Warner Kalk

Biting and Chewing in Overdentures, Full Dentures, and Natural Dentitions

It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.

Effect of the cross-linking silane concentration in a novel silane system on bonding resin-composite cement

Objective. Four experimental blends of an organo-functional silane monomer with a non-functional cross-linking silane monomer (a novel silane system) were evaluated as adhesion promoters in an experiment in which a resin-composite cement was bonded to silica-coated titanium. Material and Methods. 3-Acryloyloxypropyltrimethoxysilane (as constant 1.0 vol%) was blended with 1,2-bis-(triethoxysilyl)ethane, where its concentration was 0.1, 0.2, 0.3, or 0.5 vol%. Titanium slides (n=20) were grit-blasted, silica-coated, and silanized with four experimental silane solutions, with a pre-activated silane Cimara™ (VOCO, Germany) as control. After silanization, resin-composite cement stubs (Bifix™ QM; VOCO, Germany) were photo-polymerized. The shear bond strength was measured after dry storage (24 h) or after thermo-cycling (6000 cycles between 5°C and 55°C). The resin stub failure mode was determined. Results. Statistical analysis (ANOVA) showed that type of storage (p <0.05) and concentration of cross-linker silane (p<0.005) both significantly affected the shear bond strength. The highest shear bond strength was obtained with a blend of 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.3 vol% 1,2-bis-(triethoxysilyl)ethane, 15.9 MPa (standard deviation SD 3.4 MPa) for both the thermo-cycled group and after dry storage (24 h), 14.3 MPa (SD 4.1 MPa) (n=8/group). The lowest values were obtained with Cimara™ silane 7.3 MPa (SD 2.2 MPa) in dry storage and 7.9 MPa (SD 2.0 MPa) obtained with 1.0 vol% 3-acryloyloxypropyltrimethoxysilane+0.1 vol% 1,2-bis-(triethoxysilyl)ethane. The failure type was mainly cohesive. Conclusion. A novel silane system with an optimal concentration of the cross-linking silane may produce significantly higher shear bond strength between silica-coated titanium and resin-composite cement compared to a pre-activated silane product.

An international multicenter study on the effectiveness of a denture adhesive in maxillary dentures using disposable gnathometers

No consensus has been achieved on whether denture adhesives are beneficial adjuncts in denture-wearers management. The purpose of this international multicenter study was to determine objectively the effect of a denture adhesive (Kukident) on the retention of complete maxillary dentures using disposable gnathometers. The disposable gnathometers have a decimal scale for measuring the incisal force before dislodgement (= maximum incisal force) of maxillary dentures. The intra-observer reliability, the inter-observer reliability, and the linearity of the gnathometer units of the disposable gnathometers were examined in three pilot studies. Participants of the international multicentre main study were 88 patients who had been selected for complete maxillary denture treatment. The maximum incisal force of their previous and new denture without and with adhesive was measured using disposable gnathometers. The intra- and inter-observer reliability of the disposable gnathometers was very good, and there was a linear relation between the gnathometer units. The effect of the denture adhesive on the maximum incisal force of complete maxillary dentures was statistically significant in previous as well as new dentures, being more pronounced in previous than in new dentures.

Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

OBJECTIVESnThis randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials.nnnMETHODSnA total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in combination with two adhesive resins (Ena-Bond-Enamel HFO: n=48, Clearfil SE Bond-Miris2: n=48). Enamel was selectively etched with 38% H(3)PO(4) for 30s, rinsed 30s and the corresponding adhesive resin was applied accordingly. Existing resin composite restorations in good conditions (small or big) were not removed but conditioned using silica coating (CoJet) and silanized (ESPE-Sil). Restorations were evaluated at baseline and thereafter every 6 months. Additional qualitative analysis was performed using modified USPHS criteria.nnnRESULTSnMean observation period was 41.3 months. Altogether, 12 absolute failures were observed [survival rate: 87.5%] (Kaplan-Meier). The survival rates with the two resin composites did not show significant differences [Enamel HFO: 81.2%, Miris2: 93.8%] (p>0.05). The presence of existing composite restorations on the prepared teeth did not affect the survival rate significantly (intact teeth: 100%, small restorations: 90.6%, big restorations: 82.7%) (p>0.05). Surface roughness and marginal discolouration were the main qualitative deteriorations observed until the final recall. Secondary caries and endodontic complications did not occur in any of the teeth.nnnCONCLUSIONnEarly findings of this clinical study with the two micro-hybrid composite laminate veneers showed similar survival rate and their clinical performance was not significantly influenced when bonded onto intact teeth or onto teeth with existing restorations with the protocol applied.

Randomized Clinical Trial of Indirect Resin Composite and Ceramic Veneers: Up to 3-year Follow-up

PURPOSEnThis randomized controlled split-mouth clinical trial evaluated the short-term survival rate of indirect resin composite and ceramic laminate veneers.nnnMATERIALS AND METHODSnA total of 10 patients (mean age: 48.6 years) received 46 indirect resin composite (Estenia; n = 23) and ceramic laminate veneers (IPS Empress Esthetic; n = 23) on the maxillary anterior teeth. Veneer preparations with incisal overlap were performed and existing resin composite restorations of good quality were not removed but conditioned using silica coating (CoJet) and silanization (ESPE-Sil). Enamel and dentin were etched and rinsed; adhesive resin (ExciTE) was then applied. After cementation (Variolink Veneer), restorations were evaluated at baseline and thereafter every 6 months for up to 3 years using modified USPHS criteria.nnnRESULTSnSeventeen laminate veneers were bonded onto intact teeth and 29 on teeth having existing resin composite restorations. In total, 3 failures were observed in the form of debonding (n = 1) and fracture (n = 2) in the group of resin composite laminate veneers. No significant difference was observed between the survival rates of composite and ceramic laminate veneers (Estenia: 87%, IPS Empress Esthetic: 100%; p > 0.05). The overall survival rate was 93.5% (Kaplan-Meier). Of the 43 laminate veneers, minor voids and defects were observed in 6 of the composite and 3 of the ceramic veneers. Slight staining at the margins (n = 3) and slightly rough surfaces were more frequently observed for the resin composite laminate veneers (n = 18) up to the final recall.nnnCONCLUSIONnEarly findings of this clinical trial on two veneer materials showed statistically similar survival rates. Surface quality changes were more frequent in the composite veneer material.

Effect of static and cyclic loading on ceramic laminate veneers adhered to teeth with and without aged composite restorations.

PURPOSEnExisting composite restorations on teeth are often remade prior to the cementation of fixed dental prostheses. The aim of this study was to evaluate the effect of static and cyclic loading on ceramic laminate veneers adhered to aged resin composite restorations.nnnMATERIALS AND METHODSnEighty sound maxillary incisors were collected and randomly divided into four groups: group 1: control group, no restorations; group 2: two Class III restorations; group 3: two Class IV restorations; group 4: complete composite substrate. Standard composite restorations were made using a microhybrid resin composite (Anterior Shine). Restored teeth were subjected to thermocycling (6000 cycles). Window preparations were made on the labial surface of the teeth for ceramic laminate fabrication (Empress II). Teeth were conditioned using an etch-and-rinse system. Existing composite restorations representing the aged composites were silica coated (CoJet) and silanized (ESPE-Sil). Ceramic laminates were cemented using a bis-GMA-based cement (Variolink Veneer). The specimens were randomly divided into two groups and were subjected to either static (groups 1a, 2a, 3a, 4a) or cyclic loading (groups 1b, 2b, 3b, 4b). Failure type and location after loading were classified. Data were analyzed using one-way ANOVA and Tukeys test.nnnRESULTSnSignificantly higher fracture strength was obtained in group 4 (330 ± 81 N) compared to the controls in group 1 (179 ± 120 N) (one-way ANOVA, p < 0.05). Group 1b survived a lower mean number of cyclic loads (672,820 cycles) than teeth of groups 2b to 4b (846x103 to 873x103 cycles). Failure type evaluation after the fracture test showed predominantly adhesive failures between dentin and cement, but after cyclic loading, more cohesive fractures in the ceramic were seen.nnnCONCLUSIONnCeramic laminate veneers bonded to conditioned aged composite restorations provided favorable results. Surface conditioning of existing restorations may eliminate the necessity of removing aged composite restorations.

Clinical longevity of ceramic laminate veneers bonded to teeth with and without existing composite restorations up to 40 months.

ObjectivesThis study evaluated the survival rate of ceramic laminate veneers bonded to teeth with and without existing composite restorations (ECR).Materials and methodsTwenty patients (mean age: 49.7xa0years) received 92 feldspathic ceramic laminate veneers (Shofu Vintage AL) on the maxillary teeth (intact teeth: nu2009=u200926; teeth with ECR: nu2009=u200966). Preparations with incisal overlap were made, and ECR of good quality were not removed but conditioned using silica coating (CoJet) and silanization (ESPE-Sil). Enamel and dentin were etched with 38xa0% H3PO4 for 15–30xa0s and rinsed 30xa0s; adhesive resin (Excite) was applied, and laminate veneers were then cemented (Variolink Veneer). Restorations were evaluated at baseline and thereafter every 6xa0months using modified United States Public Health Service criteria.ResultsMean observation period was 21.6xa0months. Overall, five absolute failures were encountered (fractures: nu2009=u20093; chipping: nu2009=u20091; debonding: nu2009=u20091), resulting in a survival rate of 94.6xa0% (Kaplan–Meier). Survival rates of the laminates bonded to teeth without (96xa0%) and with ECR (93.5xa0%) did not show significant differences (pu2009>u20090.05). Slight marginal defects (16 of 87 laminates) and slight marginal discoloration at the margins were noted (12 of 87 laminates) until the final recall. Secondary caries and endodontic complications were not detected in any of the teeth.ConclusionThe clinical survival of ceramic laminate veneers up to 40xa0months was not significantly influenced when they were bonded onto intact teeth or onto teeth with ECR.Clinical relevanceWhen no caries is present, it may not be necessary to replace existing composite restorations prior to cementation of ceramic laminate veneers.

Bonding of Glass Ceramic and Indirect Composite to Non-aged and Aged Resin Composite

PURPOSEnSince adhesion of the restorative materials to pre-polymerized or aged resin composites presents a challenge to the clinicians, existing restorations are often removed and remade prior to cementation of fixed dental prostheses (FDPs). This study evaluated bond strength of non-aged and aged resin composite to an indirect resin composite and pressed glass ceramic using two resin cements.nnnMATERIALS AND METHODSnDisk-shaped specimens (diameter: 3.5, thickness: 3 mm) (N = 160) produced from a microhybrid resin composite (Quadrant Anterior Shine) were randomly divided into eight groups. While half of the specimens were kept dry at 37°C for 24 h, the other half was aged by means of thermocycling (6000 times, 5°C to 55°C). The non-aged and aged resin composites were bonded to a highly filled indirect composite (Estenia) and a pressed glass ceramic (IPS Empress II) using either a photopolymerizing (Variolink Veneer) or a dual-polymerizing (Panavia F2.0) resin cement. While cementation surfaces of both the direct and indirect composite materials were silica coated (30 µm SiO2, CoJet-Sand) and silanized (ESPE-Sil), ceramic surfaces were conditioned with hydrofluoric acid (20 s), neutralized, and silanized prior to cementation. All specimens were cemented under a load of 750 g. Shear force was applied to the adhesive interface in a universal testing machine (1 mm/min). Failure types of the specimens were identified after debonding.nnnRESULTSnSignificant effects of aging (p < 0.05), restorative material (p < 0.05), and cement type (p < 0.05) were observed on the bond strength (3-way ANOVA). Interaction terms were also significant (p < 0.05) (Tukeys test). After aging, in terms of bond strength, indirect composite and pressed glass ceramic in combination with both cements showed no significant difference (p > 0.05). Both indirect composite (24.3 ± 5.1 MPa) and glass ceramic in combination with Variolink (22 ± 9 MPa) showed the highest results on non-aged composites, but were not significantly different from one another (p > 0.05). On the aged composites, indirect composite and glass ceramic showed no significant difference in bond strength within each material group (p > 0.05), with both Panavia (17.2 ± 6 and 15 ± 5.5 MPa, respectively) and Variolink (19 ± 8, 12.8 ± 5.3 MPa, respectively), but in all groups, glass ceramic-Variolink on aged composite revealed the lowest results (12.8 ± 5.3 MPa). Among all groups, predominantly cohesive failures were observed in the indirect resin composite substrate (79 out of 80) as opposed to the ceramic (18 out of 80) (p < 0.05) (Chi square).nnnCONCLUSIONnRegardless of the resin cement type, considering the bond values and the failure types, the adhesion quality of indirect composite cemented to non-aged and aged resin composite was superior with both cements compared to that of pressed glass ceramic.