In vitro Fracture strength and hardness of different computer-aided design/computer-aided manufacturing inlays.

OBJECTIVE: The purpose of this study was to examine the fracture strength and surface microhardness of computer-aided design/computer-aided manufacturing (CAD/CAM) materials in vitro. MATERIALS AND METHODS: Mesial-occlusal-distal inlays were made from five different CAD/CAM materials (feldspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). RESULTS: Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. CONCLUSION: Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation.

Influence of endodontic treatment, post insertion, and ceramic restoration on the fracture resistance of maxillary premolars.

AIM: To investigate the effects of endodontic treatment, post placement and ceramic restoration type on the fracture resistance of premolars. METHODOLOGY: One hundred and twenty teeth maxillary premolars were allocated to four groups (A-D; n = 30). In group A, mesio-occlusal-distal-inlays with a buccal and palatal wall of 2 mm (MOD), in group B partial onlays with palatal cusp coverage and in group C total onlays with buccal and palatal cusp coverage were prepared. Group D served as untreated controls. Groups A-C were divided into three subgroups (n = 10): (i) teeth received solely the described preparations, (ii) teeth were root filled, (iii) teeth were root filled and quartz fibre posts were placed. Teeth were restored using Computer-assisted design/computer-assisted machining-ceramic-restorations and subjected to thermo-mechanical-loading; subsequently, the buccal cusp was loaded until fracture. RESULTS: Group D revealed significantly higher fracture resistance [mean (standard deviation)] [738 (272) N] compared to all other groups (P < 0.05; post hoc test Dunnett). For groups A-C, fracture resistance was significantly affected by the restoration type (P = 0.043) and endodontic treatment/post placement (P = 0.039; 2-way anova). Group A [380 (146) N] showed significantly lower fracture resistance compared to group B [470 (158) N] (P = 0.048; post hoc test Tukey). Compared to non-endodontically treated teeth [487 (120) N], root filled teeth revealed significantly lower fracture resistance [389 (171) N] (P = 0.031). CONCLUSION: The restoration of cavities with a remaining wall thickness of 2 mm using ceramic MOD-inlays is inferior with respect to the fracture resistance compared to partial onlay restorations. Root filled teeth without post placement show lower fracture resistance compared to non-endodontically treated teeth.

A preliminary survey of impression trays used in the fabrication of fixed indirect restorations.

PURPOSE: A variety of impression trays are used in the fabrication of fixed indirect restorations. Impressions used in the construction of fixed indirect restorations were examined for tray type, manner of use, and overall impression quality. MATERIALS AND METHODS: A commercial dental laboratory provided 1403 impressions used to fabricate fixed indirect restorations during a 3-month period. Impressions were examined for tray type, quantity and type of recorded abutments, the impression of intact teeth adjacent to and opposing the abutment, the presence of the canine in the impression, and an assessment of the quality of the impression. RESULTS: A majority of trays examined were plastic (864, or 61.6%). Dual-arch trays comprised 73.1% of the total. Most of these were metal posterior (n = 499) or plastic posterior (n = 280). Among partial dual-arch impressions, 561 (55.7%) were for the single abutment restoration, bounded by intact teeth anterior and posterior, and with an intact opposing tooth. Eleven percent of plastic dual-arch impressions failed to register the canine. Regarding restoration type, there were 955 impressions for the single-tooth crown, 46 for implant-supported restorations, and 11 for veneers. Twenty impressions were for posts, inlays, or onlays. Impressions for multiple single-tooth crowns and fixed partial dentures comprised the remainder. In terms of overall quality, 85.3% of impressions were excellent or good. The lowest performance in terms of excellent quality was in the anterior plastic single-arch impression (44.8%), whereas the best rate of excellent quality noted was for the posterior dual-arch impression (82.4%). CONCLUSIONS: Within the limitations of this study, dual-arch trays were the most commonly used tray. Recommendations for the use of the dual-arch tray were not followed in a substantial number of impressions examined.

Tension-Free Inlay Repair of Large Hiatal Hernias Using Dual-Sided Composite PTFE/ePTFE Meshes in Laparoscopic Surgery for Gastroesophageal Reflux Disease.

BACKGROUND: Patients with gastroesophageal reflux disease (GERD) also frequently suffer from concomitant hiatal hernia. It has been described that a preoperative hiatal hernia of ≥3 cm is associated with a more than threefold relative risk for reflux symptom recurrence after fundoplication without mesh reinforcement. In this report, we describe our experience with the implantation of dual-sided composite PTFE/ePTFE meshes in a tension-free fashion during laparoscopic antireflux surgery (LARS). METHODS: A prospective database containing data of all patients undergoing LARS and hiatal hernia repair with mesh implantation from January 2009 until December 2014 was interrogated. Ten patients with preoperative esophageal high resolution manometry and 24-hour pH impedance monitoring because of symptoms suggestive of GERD who received hiatal repair using dual-sided meshes in inlay technique were identified and included in this analysis. RESULTS: There were no conversions to open surgery in the study group. Median operative time was 138 minutes (interquartile range Q1-Q3: 119-151 minutes) and average length of postoperative stay was 3.5 days (interquartile range Q1-Q3: 2.3-4.0 days). During a median follow-up period of 43.3 months (interquartile range Q1-Q3: 18.9-47.1 months), no redo operations had to be performed. Noteworthy, 2 patients complained about dysphagia (20%) during follow-up, but symptoms resolved after endoscopic interventions. CONCLUSIONS: Tension-free inlay repair of large hiatal hernias using dual-sided composite PTFE/ePTFE meshes during LARS provides promising results. It provides satisfactory symptom relief and prolonged control of GERD. Further studies to validate its efficiency in a larger collective are needed.

Fracture resistance of endodontically treated teeth restored with ceramic inlays and different base materials.

This study evaluated the fracture resistance of endodontically treated teeth restored with different base materials and mesioocclusal-distal (MOD) ceramic inlays. Fifty mandibular molars were assigned into five groups (n=10 per group). Group1 (control) comprised intact molar teeth without any treatment. Teeth in other groups were subjected to root canal treatment and restored with MOD ceramic inlays on different base materials. In Group 2, base material was zinc phosphate cement; Group 3's was glass ionomer cement; Group 4's was composite resin, and Group 5's was composite resin reinforced with fiber. Finally, a continuous occlusal load was applied until fracture occurred. Mean fracture resistance of Group 1 (3,027 N) was significantly higher than the other groups (890, 1,070, 1,670, 1,226 N respectively). Fracture resistance of Group 4 was statistically comparable with Group 5 and significantly higher than Groups 2 and 3 (p<0.05; Tukey's HSD). Use of different base materials under ceramic inlay restorations could affect the fracture resistance of endodontically treated teeth.

Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

Two ceramic materials compared for the production of CEREC inlays.

Two ceramic materials, MGC Dicor and Vitablocs Mark II, were compared in vitro for the quality of fit of CEREC inlay restorations. The inlays made from Vitablocs Mark II fitted the inlay preparation significantly better than those made from MGC Dicor.

Surface integrity of composite inlays following ultrasonic vibration.

PURPOSE: To assess the effect of ultrasonic vibration on the surface integrity of a resin composite inlay. MATERIALS AND METHODS: Ultrasonic vibration in the form of a scaling tip oriented either parallel or perpendicular to the surface was applied to 2 mm thick, 10 mm wide composite discs and the experiment was repeated with the probe oriented perpendicular using composite or rubber shields. The indentations produced were measured using a form Talysurf profilometer. The surfaces of the discs were also observed using scanning electron microscopy. Five discs were used for each experiment. RESULTS: Both parallel and perpendicular orientations produced an indentation with a scattering of composite debris. A significant increase in the depth of indentation occurred if the vibrations of the ultrasonic scaler were oriented parallel to the composite surface (Two sample t- test, P < 0.01). The presence of a composite shield significantly reduced (Mann-Whitney, P < 0.05) the depth of indentation but produced roughening of the surface with impaction of material from the shield onto the surface. The rubber shield, however, polished the surface significantly smoother than the control specimens (Mann-Whitney, P < 0.05). Microscope slide separation was used to measure the thickness of composite luting agent following vibration with an ultrasonic scaling tip with and without a protective sleeve. There was a significantly thinner film of luting agent when an unsleeved scaler was used (ANOVA, P < 0.001). Although an unguarded tip oriented perpendicular to the surface appears to result in the best energy transfer for a thin layer of composite luting agent, it does, however, create minimal surface damage.

Possibilities for restoration of severely destroyed dental crowns with inlays.

In everyday dentistry practice cases with diffuse destruction of masticatory teeth are common. In the study presented the possibilities of their restoration with metal or metal-ceramic inlays are reviewed. Twenty-one inlays were fabricated, 16 from metal and 5 from metal-ceramic. The quality of the fabricated obturations were assessed immediately after they were cemented and one year later. The results showed that this is a reliable method. During the studied period there were no changes in the inlays, the teeth tissues and marginal adaptation.

[Study on improvement of adaptation for inlay made by dental CAD/CAM CEREC 2 system].

The purpose of this study was to evaluate the effect of changes in the tapering angle of inlay casting, adhesive gap and cavosurface margin on the cavity wall adaptability of the inlay made by the dental CAD/CAM CEREC 2 system. Designed inlay castings were fabricated at three different tapering angles: 0, 3, and 6 degrees. Adhesive gap of 0, -50, -100 microns and adhesive gap of 0 micron combined with the adjustment of cavosurface margin at 2 and 4 pixels were also evaluated. The difference between the direct method with powder and the indirect method without powder were compared under all conditions. The gap between the castings and cavity walls were assessed under a telescopic microscope. Internal adaptation of castings was determined to measure the cement thickness on the surfaces sectioned in the central portion of the cavity. It was found that inlays fabricated at 3 or 6 degree taper exhibited less gap at the side wall of the cavity than those without taper. The indirect method without powder also showed less gap when compared with the direct method with powder. Marginal gap and the cement width at the side wall of the cavity were reduced when the adhesive gap was modified to -50 or -100 microns or the cavosurface margin was adjusted at 2 or 4 pixels in the outer margin. The results suggested that the indirect method with the taper of 3 or 6 degrees of inlay casting, or with adjustment of adhesive gap to -50 microns provided the best adaptability between the castings and cavity walls.

[Ceramic inlays and onlays]. / Keramische inlays en onlays.

Large direct composite restorations can induce shrinkage related postoperative sensitivity. Indirect resin-bonded (tooth colored) restorations may perhaps prevent these complaints. Indirect bonded ceramics are especially attractive because of their biocompatibility and esthetic performance. Several procedures and techniques are currently available for the fabrication of ceramic restorations: firing, casting, heat-pressing and milling. In this article the different systems are described. Advantages, disadvantages and clinical performance of ceramic inlays are compared and discussed.

All-ceramic partial coverage restorations--midterm results of a 5-year prospective clinical splitmouth study.

OBJECTIVES: Midterm-evaluation of a 5-year prospective clinical splitmouth-investigation on survival rate and long-term behavior of all-ceramic partial coverage restorations (PCRs) on molars. Pressed ceramic and CAD/CAM fabricated PCRs were compared. METHODS: 80 vital molars of 25 patients were restored with all-ceramic PCRs (40 IPS e.max Press*[IP] and 40 ProCAD*[PC]). IP-PCRs were heat pressed following the lost-wax method. PC-PCRs were fabricated with Cerec 3** and Cerec InLab** CAD/CAM system (**Sirona Dental Systems, Bensheim, Germany). All PCRs were adhesively luted with a light-polymerizing composite (Syntac*/Tetric*) (*Ivoclar Vivadent, Schaan, Liechtenstein). Clinical reevaluations were performed at baseline and 13, 25, and 36 months after insertion of the PCRs according to the modified United States Public Health Services (USPHS) criteria. Absolute failures were demonstrated by Kaplan-Meier survival rate. RESULTS: After an observation time up to 3 years, survival rate of IP-PCRs was 100% and 97% for PC-PCRs due to one severe fracture. The PC-PCR had to be replaced after 9 months. Secondary caries and endodontic complications did not occur. Increased clinical service time resulted in significant decrease of marginal adaptation (p=0.031) and enhanced marginal discoloration (p<0.0001). Both PCR ceramic materials demonstrated significant deteriorations in color match (p<0.0001) and surface roughness (p<0.0001), IP-PCRs were significantly more affected (p< or =0.005). Regarding anatomic form IP-PCRs performed significantly better (p=0.0012). CONCLUSION: Pressed ceramic and CAD/CAM fabricated partial coverage restorations exhibited a reliable treatment option to restore larger defects in posterior teeth. Marginal degradation of the resin cement and deterioration of the all-ceramic materials during clinical function determine the clinical long-term performance of partial coverage restorations.

[A three-year clinical evaluation of ceramic optimized polymer posterior inlays].

PURPOSE: To evaluate the clinical results of ceramic optimized polymer (Targis) posterior inlays. METHODS: 345 type I cavities were divided into two groups: 170 in Targis inlays group (42 premolars and 128 molars) and 175 in control group (composite resin inlays, 45 premolars and 130 molars). The clinical effects of Targis inlays and composite resin inlays in posterior teeth were compared in marginal discoloration, marginal adaption, secondary caries, anatomic shape integrity, fractures of tooth and color match 3 years later. The data were analyzed using Chi-square test. RESULTS: 3 years after treatment, 166 Targis inlays were followed up, 2 had marginal discoloration, 158 had good marginal adaption, 162 had anatomic shape integrity, 1 had secondary caries, 161 had color match, and 5 had fractures of teeth. 169 composite resin inlays were followed up, 27 had marginal discoloration, 134 had good marginal adaption, 150 had anatomic shape integrity, 20 had secondary caries, 164 had color match,5 had fractures of teeth. The marginal discoloration, marginal adaption, secondary caries, anatomic shape integrity of Targis inlays were better than that of composite resin inlays (P < 0.05), but fractures of teeth was not different between inlays in the two group (P > 0.05). CONCLUSION: Targis posterior inlays is a good newly developed prosthesis.

Fit of crown wax patterns after removal from the die.

The effects of loading the wax pattern before investment was determined. Various loads were placed on the pattern after its margin was remodeled. The patterns were replaced on the die with a load of 50 gm before investment. For loads of 0, 250, and 1000 gm, the average elevation of the pattern on the die was found to be greater by 29, 56, and 19 micron, respectively, than before removal from the die. Repetitive loading showed that the plastic deformation in wax was less in the second than in the first cycle for a specific load. This decrease in plastic deformation may explain the improved adaptation of the pattern after a load of 1000 gm.

An evaluation of techniques for finishing margins of gold inlays.

The following conclusions on finishing margins of gold inlays were reached: 1. Instruments should be rotated perpendicular to the margin from gold to enamel. 2. Green stones produce rough surfaces that are not easily smoothed by finer instruments. 3. Hand burnishers and rubber points are not effective in producing gross marginal closure. 4. The best instruments for finishing occlusal margins are round steel burs, finishing burs, or white finishing stones. 5. When finishing occlusal margins, it is important to use an instrument small enough to gain access to the depth of grooves and fissures. 6. Proximal preparations made with a secondary flare yield castings with better "as cast" and finished margins than those preparations made with a butt joint. 7. The best instruments for finishing proximal margins are flexible paper discs. Usually, one fine sand or fine cuttle discs are necessary. 8. There is an indication that castings made from slightly overwaxed patterns can be finished to produce better margins than those made from patterns waxed exactly to the margins.