Accelerated Fatigue Resistance of Thick CAD/CAM Composite Resin Overlays Bonded with Light- and Dual-polymerizing Luting Resins

PURPOSE

To evaluate the accelerated fatigue resistance of thick CAD/CAM composite resin overlays luted with three different bonding methods.

MATERIALS AND METHODS

Forty-five sound human second mandibular molars were organized and distributed into three experimental groups. All teeth were restored with a 5-mm-thick CAD/CAM composite resin overlay. Group A: immediate dentin sealing (IDS) with Optibond FL and luted with light-polymerizing composite (Herculite XRV). Group B: IDS with Optibond FL and luted with dual-polymerizing composite (Nexus 3). Group C: direct luting with Optibond FL and dual-polymerizing composite (Nexus 3). Masticatory forces at a frequency of 5 Hz were simulated using closed-loop servo-hydraulics and forces starting with a load of 200 N for 5000 cycles, followed by steps of 400, 600, 800, 1000, 1200 and 1400 N for a maximum of 30,000 cycles. Each step was applied through a flat steel cylinder at a 45-degree angle under submerged conditions.

RESULTS

The fatigue test generated one failure in group A, three failures in group B, and no failures in group C. The survival table analysis for the fatigue test did not demonstrate any significant difference between the groups (p = 0.154). The specimens that survived the fatigue test were set up for the load-to-failure test with a limit of 4600 N. The survival table analysis for the load-to-failure test demonstrates an average failure load of 3495.20 N with survival of four specimens in group A, an average failure load of 4103.60 N with survival of six specimens in group B, and an average failure load of 4075.33 N with survival of nine specimens in group C. Pairwise comparisons revealed no significant differences (p < 0.016 after Bonferroni correction).

CONCLUSION

Within the limitations of this in vitro study, it can be concluded that although the dual-polymerizing luting material seems to provide better results under extreme conditions, light-polymerizing luting composites in combination with IDS are not contraindicated with thick restorations.

Microshear Bond Strength of Tri-Calcium Silicate-based Cements to Different Restorative Materials

PURPOSE

To evaluate the microshear bond strength of tri-calcium silicate-based materials to different restorative materials.

MATERIALS AND METHODS

Thirty-five disks of TheraCal LC and Biodentine were fabricated using teflon molds according to manufacturers' instructions. Then the specimens were randomly divided into 7 groups according to the materials applied: Fuji IX, Fuji II, Equia Fil, Vertise Flow, Filtek Bulk Fill Posterior Restorative, Filtek Z250 with Prime&Bond NT and with Clearfil SE Bond. All restorative materials were placed onto the disks using tygon tubes. Following a storage period, the specimens underwent microshear bond strength testing in a universal testing machine, and fracture modes were analyzed. Data were analyzed using one-way ANOVA and Tukey's post-hoc test.

RESULTS

For all restorative materials, TheraCal LC showed significantly higher μSBS values compared to Biodentine. GIC based materials showed the lowest μSBS for TheraCal and Biodentine. For Biodentine, Filtek Z250 applied with Prime&Bond NT and Filtek Bulk Fill Posterior Restorative applied with Scotchbond Universal Adhesive exhibited the highest μSBS, while Filtek Z250 applied with Clearfil SE Bond revealed the highest bond strength to TheraCal LC.

CONCLUSION

For all restorative materials tested in this study, TheraCal LC showed higher μSBS compared to Biodentine. For both TheraCal LC and Biodentine, the placement of GIC-based materials prior to composite resin restorations might decrease the bond strength. Composite resins applied with self-etching adhesives increased the bond strength of TheraCal LC; however, for Biodentine, application of etch-and-rinse adhesives may improve the adhesion of composite resins.

Quantitative Evaluation of MDP-Ca Salt and DCPD after Application of an MDP-based One-step Self-etching Adhesive on Enamel and Dentin

PURPOSE

To investigate the effects of an experimental 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-based one-step self-etching adhesive (EX adhesive) applied to enamel and dentin on the production of calcium salt of MDP (MDP-Ca salt) and dicalcium phosphate dehydrate (DCPD) at various periods.

MATERIALS AND METHODS

The EX adhesive was prepared. Bovine enamel and dentin reactants were prepared by varying the application period of the EX adhesive: 0.5, 1, 5, 30, 60 and 1440 min. Enamel and dentin reactants were analyzed using x-ray diffraction and solid-state phosphorus-31 nuclear magnetic resonance (31P NMR). Curvefitting analyses of corresponding 31P NMR spectra were performed.

RESULTS

Enamel and dentin developed several types of MDP-Ca salts and DCPDs with amorphous and crystalline phases throughout the application period. The predominant molecular species of MDP-Ca salt was determined as the monocalcium salt of the MDP monomer. Dentin showed a faster production rate and greater produced amounts of MDP-Ca salt than did enamel, since enamel showed a knee-point in the production rate of the MDP-Ca salt at the application period of 5 min. In contrast, enamel developed greater amounts of DCPD than did dentin and two types of DCPDs with different crystalline phases at application periods > 30 min. The amounts of MDP-Ca salt developed during the 30-s application of the EX adhesive on enamel and dentin were 7.3 times and 21.2 times greater than DCPD, respectively.

CONCLUSION

The MDP-based one-step adhesive yielded several types of MDP-Ca salts and DCPD with an amorphous phase during the 30-s application period on enamel and dentin.

Osseointegration of chemically modified sandblasted and acid-etched titanium implant surface in diabetic rats: a histological and scanning electron microscopy study

INTRODUCTION

The aim of this study is to assess the osseointegration of different dental implants surfaces in diabetic rats.

MATERIALS AND METHODS

In this study, were used 56 male Wistar rats, average weight of 300-350 g. Diabetes was induced by a single intraperitoneal injection of Streptozotocin. The glucose levels and weight of rats were periodically evaluated. After the diabetes mellitus is confirmed, the sandblasted, large-grit, acid-etched (SLA) and SLActive endosseous dental implants (TAG dental implants, TAG Medical, Israel), made of titanium alloy, Ti-6Al-4V, 1 mm diameter and 3 mm in length were inserted in the distal metaphysis of the left femur.

RESULTS

Diabetic rats have naturally lower number of bone cells and bone-implant contact (BIC%) than healthy rats when using the SLA implant, but when using SLActive implant, diabetic and healthy rats have the same numbers.

CONCLUSIONS

The use of the SLActive surface resulted in positive effects in healthy and especially in diabetic animals, which demonstrate that could improve the osseointegration progress in humans with diabetes.

Development of a Self-etch Adhesive for Resin-modified Glass Ionomers

The favorable self-adhesiveness of resin-modified glass ionomers (RMGIs) might be even further improved if the time-consuming and technically sensitive etch-and-rinse pre-treatment step with polyalkenoic acids could be avoided. We undertook this study to assess the effectiveness of an experimental self-etch adhesive for RMGIs that does not need to be rinsed off. Ultrastructural analysis and micro-tensile bond strength testing to enamel and dentin of a RMGI restorative material and a RMGI adhesive were performed after 4 different surface pre-treatments: no conditioning; 25% polyalkenoic acid; an experimental self-etch adhesive; and 37.5% phosphoric acid followed by the experimental self-etch adhesive. The use of an experimental self-etch adhesive increased the bond strength of RMGIs, especially after an additional conditioning step. Interfacial analysis showed the formation of a thin hydroxyapatite-containing hybrid layer. The self-etch technique enhances the user-friendliness of RMGIs and lowers their technique-sensitivity, while maintaining desirable characteristics of the conventional etch-and-rinse approach with polyalkenoic acids.

Influence of Pre-etching Times on Fatigue Strength of Self-etch Adhesives to Enamel

PURPOSE

To use shear bond strength (SBS) and shear fatigue strength (SFS) testing to determine the influence of phosphoric acid pre-etching times prior to application of self-etch adhesives on enamel bonding.

MATERIALS AND METHODS

Two single-step self-etch universal adhesives (Prime&Bond Elect and Scotchbond Universal), a conventional single-step self-etch adhesive (G-ӕnial Bond), and a conventional two-step self-etch adhesive (OptiBond XTR) were used. The SBS and SFS were obtained with phosphoric acid pre-etching for 3, 10, or 15 s prior to application of the adhesives, and without pre-etching (0 s) as a control. A staircase method was used to determine the SFS with 10 Hz frequency for 50,000 cycles or until failure occurred. The mean demineralization depth for each treated enamel surface was also measured using a profilometer.

RESULTS

For all the adhesives, the groups with pre-etching showed significantly higher SBS and SFS than groups without pre-etching. However, there was no significant difference in SBS and SFS among groups with > 3 s of preetching. In addition, although the groups with pre-etching showed significantly deeper demineralization depths than groups without pre-etching, there was no significant difference in depth among groups with > 3 s of pre-etching.

CONCLUSION

Three seconds of phosphoric acid pre-etching prior to application of self-etch adhesive can enhance enamel bonding effectiveness.

Resin-dentin Bond Stability of Experimental 4-META-based Etch-and-rinse Adhesives Solvated by Ethanol or Acetone

PURPOSE

To investigate the influence of 4-META concentration and type of solvent on the degree of conversion (DC%) and resin-dentin bond stability of experimental etch-and-rinse adhesives.

MATERIALS AND METHODS

Four different concentrations of 4-META (12 wt%, 20 wt%, 30 wt%, 40 wt%) were added to a model adhesive system consisting of TEG-DMA (25 wt%), UDMA (20 wt%), HEMA (30 wt%), water (4 wt%), camphorquinone (0.5 wt%), and tertiary amine (0.5 wt%) dissolved in 20% acetone (A12, A20, A30 and A40) or 20% ethanol (E12, E20, E30 and E40). DC% was evaluated by FT-IR spectroscopy. Human molars were wet ground until the occlusal dentin was exposed, the adhesive systems were applied after 37% phosphoric acid etching, and resin composite buildups were incrementally constructed. After storage in distilled water at 37°C for 24 h, the teeth were cut into resin-dentin beams (cross-sectional area 1 mm2). Microtensile bond strength (μTBS) was evaluated after 24 h, 6 months, and 1 year of water storage at 37°C. The failure mode was categorized as adhesive, mixed, or cohesive. Data were analyzed using ANOVA and Tukey's HSD test (α = 0.05).

RESULTS

A12 presented the lowest DC% (p < 0.05). All the other adhesive systems showed statistically similar DC% (p > 0.05). All adhesive systems maintained resin-dentin bond stability after 6 months of water storage, while only A40 and E40 maintained it after 1 year.

CONCLUSION

Irrespective of the type of organic solvent, the incorporation of high concentrations of 4-META (40 wt%) improved the resin-dentin bond stability of the experimental etch-and-rinse adhesive systems over a period of 1 year.

Tubular Occlusion Prevents Water-treeing and Through-and-Through Fluid Movement in a Single-bottle, One-step Self-etch Adhesive Model

Water entrapment occurs at resin-dentin interfaces of one-step self-etch adhesives. We hypothesized that by preventing water fluxes from dentin, any water entrapment would be attributed to incomplete removal of adhesive solvents. We tested this hypothesis by bonding to transparent carious dentin containing occluded dentinal tubules. An experimental single-bottle, one-step self-etch adhesive was applied to flat surfaces of caries-affected dentin surrounded by sound dentin, with or without pulpal pressure. Resin-dentin interfaces were examined with TEM after silver-impregnation. Although caries-affected dentin was highly porous, adhesive layers were devoid of silver deposits when tubules were occluded. Conversely, variable extents of water-treeing and water-droplets were identified from adhesive layers in bonded sound dentin. Water-treeing and water-droplet formation, being manifestations of evaporative and convective water fluxes, can be eliminated during bonding to occluded transparent carious dentin. However, the highly porous nature of this clinically relevant substrate after bonding may lead to potentially undesirable consequences.

Tubular Occlusion Optimizes Bonding of Hydrophobic Resins to Dentin

Although hydrophobic resins may be bonded to acid-etched dentin with an ethanol wet-bonding technique, the protocol is sensitive to moisture contamination when bonding is performed in deep dentin. This study tested the hypothesis that the use of oxalate or poly(glutamic) acid-modified, diluted ceramicrete (PADC) for dentinal tubule occlusion prevents fluid contamination and improves the bonding of an experimental hydrophobic adhesive to acid-etched, ethanol-dehydrated dentin. Mid-coronal and deep acid-etched moist dentin pre-treated with oxalate or PADC was dehydrated by ethanol wet-bonding and infiltrated with the experimental three-step etch-and-rinse hydrophobic adhesive under simulated pulpal pressure. Tensile bond strengths to deep dentin without pre-treatment were severely compromised. Conversely, oxalate and PADC pre-treatments reduced dentin permeability, prevented water contamination, and improved bond strengths. Minimal nanoleakage was identified within hybrid layers created in the oxalate- and PADC-pre-treated deep dentin. The use of tubular occluding agents optimized bonding of hydrophobic resins to dentin.

Influence of Different Etching Modes on Bond Strength to Enamel using Universal Adhesive Systems

INTRODUCTION

The adhesive systems and the techniques currently used are designed to provide a more effective adhesion with reduction of the protocol application. The objective of this study was to evaluate the bond strength of universal adhesive systems on enamel in different etching modes (self-etch and total etch).

MATERIALS AND METHODS

The mesial and distal halves of 52 bovine incisors, healthy, freshly extracted, were used and divided into seven experimental groups (n = 13). The enamel was treated in accordance with the following experimental conditions: FUE-Universal System - Futurabond U (VOCO) with etching; FUWE - Futurabond U (VOCO) without etching; SB-Total Etch System - Single Bond 2 (3M); SBUE-Universal System - Single Bond Universal (3M ESPE) with etching; SBUWE - Single Bond Universal (3M ESPE) without etching; CLE-Self-etch System - Clearfil SE Bond (Kuraray) was applied with etching; CLWE - Clearfil SE Bond (Kuraray) without etching. The specimens were made using the composite spectrum TPH (Dentsply) and stored in distilled water (37 ± 1°C) for 1 month. The microshear test was performed using the universal testing machine EMIC DL 2000 with the crosshead speed of 0.5 mm/minute. The bond strength values were analyzed using statistical tests (Kruskal-Wallis test and Mann-Whitney test) with Bonferroni correction.

RESULTS

There was no statistically significant difference between groups (p < 0.05), where FUE (36.83 ± 4.9 MPa) showed the highest bond strength values and SBUWE (18.40 ± 2.2 MPa) showed the lowest bond strength values. The analysis of adhesive interface revealed that most failures occurred between the interface composite resin and adhesive.

CONCLUSION

The universal adhesive system used in dental enamel varies according to the trademark, and the previous enamel etching for universal systems and the self-etch both induced greater bond strength values.

CLINICAL SIGNIFICANCE

Selective enamel etching prior to the application of a universal adhesive system is a relevant strategy for better performance bonding.

Pit and Fissure Sealant Retention Following Air Abrasion Preparation with Bioactive Glass and Aluminum Oxide Particles

PURPOSE

Alumina air abrasion is an alternative for acid-etch technique for tooth preparation before placement of a fissure sealant. The aim of this study was to compare the retention of sealants placed subsequent to air abrasion with alumina and bioactive glass (BAG) particles.

METHODS

Sixty-two 6-12 year old children were included in this study. Using a halfmouth design, the fissures were prepared using air abrasion with alumina particles on randomly assigned permanent mandibular or/and maxillary first molars on one side of the mouth (Group 1) and air abrasion with BAG on the contralateral side of the mouth (Group 2). Sealants were applied on 180 teeth, and were scored as missing, partially retained, and completely retained after three, six, nine and 12 months. Data were analyzed using Friedman and Wilcoxon tests (α=0.05).

RESULTS

Sealant retention rates in the alumina group were higher than those in the BAG group at all time periods (P<0.001).

CONCLUSIONS

Sealant retention after air abrasion with alumina particles was higher than BAG over 12 months.

An experimental in vivo procedure for the standardised assessment of sealants retention over time

AIM

The elaboration of an experimental system to obtain reproducible and comparable photographs of the occlusal surface to monitor sealants retention.

MATERIALS AND METHODS

An intraoral camera connected to a computer was used to obtain photos of the occlusal surfaces. A specific software was utilized to perform measurements on archived pictures. An experimental two-part system, consisting of a dental arch support and a camera support, connected to each other through holes and pins, was made to obtain a standardised and reproducible placement of the camera in the mouth. In the first part, to test the degree of reliability of the procedure and the percentage of image distortion, 120 first molars were sealed and for each molar ten photographs were taken, using the intraoral camera connected with the dental arch support, the camera support and the dedicated software. In the second part, 165 first molars were sealed and photographed, as above described, immediately after sealing (T0), 6 months (T1) and 1 year later (T2). With the software, the sealed areas were measured. The comparison of the selected sealed areas between T0 and T1, T0 and T2, T1 and T2 determined the percentage of sealant loss.

RESULTS

In the first part, the experimental procedure showed a reliability of 96.85%. In the second part, the difference in the rate of lost sealant between T0-T1 and T1-T2 was statistically significant (p <0.001).

STATISTICS

ANOVA analysis was made.

CONCLUSIONS

Photographs, obtained through the experimental two-part system, allowing a reproducible positioning of the intraoral camera in oral cavity, could represent a standardised and useful method to monitor sealants retention over time.

Effects of the Residues from the Endodontic Sealers on the Longevity of Esthetic Restorations

The substances used in the root canal treatment, especially sodium hypochlorite solution and oxidant agents, can negatively interfere on the bond strength of the adhesive systems to dentin and on the dental crowns fracture resistance.(1,2).

Physical Profile and Impact of a Calcium-Incorporated Implant Surface on Preosteoblastic Cell Morphologic and Differentiation Parameters: A Comparative Analysis

PURPOSE

To assess and compare topographic features and preosteoblastic cell responses of a new hydrothermally treated, calcium-incorporated surface against other commercially available implant surfaces.

MATERIALS AND METHODS

Four different surfaces were the subject of comparison in this study: machined (MC), resorbable blast media (RBM), sandblasted/large-grit/acid-etched (SLA), and calcium-incorporated SLA (Ca-SLA). Surface morphology and roughness were first characterized by scanning electron microscope (SEM) and white light interferometer, respectively. Preosteoblastic MC3T3-E1 cells were then cultured on the titanium surfaces. Cell morphology was observed at 24 hours, 48 hours, 7 days, and 15 days by SEM; differentiation was assessed at 7, 11, and 15 days by assaying alkaline phosphatase (ALP) activity and osteocalcin (OCN) levels.

RESULTS

Surface characterization revealed nanotopographic features on Ca-SLA. At topographic analysis, SLA and Ca-SLA showed similar roughness values. Significant differences in cell differentiation parameters were found only at 15 days between the SLA surfaces (both Ca-incorporated and nonincorporated) and MC.

CONCLUSION

Collectively, this study demonstrated that hydrothermal treatment determines the formation of nanotopography without altering the SLA microtopography. Moreover, Ca-SLA and SLA induce MC3T3-E1 cell differentiation at comparable levels.

Selective Acid Etching Improves the Bond Strength of Universal Adhesive to Sound and Demineralized Enamel of Primary Teeth

PURPOSE

To evaluate the influence of enamel condition and etching strategy on bond strength of a universal adhesive in primary teeth.

MATERIALS AND METHODS

Thirty-six primary molars were randomly assigned to six groups (n = 6) according to the enamel condition (sound [S] and demineralized [DEM]/cariogenic challenge by pH cycling prior to restorative procedures) and adhesive system (Scotchbond Universal Adhesive [SBU]) used in either etch-and-rinse (ER) or selfetching (SE) mode, with Clearfil SE Bond as the self-etching control. The adhesives were applied to flat enamel surfaces and composite cylinders (0.72 mm2) were built up. After 24-h storage in water, specimens were subjected to the microshear test. Bond strength (MPa) data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α = 0.05).

RESULTS

Significant differences were found considering the factors adhesive system (p = 0.003) and enamel condition (p = 0.001). Demineralized enamel negatively affected the bond strength, with μSBS values approximately 50% lower than those obtained for sound enamel. SBU performed better in etch-and-rinse mode, and the bond strength found for SBU applied in self-etching mode was similar to that of CSE.

CONCLUSIONS

Enamel etching with phosphoric acid improves the bond strength of a universal adhesive system to primary enamel. Demineralized primary enamel results in lower bond strength.

Influence of Surface Conditioning Protocols on Reparability of CAD/CAM Zirconia-reinforced Lithium Silicate Ceramic

PURPOSE

To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic.

MATERIALS AND METHODS

Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric EvoCeram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p < 0.05).

RESULTS

The highest microtensile repair bond strength for Vita Suprinity was reported in group CO (33.1 ± 2.4 MPa) and the lowest in group HF (27.4 ± 4.4 MPa). Regarding IPS e.max CAD, group CO showed the highest (30.5 ± 4.9 MPa) and HF the lowest microtensile bond strength (22.4 ± 5.7 MPa). Groups HF, HF-H, and CO showed statistically significant differences in terms of all ceramic types used (p < 0.05). The control group showed exclusively adhesive failures, while in HF, HF-H, and CO groups, mixed failures were predominant.

CONCLUSIONS

Repair bond strength to zirconia-reinforced lithium silicate ceramics and lithium-disilicate glass ceramic could be improved when ceramic surfaces are sandblasted with CoJet sand followed by silanization.

Effects of Different Radiation Doses on the Bond Strengths of Two Different Adhesive Systems to Enamel and Dentin

PURPOSE

To evaluate the effects of three different radiation doses on the bond strengths of two different adhesive systems to enamel and dentin.

MATERIALS AND METHODS

Eighty human third molars were randomly divided into four groups (n = 20) according to the radiation dose (control/no radiation, 20 Gy, 40 Gy, and 70 Gy). The teeth were sagittally sectioned into three slices: one mesial and one distal section containing enamel and one middle section containing dentin. The sections were then placed in the enamel and dentin groups, which were further divided into two subgroups (n = 10) according to the adhesive used. Three restorations were performed in each tooth (one per section) using Adper Single Bond 2 (3M ESPE) or Universal Single Bond (3M ESPE) adhesive system and Filtek Z350 XT (3M ESPE) resin composite and subjected to the microshear bond test. Data were analyzed using a two-way ANOVA followed by Tukey's test. Failure modes were examined under a stereoscopic loupe.

RESULTS

Radiotherapy did not affect the bond strengths of the adhesives to either enamel or dentin. In dentin, the Universal Single Bond adhesive system showed higher bond strength values when compared with the Adper Single Bond adhesive system. More adhesive failures were observed in the enamel for all radiation doses and adhesives.

CONCLUSION

Radiotherapy did not influence the bond strength to enamel or dentin, irrespective of the adhesive or radiation dose used.

Resonance Frequency Analysis of Thermal Acid-Etched, Hydrophilic Implants During First 3 Months of Healing and Osseointegration in an Early-Loading Protocol

PURPOSE

Safe loading of dental implants requires an optimal osseointegration. This osseointegration process during healing could be analyzed by resonance frequency analysis (RFA). The purpose of the study was to evaluate RFA changes during healing in splinted, early-loaded, thermal acid-etched, hydrophilic implants over time.

MATERIALS AND METHODS

Patients received a minimum of two implants: an implant with the prosthetic abutment connection at the crestal bone level (bone level) and one with the prosthetic abutment connection at a 2.5-mm supracrestal site (tissue level). Implant stability was measured at weeks 0, 2, 3, and 12 using the Osstell device.

RESULTS

Seventy-six implants were placed in 32 patients. By week 2, early-loaded tissue-level implants showed a significant drop in mean ± standard deviation (SD) implant stability quotient (ISQ) values of 2.2 ± 3.6 (P < .001). Changes in ISQ values were significant between weeks 3 and 12 and also between weeks 0 and 12, with mean differences of 4.2 (P < .001) and 2.8 (P < .001), respectively. Early-loaded bone-level implants show a significant change in ISQ of 2.3 ± 3.7 at week 2 (P < .01) and -1.3 ± 4.7 at week 12 when compared to an ISQ value of 2.9 ± 4.9 at week 3 (P < .01). Bone-level implants achieved higher ISQ values compared with tissue-level implants at weeks 0, 2, 3, and 12, with mean differences being 3.8 ± 5.5 (P < .01), 3.8 ± 6.1 (P < .01), 3.7 ± 6.7 (P < .01), and 2.3 ± 5.8 (P < .05), respectively.

CONCLUSION

This study found a significant dip in ISQ values, with the lowest point seen at week 2. ISQ values remained higher in bone-level implants throughout the process of healing and osseointegration.

Five-year Effects of Chlorhexidine on the In Vitro Durability of Resin/Dentin Interfaces

PURPOSE

To evaluate the effect of an acid containing 2% chlorhexidine (Ac/CHX) or a 2% CHX aqueous solution (Aq/CHX) on the immediate and 5-year bonding properties of resin/dentin interfaces produced by two adhesives. The presence of CHX in these interfaces was also evaluated under micro-Raman spectroscopy.

MATERIALS AND METHODS

Forty-two molars were ground to expose a flat dentin surface. In the control group, the surfaces were etched with conventional phosphoric acid, and Prime&Bond NT (PB) and Adper Single Bond 2 (SB) were applied. In Ac/CHX, an acid containing 2% CHX was applied after adhesive application. In the Aq/CHX group, an aqueous solution of 2% CHX was applied for 60 s after etching. After placing the restoration, specimens were prepared and tested using the microtensile bond strength test (μTBS, 0.5 mm/min) immediately or after 5 years. For nanoleakage (NL), specimens at each period were immersed in silver nitrate solution and examined by EDX-SEM. In addition, specimens at each period underwent examination for CHX using micro-Raman spectroscopy. Data were submitted to appropriate statistical analysis (a=0.05).

RESULTS

After 5 years, NL was more pronounced in the control than in the Ac/CHX or Aq/CHX (p<0.001). Significant reductions in the μTBS were observed for all groups; however, they were more pronounced for the control (p<0.001). CHX was still present in the hybrid layers Ac/CHX or Aq/CHX groups after 5 years.

CONCLUSION

The use of a 2% chlorhexidine-containing acid or the application of an aqueous CHX primer may increase the long-term stability of resin/dentin interfaces.

Self-adhesive Luting of Partial Ceramic Crowns: Selective Enamel Etching Leads to Higher Survival after 6.5 Years In Vivo

PURPOSE

To investigate the influence of selective enamel etching on long-term clinical performance of partial ceramic crowns (PCCs) luted with a self-adhesive luting material (RXU: RelyX Unicem).

MATERIALS AND METHODS

At baseline, 34 patients received the intended treatment: two PCCs (Vita Mark II; Cerec 3D) for the restoration of extended lesions with multiple-cusp coverage were placed in a split-mouth design with a self-adhesive luting material, one without (RXU) and one with selective enamel etching (RXU+E). Patients were evaluated clinically (modified USPHS criteria) at baseline and up to 6.5 years (70 to 88 months). The chi-square test was used for statistical analyses (α=0.05). Clinical survival of all restorations (n=68) after 6.5 years was evaluated by Kaplan-Meier analysis.

RESULTS

After 6.5 years, 18 patients (9 male, 9 female; median age 41, range 25 to 59 years) with 36 RXU and RXU+E restorations were available for clinical assessment (patient recall rate: 53%), with 13 RXU and 14 RXU+E PCCs placed in molars and 5 RXU and 4 RXU+E PCCs in premolars. Clinically, no statistically significant differences between the luting procedures were detected. Both RXU and RXU+E revealed significant changes over time with respect to marginal adaptation (significant deterioration) and marginal discoloration (significant increase). RXU revealed no cases of postoperative hypersensitivity and RXU+E only did so at baseline (n=5). Kaplan-Meier analysis showed a cumulative survival for RXU of 60% and for RXU+E of 82%, indicating a significantly higher survival rate for RXU+E.

CONCLUSION

Clinically, RXU and RXU+E perform similarly. In PCC restorations with multiple-cusp coverage, lack of retention due to adhesive preparation, and little dentin available for adhesion caused by extensive core buildups or cavity linings, selective enamel etching is recommended.

Intratubular penetration in post cementing: A comparative study between a total etching system and a self-etching cement

PURPOSE

To analyze the penetration depth and percentage perimeter with penetration of two fiber post cementing systems using confocal laser scanning microscopy (CLSM).

METHODS

20 maxillary incisors were shaped with the Mtwo system and filled using lateral condensation and TopSeal mixed with fluorescein. Fiber posts were cemented. The samples were divided into two groups of 10 teeth each, according to the post cementing technique used: Prime&Bond NT combined with Rebilda DC using a total dentin etching technique (Group 1); or BisCem a self-adhesive cement (Group 2). Rhodamine B was incorporated in the adhesive systems. Cross-sections were prepared, with the selection of three sections (coronal, middle and apical thirds). CLSM was used to measure the percentage perimeter of the root canal showing penetration of the endodontic cement and of the adhesive system in the dentin tubules, together with the maximum penetration depth. The nonparametric Mann-Whitney U-test was used to compare the data referred to each of the three tooth sections between the two study groups. The Friedman test was used to compare the variables by coronal, middle and apical thirds within each group.

RESULTS

Greater penetration was recorded with the BisCem system in all thirds, with statistically significant differences in the case of the middle and apical thirds (P = 0.001). The percentage perimeter with penetration was also greater in all thirds with the BisCem system, though without significant differences between the two groups. Penetration depth and percentage were found to decrease in the coronal to apical direction in both groups.

[Evaluation of the effect of one-step self etching adhesives applied in pit and fissure sealing]

PURPOSE

To observe the effect of three one-step self etching adhesive systems used in fit and fissure sealant and explore the feasibility of application in caries prevention in school.

METHODS

Seven hundred and twenty completely erupted mandibular first molars in 360 children aged 7 to 9 years old were chosen. The split-mouth design was used to select one side as the experimental group, divided into A1(Easy One Adper), B1(Adper Easy One), and C1(iBond SE).The contra lateral teeth served as A2,B2 and C2 groups (phosphoric acid). The retention and caries status were regularly reviewed .The clinical effect of the two groups was compared using SPSS19.0 software package for Chi - square test.

RESULTS

At 3 and 6 months, pit and fissure sealant retention rate in A1 and A2, B1 and B2,C1 and C2 group had no significant difference. At 12 months, sealant retention in A1 and B1 group was significantly lower than A2 and B2 group (P<0.05). No significant difference was found between C1 and C2 groups (P>0.05). At 24 months, sealant retention rate in A1, B1 and C1 group was significantly lower than A2, B2 and C2 group (P<0.05). The caries rate in A1and A2, B1 and B2, C1 and C2 group had no significant difference during different follow-up time (P>0.05).

CONCLUSIONS

The clinical anticariogenic effect of three kinds of one-step etching adhesives and phosphoric acid etching sealant was similar .One-step self etching adhesive system was recommended for pit and fissure sealant to improve the students' oral health. The long-term retention rate of one-step self etching adhesive system was lower than the phosphoric acid method to long term observation is needed.

Shear Bond Strength and Microleakage of a New Self-etching/Self-adhesive Pit and Fissure Sealant

PURPOSE

To evaluate shear bond strength and microleakage of a new self-etching/self-adhesive fissure sealant on prismless enamel compared with conventional fissure sealing.

MATERIALS AND METHODS

A total of 90 extracted third molars were assigned to 3 main groups: group 1: self-etching/self-adhesive sealant, without acid etching; group 2: self-etching/self-adhesive sealant, with prior acid etching; group 3: conventional fissure sealing (control group). After specimen preparation, each group was divided into 3 subgroups according to storage time (1-day water storage, 3-month water storage, and 1-day water storage followed by 5000x thermocycling). The shear bond strength was determined with a universal testing machine, according to ISO standard 29022. Afterwards, the failure mode was analyzed. An additional 24 third molars were used for microleakage assessment. The fissure pattern was sealed in strict accordance with the manufacturers' instructions. After thermocycling, the dye penetration was examined. Data were analyzed using the Mann-Whitney U-Test at a significance level of 0.05.

RESULTS

The shear bond strength of the self-etching/self-adhesive fissure sealant without prior acid etching was significantly lower (4.3 MPa) than that of the self-etching/self-adhesive fissure sealant with prior acid etching (17.1 MPa) and the conventional fissure sealing (19.1 MPa). Microleakage was significantly lower in the control group (1.1%) and in the group with the self-etching/self-adhesive sealant with prior acid etching (0.8%) compared to the group that used the self-etching/self-adhesive material alone (49.4%).

CONCLUSION

The self-etching/self-adhesive fissure sealant can be recommended for clinical use when enamel is etched with phosphoric acid. The self-etching/self-adhesive sealant without prior acid etching showed significantly inferior results.

Transenamel and Transdentinal Penetration of H2O2 in Restored Bovine Teeth

PURPOSE

To quantify hydrogen peroxide (H2O2) penetration into restored bovine teeth subjected to whitening treatment.

MATERIALS AND METHODS

Seventy-five enamel/dentin disks were divided into 5 groups (n = 15): intact disks (G1); cavity preparation only (G2); conventional adhesive system and composite resin (G3); resin-modified glass-ionomer cement (G4); and self-etching adhesive only (G5). After 24 h, the disks were placed into artificial pulp chambers containing an acetate buffer solution, and the first whitening session was performed using a 35% H2O2 (hydrogen peroxide) product. The disks were submitted to 10,000 thermal cycles and then stored for 1 year in deionized water. After this period, a second whitening session was performed. After each whitening procedure, the buffer solutions were analyzed for optical density in a spectrophotometer to assess the amount of H2O2 that had diffused. ANOVA and Tukey's test were used to compare the different groups and a Student's t-test was used to compare the different times (p ≤ 0.05).

RESULTS

Prior to aging, group 2 had the highest penetration of H2O2; the other groups showed similar, lower penetration. After thermocycling and aging, all groups showed a significant increase in H2O2 penetration. The greatest penetration of H2O2 into the pulp chamber was found in groups 2 and 5.

CONCLUSION

Aged restorations allowed greater H2O2 permeation through the tooth structure.

Zirconia Surface Treatments for Resin Bonding

PURPOSE

To evaluate the bond strength of resin to zirconia treated with different surface conditioning methods.

MATERIALS AND METHODS

Sintered zirconia was surface treated to create 7 groups. Ceramic liner (L) was fired onto three groups of zirconia and subsequently received the following treatments: hydrofluoric acid etching (L/ HFE), alumina particle abrasion (L/APA), and alumina particle abrasion with hydrofluoric acid etching (L/APAHFE). All three groups were silane treated immediately prior to bonding. Two other zirconia groups received alumina particle abrasion with and without silane coupling (AP-S and AP). Another group underwent selective infiltration etching, in which the specimens received porcelain powder firing, ultrasonic etching with HF for 15 min, then rinsing under running water for 15 min, followed by silane treatment (SIE). The control group was zirconia as-sintered (ZAS). Twenty composite resin cylinders were luted to each group with a resin cement. Each group was divided into two subgroups (n=10) and subjected to 2 storage conditions: 24 h water storage or 21 days with 6000 thermocycles between 5°C and 55°C. Shear bond strength testing (SBS) was performed, followed by statistical analysis of the results using one-way ANOVA (p < 0.05).

RESULTS

After 21 days of thermocycling, AP and ZAS groups spontaneously debonded prior to testing. The remaining groups showed a decrease in mean shear bond strength between 11.7% and 58.5% after thermocycling, except the L/HFE group, which increased by 11.7%. L/HFE showed the highest bond strength at both test intervals, and at 21 days was significantly higher than that of the AP-S and L/APA-HFE groups, which in turn were higher than that of the L/APA group, which was higher than that of the SIE group (p < 0.05).

CONCLUSION

The etched, fired ceramic liner with silane treatment provided the strongest and most durable bond under the conditions tested. Alumina particle abrasion degraded the durability of the ceramic liner. Alumina particle abrasion, as-sintered zirconia, and SIE did not provide durable bond strengths.

Short- and Long-term Evaluation of Dentin-Resin Interfaces Formed by Etch-and-Rinse Adhesives on Plasma-treated Dentin

PURPOSE

To investigate the influence of atmospheric pressure plasma (APP) treatment on the microtensile dentin bond strength of two etch-and-rinse adhesive systems, after one week and one year of water storage, and additionally to observe the micromorphology of resin/dentin interfaces under scanning electronic microscopy (SEM).

MATERIALS AND METHODS

The occlusal enamel was removed from third human molars to expose a flat dentin surface. The teeth were then randomly divided into six groups (n = 7), according to two adhesives (Optibond FL and XP-Bond) and three APP treatments (untreated dentin [control], APP application before or after acid etching). After performing the composite resin buildup on bonded dentin, the teeth were sectioned perpendicularly to the bonded interface to obtain beam-shaped specimens (cross-sectional area of ~0.9 mm2). The specimens were tested in tension until failure after one week and one year of water storage (1.0 mm/min rate). Bond strength data were analyzed by three-way ANOVA and Tukey's post-hoc test (α = 0.05%). Bonded beam specimens from each tooth were also prepared for interfacial SEM investigation.

RESULTS

At one week, APP treatment applied after acid etching increased the dentin bond strength for XP Bond, while no effect was observed for Optibond FL. After one year, the bond strength of XP Bond decreased in groups where APP was applied after etching. The evaluation time did not influence the bond strength for Optibond FL.

CONCLUSION

One-year evaluation did not show any sign of degradation of interfacial structures in any group. Application of APP to etched dentin combined with a two-step etch-and-rinse adhesive significantly increased bond strength at one week, but the effect was not stable after one year and was adhesive dependent.

A Guided, Conservative Approach for the Management of Localized Mandibular Anterior Tooth Wear

The successful management of the worn mandibular anterior dentition may present an awkward challenge to the dental operator. The purpose of this article is to describe a case report illustrating the use of a guided, three-dimensional protocol for the ultra-conservative and predictable restoration of the worn lower anterior dentition using direct resin composite. This technique utilizes information based on established biomechanical and occlusal principles to fabricate a diagnostic wax-up, which is duplicated in dental stone. This is used to prepare a vacuum-formed modified stent, assisting the clinician to place directly bonded resin composite restorations to restore the worn lower anterior dentition. The technique, described in 2012 and referred to as 'injection moulding' has the potential to offer optimal form, function and an aesthetic outcome in an efficient manner. CPD/Clinical Relevance: This article aims to describe an alternative technique to simplify the processes involved with restoration of worn lower anterior teeth.

Porcelain surface conditioning protocols and shear bond strength of orthodontic brackets

AIM

The objective of the present study was to determine which of six bonding protocols yielded a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets to CAD/CAM lithium disilicate porcelain restorations. A secondary aim was to determine which bonding protocol produced the least surface damage at debond.

METHODS

Sixty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular first molar using a CEREC CAD/CAM machine. The samples were split into six test groups, each of which received different mechanical/chemical pretreatment protocols to roughen the porcelain surface prior to bonding a molar orthodontic attachment. Shear bond strength testing was conducted using an Instron machine. The mean, maximum, minimal, and standard deviation SBS values for each sample group including an enamel control were calculated. A t-test was used to evaluate the statistical significance between the groups.

RESULTS

No significant differences were found in SBS values, with the exception of surface roughening with a green stone prior to HFA and silane treatment. This protocol yielded slightly higher bond strength which was statistically significant.

CONCLUSION

Chemical treatment alone with HFA/silane yielded SBS values within an acceptable clinical range to withstand forces applied by orthodontic treatment and potentially eliminates the need to mechanically roughen the ceramic surface.

Effect of bromelain and papain gel on enamel deproteinisation before orthodontic bracket bonding

AIM

To test the hypothesis that enamel surface deproteinisation with different concentrations of bromelain in association with 10% papain increases the shear bond strength (SBS) of brackets bonded with orthodontic composite and resin modified glass ionomer cement (RMGIC).

MATERIALS AND METHODS

Orthodontic brackets were attached according to the following protocols to 195 bovine incisors, which were acquired and divided into 13 groups: 1) Transbond XT (TXT) according to the manufacturer's recommendations; 2) Deproteinisation with 3% bromelain (BD) plus 10% papain and TXT; 3) 6% BD plus 10% Papain and TXT; 4) RMGIC, without enamel deproteinisation and without acid etching; 5) RMGIC, with 3% BD plus 10% papain and without acid etching; 6) RMGIC, with 6% BD plus 10% papain and without acid etching; 7) attachment using RMGIC following etching with polyacrylic acid; 8) 3% BD plus 10% papain, attachment using RMGIC and etching with polyacrylic acid; 9) 6% BD plus 10% papain, and attachment using RMGIC following etching with polyacrylic acid; 10) etching with 37% phosphoric acid and attachment using RMGIC; 11) 3% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 12) 6% BD plus 10% papain, etching with 37% phosphoric acid and attachment using RMGIC; 13) deproteinisation with 2.5% sodium hypochlorite (NaOCl), etching with polyacrylic acid and RMGIC. After bonding, the brackets were removed by a universal mechanical testing machine, which recorded shear bond strength at failure. The material remaining on the tooth was assessed using the adhesive remnant index (ARI).

RESULTS

Deproteinisation with 3% and 6% bromelain gel plus papain significantly increased the shear bond strength (p < 0.05), when acid etching was performed with phosphoric acid, followed by primer application and attachment using Transbond XT (Group 3) and when attached with RMGIC without etching. Deproteinisation with 6% bromelain gel plus papain significantly increased (p < 0.05) the ARI score only when attachment was performed using RMGIC, without etching (Group 6).

CONCLUSIONS

Deproteinisation with bromelain associated with papain in a gel increased the shear bond strength and is recommended before orthodontic bracket attachment.

Effect of a new salivary-contaminant removal method on bond strength

The study evaluated the effect of salivary-contaminant removal methods on the bond strength of resin cement to hydrofluoric acid-etched ceramic. Treatment with a new cleaning paste resulted in bond strengths not significantly different from those obtained in phosphoric acid-treated, hydrofluoric acid-treated, and uncontaminated control groups; thus the paste may be considered an alternative to phosphoric acid or hydrofluoric acid for removal of salivary contaminants.

Fracture Strength of Endodontically Treated Teeth Restored with Composite Overlays with and without Glass-fiber Reinforcement

PURPOSE

To evaluate the fracture strength and the failure mode of endodontically treated teeth restored with composite resin overlays with and without glass-fiber reinforcement.

MATERIALS AND METHODS

A total of 32 extracted molars were divided into four equal groups. In the NFR-NFRC (no foundation restoration, no fiber-reinforced composite) and NFR-FRC (no foundation restoration, fiber-reinforced composite) groups, only a 5-mm-thick composite resin layer sealed the pulp chamber floors, whereas in the FR-NFRC (foundation restoration, no fiber-reinforced composite) and FR-FRC (foundation restoration, fiber-reinforced composite) groups, a 3.0-mm foundation restoration was used. NFR-NFRC and FR-NFRC groups were restored with composite resin overlays, whereas NFR-FRC and FR-FRC groups were restored with fiber-reinforced composite resin overlays. All specimens were subjected to mechanical loading in a computer-controlled masticator and then the fracture resistance was evaluated. Differences in means were compared using two-way ANOVA and Tukey's test. The level of significance was set at ɑ = 0.05.

RESULTS

All specimens successfully completed the fatigue test. The least fracture-resistant group was NFR-FRC, exceeded by FR-NFRC, NFR-NFRC, and FR-FRC, in that order, with FR-FRC being the most fracture-resistant group. Statistically significant differences were detected between the pairs NFR-NFRC/FR-FRC (p = 0.001), NFR-FRC/FR-FRC (p = 0.001), and FR-NFRC/FR-FRC (p = 0.001). Eight vertical root fractures occurred in group FR-NFRC, six in group NFR-NFRC, four in group NFR-FRC, and none occurred in group FR-FRC.

CONCLUSIONS

Within the limitations of this in vitro study, the incorporation of glass fibers and the presence of a foundation restoration were found to increase the fracture resistance and can favorably influence the fracture mode.

Using a Dental Student Exercise on Shear Bond Testing to Both Provide Skills Practice and Demonstrate a Research Process

This article describes an exercise with junior dental students at the University of the Pacific Arthur A. Dugoni School of Dentistry designed in part to serve the requirement for dental accreditation Standard 6-3 ("Dental education programs must provide opportunities, encourage, and support student participation in research and other scholarly activities mentored by faculty"). The exercise has been conducted for seven years and has been found to provide a distinctive and important experience to the education of these dental students. The exercise has three aims. First, it is an exercise in which students practice their skills with dental bonding; second, it serves as a tool to give immediate feedback on these skills that is otherwise not possible in a real patient situation; and third, it demonstrates to the students how data from the exercise with the students as subjects can be used in a research study. The project thus serves as an innovative way to use a skill-building exercise to educate students about research at the same time.

One-year Clinical Evaluation of Resin Composite Restorations of Noncarious Cervical Lesions in Smokers

PURPOSE

To evaluate the one-year clinical performance of composite restorations in noncarious cervical lesions placed in smoking and non-smokers using a multimode adhesive system with two adhesive strategies.

MATERIALS AND METHODS

Among the selected cervical lesions, four experimental groups were formed based on the patients' smoking habit and bonding strategies with a multimode adhesive system (n = 38): G1: etchand- rinse in non-smokers; G2: selective enamel etching in non-smokers; G3: etch-and-rinse in smokers; G4: selective enamel etching in smokers. The restorations were paired, ie, each patient received at least two restorations. A nanofilled resin composite was applied and light cured incrementally in all groups by one operator. Two calibrated examiners evaluated the restorations at baseline, 6 and 12 months after placement. The modified USPHS criteria were used for evaluation. Data were analyzed using the chi-square (for associations between groups) and McNemar tests.

RESULTS

No statistically significant difference was found between groups for the criteria of retention, marginal discoloration, color match, marginal integrity, or sensitivity after 6 and 12 months. The assessments over time showed a statistically significant difference only for marginal discoloration at 12 months for groups 1, 3, and 4 when compared to baseline (p = 0.031). There were no statistical differences for any criteria evaluated among smokers and non-smokers, except for color match, where a difference was found after the baseline evaluation. Regarding the adhesive strategy, etch-and-rinse resulted in a clinical performance similar to that of selective enamel etching over 12 months.

CONCLUSION

Neither cigarette smoking habit nor adhesive strategy influenced the clinical performance of resin composite cervical restorations over the first year.

Direct Composite Restorations to Mask Intrinsic Staining: An Eighteen-Year Follow-Up

In this case example, the use of direct composite resin allowed for a relatively simple, conservative treatment that provided excellent function and aesthetics, while preserving healthy dental tissue. The importance of continued follow-up and a periodic maintenance and minor repair process will ensure longevity of the restorations, as aesthetics, and the occlusion.

Effect of adhesive materials on shear bond strength of a mineral trioxide aggregate

PURPOSE

To compare the shear bond strength (SBS) and fractography between mineral trioxide aggregate (MTA) and glass-ionomer cement (GIC) or resin composite (RC) after varying MTA setting time intervals.

METHODS

MTA was mixed and packed into standardized cavities (4 mm diameter x 3 mm depth) in acrylic blocks. RC with 37% H₃PO₄ and type 2 (etch and rinse) adhesive, or conventional GIC was bonded to the exposed MTA sample surfaces after 10-minute, 24-hour, 72-hour and 30-day MTA setting intervals (n = 10/group, eight groups). Samples were stored (37°C, 24 hours, 100% humidity) before SBS testing and statistical analysis (ANOVA, Tukey LSD, P < 0.05). Fractography was undertaken using stereomicroscopy for all samples and three random samples/group by using SEM.

RESULTS

Significant differences between all groups were found (P= 0.002). SBS of RC:MTA (Max 5.09 ± 1.79 MPa) was higher than the SBS of GIC:MTA (Max 3.74 ± 0.70 MPa) in 24-hour, 72-hour and 30-day groups except in the 10-minute MTA setting time groups, where SBS of GIC:MTA was higher. There was a significant effect of time on SBS of RC: MTA (P = 0.008) and no effect on SBS of GIC:MTA (P = 3.00). Fractography revealed mixed (adhesive/cohesive) failures in all groups; in RC:MTA groups there was a decrease in adhesive failure with time in contrast to the GIC:MTA groups.

[Influence of different acid etching modes on bond strengths to non-carious sclerotic dentin]

PURPOSE

To evaluate the effect of different acid etching modes on bond strength between composite resin and non-carious sclerotic dentin, and to provide references for clinical application.

MOTHODS

Thirty premolars with naturally-occurring non-carious cervical lesions were divided into 2 groups based on self-etch adhesive system AdperTM Easy one (AEO) and total-etch adhesive system AdperTM Single Bond2 (ASB2). Each group was further divided into 3 subgroups (ASB21, ASB22, ASB23, AEO1, AEO2, AEO3) and subjected to the following processing: ASB21 subgroup was etched for 15 s with 35% phosphoric acid and coated with binder for 15 s; ASB22 subgroup was etched for 30 s with 35% phosphoric acid and coated with binder for 15 s; ASB23 subgroup was etched for 15 s with 35% phosphoric acid and coated with binder for 30 s; AEO1 subgroup was only etched with binder for 20 s; AEO2 subgroup was etched with binder for 40 s; AEO3 subgroup was etched for 15 s with 35% phosphoric acid and coated with binder for 20 s. The samples were restored with composite resin; 24 h after saved in distilled water at room temperature, the teeth were cut into dumbbell-shaped specimens with surface areas of approximately 1.0 mm2. The microtensile bond strength (μTBS) was detected and evaluated by one-way ANOVA and SNK-q test using SPSS 17.0 software package.

RESULTS

μTBS was given in MPa: AEO3>ASB22>ASB23>ASB21>AEO2>AEO1, AEO3 resulted in statistically highest bond strength and AEO1 had the lowest bond strength (P<0.05), ASB22 acquired bond strength just lower than AEO3 (P<0.05).

CONCLUSIONS

Use of total-etch adhesive system increasing the etching time of phosphoric time can enhance bond strength. For self-etch adhesive system,both duplicated the time of adhesive treatment and use of phosphoric acid can improve the bond strength. Use of phosphoric acid to etch for 15 s and coated with self-etch adhesive system for 20 s achieved the highest bond strength. In either self-etch or total-etch adhesive system, use of phosphoric acid to etch for 15 s and coated with self-etch adhesive system for 20 s achieved optimal bond strength, there was the lowest bond strength when the self-etch adhesive system used as recommended time.

Comparing different enamel pretreatment options for resin-infiltration of natural non-cavitated carious lesions

PURPOSE

To compare two different enamel pretreatments and their effect on the efficiency of penetration of a one-component adhesive into natural carious lesions.

METHODS

Eight extracted human molars and premolars with non-cavitated interproximal lesions were selected. ICDAS code 1-2 was assessed by visual, microscopic, X-ray and Diagnocam record analysis. Samples were cut vertically across the demineralization to obtain two symmetrical lesions, (n=16). After isolating the cut surfaces with nail varnish, paired lesion halves' surfaces were pretreated with two different techniques: Group 1: surfaces were firstly abraded with fine diamond-coated metallic strips (Steelcarbo) and then etched with 37% H₃PO₄ acid (Omni-etch, 120 seconds); Group 2: lesion surfaces were etched with 15% HCl acid (Icon-etch, 120 seconds). All teeth were stained with rhodamine isothiocyanate (RITC) solution (12 hours) and subsequently stored in dry chamber (3 hours). All samples were penetrated with a one-component adhesive (Scotchbond Universal) for 180 seconds and coated with a thin layer of flowable composite (Tetric Flow). After light curing, un- encapsulated dye was bleached by immersion in 30% hydogen peroxide for 12 hours at 37°C. Remaining lesion pores were stained with sodium fluorescein solution. Thin cuts of the teeth were observed with confocal microscopy and computer image analysis was performed (ImageJ). The percentage of penetration (area of resin penetration/area of total demineralization x100) was calculated.

RESULTS

Pretreatment with fine aluminum oxide-coated metallic strip followed by 37% H₃PO₄ acid showed a larger infiltration area (51.7% ± 12.2) in almost all samples compared to pretreatment with 15% HCl acid alone (22.1% ± 13.2). Statistical analysis using t-test showed a significant difference between the two groups (P = 0.011).

Effect of Matrix Metalloproteinase-inhibiting Solutions and Aging Methods on Dentin Bond Strength

PURPOSE

This study examined the effects of matrix metalloproteinase-inhibiting solutions and aging methods on the bond strength between resin composite and human dentin.

MATERIALS AND METHODS

Crown segments of 105 human non-carious molars were bonded using simulated pulpal pressure at 20 cm water pressure. The teeth were randomly split into 5 groups according to the solution applied: CG (control, no solution), CHX (0.2% chlorhexidine), EPE (10% ethanolic propolis extract), APE (aqueous propolis extract), and E (70% ethanol). Each solution was left on the acid-etched dentin for 1 min. Adper Single Bond 2 and resin composite (Filtek Z350 XT) were applied to all specimens. The 5 groups were subdivided according to the aging method: SI (sectioned immediately); S (storage in artificial saliva for 6 months); and T (thermomechanical aging with 240,000 mechanical cycles and 1000 thermal cycles). Specimens were sectioned into sticks and subjected to microtensile testing. Bond strength data were analyzed by two-factor ANOVA followed by a post-hoc Tukey's test (α=0.05).

RESULTS

For the factor "solution", there was no significant difference among the groups (p=0.32). For the factor "aging method", significant differences were found (p<0.001), with the following mean bond strengths (MPa): SI: 31.1; S: 24.4; T: 26.8.

CONCLUSIONS

The use of matrix metalloproteinase-inhibiting solutions on dentin as an adjunct to the application of an etch-and-rinse adhesive does not prevent the loss of bond strength after aging. Nevertheless, these solutions have no adverse effect on adhesion to tooth structure.

Effect of Hydrofluoric Acid Concentration on Resin Adhesion to a Feldspathic Ceramic

PURPOSE

To evaluate the effect of different concentrations of hydrofluoric acid (HF) on the contact angle and the resin bond strength durability to feldspathic ceramic.

MATERIALS AND METHODS

To evaluate the contact angles of distilled water on etched feldspathic ceramic, 25 specimens (12×10×2.4 mm) of VitaBlocks Mark II were used, divided into 5 groups (n=5): one unconditioned control (UC) group with no ceramic surface treatment, and 4 other groups that were etched for 60 s with different concentrations of HF: 1% (HF1), 3% (HF3), 5% (HF5) and 10% (HF10). The bond testing utilized 40 ceramic blocks (12×10×4 mm) that were fabricated and subjected to the same surface treatments as previously mentioned (excluding the control). The etched surfaces were silanized and resin cement was applied. After 24 h, the blocks were sectioned to produce bar specimens that were divided into two groups, non-aged (immediate testing) and aged (storage for 230 days+12,000 thermocycles at 5°C and 55°C), and subjected to microtensile testing (μTBS). Micromorphogical analysis of the treated surfaces was also performed (atomic force and scanning electron microscopy). One-way ANOVA and Tukey's tests were applied for data analysis.

RESULTS

UC had the highest contact angle (61.4°), whereas HF10 showed the lowest contact angle (17.5°). In non-aged conditions, different acids promoted statistically similar bond strengths (14.2 to 15.7 MPa) (p>0.05); in terms of bond durability, only the bond strength of the HF1 group presented a statistically significant decrease comparing before and after aging (14.5 to 10.2 MPa).

CONCLUSION

When etched with 3%, 5%, or 10% hydrofluoric acid, the ceramic tested showed stable resin adhesion after long-term aging.

Resin Infiltration for Aesthetic Improvement of Mild to Moderate Fluorosis: A Six-month Follow-up Case Report

PURPOSE

To determine whether fluorosed areas of teeth can be successfully treated with resin infiltration and whether the results are long lasting.

MATERIALS AND METHODS

For the present case of mild to moderate dental fluorosis, the microinvasive resin infiltration technique was chosen, following suboptimal results of in-office vital tooth bleaching to improve the aesthetic appearance of the affected teeth.

RESULTS

Six months after treatment, the white opaque and brown discolourations remain masked.

CONCLUSION

This case report demonstrates that resin infiltration is an agreeable option for this type of tooth discolouration, rather than choosing more invasive, conventional procedures. More studies need to be completed to determine longer-term outcomes of the technique.

Restoring Nonvital Premolars with Composite Resin Onlays: Effect of Different Fiber-reinforced Composite Layers on Marginal Adaptation and Fracture Load

PURPOSE

To evaluate the marginal adaptation and fracture load of composite resin onlays reinforced with different substructures.

MATERIALS AND METHODS

Thirty-two extracted, caries-free premolars were selected for this study and endodontically treated. Group 1 was used as the control group, and the teeth were restored only with as-manufactured composite resin overlays. Group 2 teeth were restored with composite resin overlays with 3 fiber-reinforced composite (FRC) layers placed horizontally on the bottom of the restoration. Group 3 teeth were restored with composite resin overlays with 6 fiber-reinforced composite (FRC) layers placed as in group 2. Group 4 teeth were restored with composite resin overlays and FRC placed with an anatomical design. All specimens underwent SEM evaluation of their marginal adaptation before and after thermocycling and cyclic mechanical loading. All specimens were then subjected to a fracture test, recording the value for the initial (IF) and final (FF) failure. Differences in the means were compared using matched-pairs t-tests and one-way ANOVA. The level of significance was set at α = 0.05.

RESULTS

No statistically significant difference between the four groups in terms of marginal adaptation was observed at the tooth/luting composite and luting composite/overlay interfaces before and after loading. The fracture loads of IF and FF, from most to least resistant were: group 4 (1431.8 ± 294.3 N/1710.1 ± 326.6 N), group 3 (1428.1 ± 251.4 N/1467.9 ± 242.4 N), group 2 (852.6 ± 413.5 N/1058.1 ± 251.5 N) and group 1 (899.8 ± 352.7 N/923.5 ± 318.8 N). Significant differences (p = 0.026) were observed comparing group 1 to groups 2 and 3, and group 1 to 4. Three irreparable fractures were found in group 3, four in group 2, and five in groups 1 and 4.

CONCLUSIONS

The presence or absence of reinforcement and the different configuration of the reinforcement fibers affect fracture strength but only partially the failure modality. The presence or absence of reinforcement does not alter marginal adaptation.

Shear Bond Strength of Self-etching Adhesives to Cavities Prepared by Diamond Bur or Er,Cr:YSGG Laser and Effect of Prior Acid Etching

PURPOSE

To compare and evaluate shear bond strength of self-etching adhesives bonded to cavities prepared by diamond bur or Er,Cr:YSGG laser and the effect of prior acid etching on shear bond strength.

MATERIALS AND METHODS

Ninety-six caries-free human premolars were selected and divided into 2 groups depending on mode of cavity preparation (48 teeth each). Cavities were prepared with Er,Cr:YSGG laser in group 1 and diamond burs in an air-turbine handpiece in group 2. Groups 1 and 2 were further subdivided into three subgroups of 8 teeth each, which were bonded with sixth- or seventh-generation adhesives with or without prior acid etching, followed by restoration of all samples with APX Flow. These samples were subjected to shear bond strength testing. In addition, the surface morphology of 24 samples each from groups 1 and 2 was evaluated using SEM. Data were analyzed using the Shapiro-Wilk test, one- and two-way ANOVA, the t-test, and the least significant difference test, which showed that the data were normally distributed (p > 0.05).

RESULTS

The shear bond strength of adhesives in cavities prepared by Er,Cr:YSGG laser was significantly higher than in diamond bur-prepared cavities (p < 0.05). SEM analysis showed a smear-layer-free anfractuous surface on laser-ablated teeth, in contrast to conventional bur-prepared teeth.

CONCLUSIONS

The Er,Cr:YSGG laser-ablated surface proved to be more receptive for adhesion than those prepared by diamond bur irrespective of the bonding agent used. Seventh-generation adhesives yielded higher shear bond strength than did sixth-generation adhesives. Prior acid etching decreased the shear bond strength of self-etching adhesives.

Machined versus roughened immediately loaded and finally restored single implants inserted flapless: Preliminary 6-month data from a split- mouth randomised controlled trial

PURPOSE

To compare the outcome of immediately loaded single implants with a machined or a roughened surface.

MATERIALS AND METHODS

Fifty patients had two implant sites randomly allocated to receive flaplessplaced single Syra implants (Sweden & Martina), one with a machined and one with a roughened surface (sand-blasted with zirconia powder and acid etched), according to a split-mouth design. To be loaded immediately, implants had to be inserted with a torque superior to 50 Ncm. Implants were restored with definitive crowns in direct occlusal contact within 48 h. Patients were followed for 6 months after loading. Outcome measures were prosthetic and implant failures and complications.

RESULTS

Two machined implants and four roughened implants were not loaded immediately. Six months after loading no dropout occurred. One implant loaded late, which had a rough implant surface, failed 20 days after loading (P (McNemar test) = 0.625; difference in proportions = -0.04; 95% CI: -0.15 to 0.07). Three crowns had to be remade on machined implants and four on roughened implants (P (McNemar test) = 1.000; difference in proportions = -0.02; 95% CI: -0.12 to 0.08). Three machined and five roughened implants experienced complications (P (McNemar test) = 0.625; difference in proportions = -0.04; 95% CI: -0.15 to 0.07). There were no statistically significant differences between groups for crown and implant losses as well as complications.

CONCLUSIONS

Up to 6 months after loading both machined and roughened flapless-placed and immediately loaded single implants provided good and similar results, however, longer follow-ups are needed to evaluate the long-term prognosis of implants with different surfaces.

CAD/CAM monolithic restorations and full-mouth adhesive rehabilitation to restore a patient with a past history of bulimia: the modified three-step technique

Due to an increasing awareness about dental erosion, many clinicians would like to propose treatments even at the initial stages of the disease. However, when the loss of tooth structure is visible only to the professional eye, and it has not affected the esthetics of the smile, affected patients do not usually accept a full-mouth rehabilitation. Reducing the cost of the therapy, simplifying the clinical steps, and proposing noninvasive adhesive techniques may promote patient acceptance. In this article, the treatment of an ex-bulimic patient is illustrated. A modified approach of the three-step technique was followed. The patient completed the therapy in five short visits, including the initial one. No tooth preparation was required, no anesthesia was delivered, and the overall (clinical and laboratory) costs were kept low. At the end of the treatment, the patient was very satisfied from a biologic and functional point of view.