiple firing cycles to achieve improved contour, color, and esthetics, the purpose of this study was to determine the effect of multiple firing cycles on the microtensile bond strength (MTBS) of zirconia core to the porcelain veneer in zirconia‐based all‐ceramic restorations. Materials and Methods: Thirty blocks (12 × 12 × 4 mm³) of semi‐sintered zirconia were machined and sintered according to manufacturer's instruction. Specimens were placed in three groups based on the number of firing cycles (4, 6, 8) for the veneering process. After veneering, the specimens were sectioned into microbars with 8 mm length and 1 mm cross‐section. Twenty sound microbars in each group were stressed to failure in a microtensile tester machine at 1 mm/min. Fractured specimens were surveyed under a scanning electron microscope and classified as cohesive in core, cohesive in veneer, and mixed. MTBS data were analyzed using one‐way ANOVA and Tukey test (p < 0.05). Results: The mean MTBS (MPa) after 4, 6, and 8 firing cycles were 30.33 ± 2.13, 27.43 ± 1.79, and 25.06 ± 1.76, respectively. There was a statistically significant difference between the bond strengths of each of the three groups (p < 0.001). Conclusion: Increase in firing cycles decreased MTBS. Most of the failures (90–95%) in all three groups were cohesive in the veneering porcelain and did not change as the number of firing cycles increased.     

Survival probability of zirconia‐based fixed dental prostheses up to 5 yr: a systematic review of the literature

Schley J‐S, Heussen N, Reich S, Fischer J, Haselhuhn K, Wolfart S. Survival probability of zirconia‐based fixed dental prostheses up to 5 yr: a systematic review of the literature.
Eur J Oral Sci 2010; 118: 443–450. © 2010 Eur J Oral Sci The purpose of this systematic review was to calculate the 5‐yr survival rates of all‐ceramic zirconia‐based fixed dental prostheses (FDPs) and to analyze technical and biological complications. An electronic literature search of MEDLINE (PubMed) was conducted independently by three reviewers to identify clinical studies from 1999 to 2009 and was completed by a manual search. Keywords and inclusion and exclusion criteria were well‐defined. The search revealed 399 titles and led to the final analysis of 18 full‐text articles. Nine studies met the inclusion criteria. Extracted data were statistically calculated into 5‐yr survival rates and 5‐yr complication‐free rates by using Poisson regression analysis. In total, 310, 3‐ to 4‐unit FDPs and 20 FDPs with more than 4 units were included. The estimated 5‐yr survival rate for all FDPs was 94.29% (95% CI: 58.98–99.32); 19 FDPs were lost as a result of catastrophic failures. The 5‐yr complication‐free rate regarding technical complications was 76.41% (95% CI: 42.42–91.60) with chipping being the most frequent complication. Regarding biological complications, the 5‐yr complication‐free rate was 91.72% (95% CI: 59.19–98.53). The survival rates of zirconia‐based short‐unit FDPs are promising. However, an important improvement of the veneering systems is required, and for FDPs with more units in function, further randomized, controlled clinical trials are necessary.     

The effect of oral appliances that advanced the mandible forward and limited mouth opening in patients with obstructive sleep apnea: A systematic review and meta‐analysis of randomised controlled trials

Oral appliances (OAs) have demonstrated efficacy in treating obstructive sleep apnea (OSA), but many different OA devices are available. The Japanese Academy of Dental Sleep Medicine supported the use of OAs that advanced the mandible forward and limited mouth opening and suggested an evaluation of their effects in comparison with untreated or CPAP. A systematic search was undertaken in 16 April 2012. The outcome measures of interest were as follows: Apnea Hypopnea Index (AHI), lowest SpO₂, arousal index, Epworth Sleepiness Scale (ESS), the SF‐36 Health Survey. We performed this meta‐analysis using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system. Five studies remained eligible after applying the exclusion criteria. Comparing OA and control appliance, OA significantly reduced the weighted mean difference (WMD) in both AHI and the arousal index (favouring OA, AHI: ?7·05 events h^?1; 95% CI, ?12·07 to ?2·03; P = 0·006, arousal index: ?6·95 events h^?1; 95% CI, ?11·75 to ?2·15; P = 0·005). OAs were significantly less effective at reducing the WMD in AHI and improving lowest SpO₂ and SF‐36 than CPAP, (favouring OA, AHI: 6·11 events h^?1; 95% CI, 3·24 to 8·98; P = 0·0001, lowest SpO₂: ?2·52%; 95% CI, ?4·81 to ?0·23; P = 0·03, SF‐36: ?1·80; 95% CI, ?3·17 to ?042; P = 0·01). Apnea Hypopnea Index and arousal index were significantly improved by OA relative to the untreated disease. Apnea Hypopnea Index, lowest SpO₂ and SF‐36 were significantly better with CPAP than with OA. The results of this study suggested that OAs improve OSA compared with untreated. CPAP appears to be more effective in improving OSA than OAs.     

DEEP Study: does EQ‐5D‐5L measure the impacts of persistent oro‐facial pain?

The EQ‐5D‐5L is a generic quality of life (QOL) measure widely used throughout the world, which has the advantage that it allows health‐state preferences to be elicited. The aim of this study was to examine whether: a) variation in the standardised reference period for EQ‐5D‐5L from ‘today’ to ‘the last month’ had a minimal clinically meaningful difference; (b) EQ‐5D‐5L had convergent validity with a multidimensional pain measure in quantifying the impacts of pain. As part of a larger study into the effectiveness and efficiency of care pathways for persistent orofacial pain (POFP) ( http://research.ncl.ac.uk/deepstudy ), participants with POFP (n = 100) completed two versions of the EQ‐5D‐5L at the same time with different reference periods (‘today’ vs. ‘last month’). Participants also completed the first section of the West Haven–Yale Multidimensional Pain Inventory (v3) to assess convergent validity. Two‐tailed nonparametric inferential statistics, intra‐class correlation coefficients (ICC), and within‐subject change scores were used to compare the two EQ‐5D‐5L versions. Convergent validity was assessed using Spearman's rho correlation coefficients. Health‐state valuations were significantly different (P < 0·01), and there was good similarity between the two versions' ICC 0·86 (95% CI 0·79–0·91). The within‐subject mean change was 0·03 (95% CI 0·01–0·06). For convergent validity, all relationships were significant (P < 0·05) and in the expected directions. EQ‐5D‐5L demonstrates sufficient convergent validity to be used with POFP, and a change in the standard reference period may be unnecessary if a multidimensional pain measure is also used.     

Analysis of load transfer and stress distribution by splinted and unsplinted implant‐supported fixed cemented restorations

Summary Controversy remains over the rehabilitation of implant‐supported restorations regarding the need to splint adjacent implant‐supported crowns. This study compared the effects of simulated occlusal loading of three implants restored with cemented crowns, splinted versus unsplinted. Three adjacent screw‐shaped implants were passively inserted into three holes drilled in a photo‐elastic model. Two combinations of cemented restorations were fabricated; three adjacent unsplinted and three adjacent splinted crowns. Strain gauges were connected to the implant necks and to the margins of the overlaying crowns. Fifteen axial static loads of 20‐kg loadings were carried out right after each other via a custom‐built loading apparatus. Strain gauges located on the implant neck supporting splinted restoration demonstrated significantly (P < 0·001) more strain (sum of strains = 3348·54 microstrain) compared with the single crowns (sum of strains = 988·57 microstrain). In contrast, significantly (P < 0·001) more strain was recorded on the strain gauges located on the restoration margins of the single crowns (sum of strains = 756·32 microstrain) when compared with splinted restorations (sum of strains = 186·12 microstrain). The concept of splinting adjacent implants to decrease loading of the supporting structures may require re‐evaluation. The clinical relevance of these findings needs further investigation.     

Fatigue resistance and failure mode of CAD/CAM composite resin implant abutments restored with type III composite resin and porcelain veneers

Objectives: This study assessed the fatigue resistance and failure mode of type III porcelain and composite resin veneers bonded to custom composite resin implant abutments. Material and methods: Using the CEREC 3 machine, 28 composite resin implant abutments (Paradigm MZ100) were fabricated along with non‐retentive type III veneers, milled either in ceramic Paradigm C (n=14) or in composite resin Paradigm MZ100 (n=14). The intaglio surfaces of the veneers were hydrofluoric acid etched and silanated (Paradigm C) or airborne‐particle abraded and silanated (MZ100). The fitting surface of the abutments was airborne‐particle abraded, cleaned, silanated and inserted into a bone level implant (10 mm, BLI RC). All veneers were luted with adhesive resin (Optibond FL) and a preheated light curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz, 30° angle) was simulated, starting with a load of 40 N, followed by stages of 80, 120, 160, 200, 240 and 280 N (20,000 cycles each). Samples were loaded until fracture or to a maximum of 140,000 cycles. Groups were compared using the life table survival analysis (Log rank test at P=0.05). Previously published data using same‐design zirconia abutments were included for comparison. Results: Paradigm C and MZ100 specimens fractured at an average load of 243 and 206 N (survival rate of 21% and 0%), respectively, with a significant difference in survival probability (P=0.02). Fractured specimens presented mixed failure modes and solely adhesive failures were not observed. The survival of composite resin abutments was similar to that of identical zirconia abutments from a previous study (P=0.76). Conclusions: Non‐retentive porcelain veneers bonded to custom composite resin implant abutments presented a higher survival rate when compared with composite resin veneers. Survival of composite resin abutment did not differ from zirconia ones. To cite this article:
Magne P, Oderich E, Boff LL, Cardoso AC, Belser UC. Fatigue resistance and failure mode of CAD/CAM composite resin implant abutments restored with type III composite resin and porcelain veneers.
Clin. Oral Impl. Res. 22 , 2011; 1275–1281.
doi: 10.1111/j.1600‐0501.2010.02103.x     

Fracture force of tooth-tooth- and implant-tooth-supported all-ceramic fixed partial dentures using titanium vs. customised zirconia implant abutments

Objectives: Tooth‐coloured customised implant abutments and full ceramic supraconstructions thereon can be made of zirconia by computer‐aided manufacturing (CAM). The aim of this study was to examine the potential limits of zirconia three‐unit fixed partial dentures made on customised zirconia implant abutments in implant‐tooth supported cases. Material and methods: Rigidly mounted implants (XiVE‐S diameter 3.8 mm; length 11 mm; Friadent, Germany) were placed in PMMA‐moulds pairwise with human molars at a distance of 10 mm in groups #1 and #2. Control group #3 consisted of two molars without implant involvement. Beforehand all molar roots were covered with polyether (Impregum: 3 M Espe, Germany) to simulate periodontal mobility. The abutments in #1 were individually fabricated from CerconBase and luted on experimental titanium bases (both: DeguDent, Germany). In #2, industrially prefabricated titanium abutments (Friadent) were used. All molar teeth were provided with a circumferential chamfer preparation. Three‐unit fixed partial dentures were fabricated from CerconBase/CerconKiss in a CAM‐process (Material/devices: DeguDent) for all test groups (n=8/group). All fixed partial dentures were cemented with RelyXUnicem (3 M Espe), thermomechanically loaded (TCML=1.2 × 10⁶× 50 N; 6000 × 5°/55°) and fracture tested in a Universal Test Machine (UTM 1446: Zwick, Germany). Results: None of the dentures failed during TCML, and the Cercon abutments showed no damage either to the bonding surface to titanium or to the ceramic itself. Two fixation screws in group #1 broke towards the end of TCML. Fracture test result (Median and 25‐/75‐Percentiles) were: #1 1190 (1046/2008), #2 991 (832/1402), #3 1331 (1224/1428). Conclusions: All restoration alternatives showed sufficient fracture resistance for posterior regions.     

Management of shortened dental arches and periodontal health: 5‐year results of a randomised trial

In a multicentre randomised trial (German Research Association, grants DFG WA 831/2‐1 to 2‐6, WO 677/2‐1.1 to 2‐2.1.; controlled‐trials.com ISRCTN97265367), patients with complete molar loss in one jaw received either a partial removable dental prosthesis (PRDP) with precision attachments or treatment according to the SDA concept aiming at pre‐molar occlusion. The objective of this current analysis was to evaluate the influence of different treatments on periodontal health. Linear mixed regression models were fitted to quantify the differences between the treatment groups. The assessment at 5 years encompassed 59 patients (PRDP group) and 46 patients (SDA group). For the distal measuring sites of the posterior‐most teeth of the study jaw, significant differences were found for the plaque index according to Silness and Löe, vertical clinical attachment loss (CAL‐V), probing pocket depth (PPD) and bleeding on probing. These differences were small and showed a slightly more unfavourable course in the PRDP group. With CAL‐V and PPD, significant differences were also found for the study jaw as a whole. For CAL‐V, the estimated group differences over 5 years amounted to 0·27 mm (95% CI 0·05; 0·48; P = 0·016) for the study jaw and 0·25 mm (95% CI 0·05; 0·45; P = 0·014) for the distal sites of the posterior‐most teeth. The respective values for PPD were 0·22 mm (95% CI 0·03; 0·41; P = 0·023) and 0·32 mm (95% CI 0·13; 0·5; P = 0·001). It can be concluded that even in a well‐maintained patient group statistically significant although minor detrimental effects of PRDPs on periodontal health are measurable.