New adhesive rehabilitation technique with indexed occlusal tabletops made by 3D printing technology

OBJECTIVE

In oral rehabilitation, a full mouth minimal invasive treatment can represent a major challenge for the patient and the dentist. The purpose of this article is to present a new technique to restore eroded teeth and recover the vertical dimension with a simple and predictable technique.

CLINICAL CONSIDERATIONS

Occlusal tabletop restorations are a suitable conservative option to restore anatomy and vertical dimension augmentation but highly sensitive. The cementation of those restorations without stable landmarks, the cement excess removal, the insertion path, or the time needed are some of the difficulties can be faced. Now a days with the new CAD-CAM techniques is possible to develop a new occlusal tabletop manufacturing alternative utilizing 3D-printed technology by unifying the restorations with a customized connector that allows us to print several onlays at same time, as a single object, also being cemented at once.

CONCLUSIONS

This protocol reduces the technique sensitivity of a vertical dimension oral rehabilitation process, reduce the chair time, enhancing the patient-comfort and delivers a unique way to restore dental lost anatomy as a definitive or temporary way with printing materials.

CLINICAL SIGNIFICANCE

With the advent of new CAD-CAM 3D printing materials, which are increasingly versatile and gaining favor among clinicians, it is now possible to address complex clinical situations with greater predictability. This technology enables the development of treatment solutions that are both effective and efficient, consequently reducing clinical time for the patient.

Carbon dots combined with phytosphingosine inhibit acid-induced demineralization of hydroxyapatite in vitro

OBJECTIVES

To study the effects of carbon dots (CDs), in combination with phytosphingosine (PHS), against acid-induced demineralization of hydroxyapatite in vitro.

METHODS

CDs were generated from citric acid and urea by microwave heating. Transmission electron microscope (TEM), FT-IR, and fluorescence intensity were used to characterize the CDs. A hydroxyapatite (HAp) model was used to investigate the protective effects of CDs, PHS, and their combinations with and without a salivary pellicle against acid-induced demineralization in vitro. Ca2+ release as a parameter to evaluate the inhibition of demineralization was measured by capillary electrophoresis. The interactions between CDs, PHS, and HAp discs were investigated using a fluorescence detector.

RESULTS

Uniform-sized CDs were synthesized, showing typical optical characteristics. CDs exhibited no inhibition of acid-induced demineralization in vitro, in contrast to PHS. Notably, a pre-coating of CDs increased the protective effects of PHS against acid-induced demineralization, which was not disturbed by the presence of a salivary pellicle and Tween 20. Scanning electron microscope (SEM) confirmed the binding and layers formed of both CDs and PHS to the HAp surfaces. Based on fluorescence spectra CDs binding to HAp seemed to be dependent on Ca2+ and PO43- interactions.

CONCLUSIONS

CDs combined with PHS showed protective effects against acid-induced demineralization of HAp discs in vitro.

Marginal adaptation and fracture resistance of virgilite-based occlusal veneers with varying thickness

STATEMENT OF PROBLEM

CAD/CAM occlusal veneers have been developed for minimally invasive prosthetic restoration of eroded teeth. Marginal adaptation and fracture resistance are crucial for the long-term survivability and clinical success of such restorations. Virgilite-based lithium disilicate glass-ceramic is a newly introduced material with claims of high strength. However, constructing occlusal veneers from this material of varying thickness has not been investigated.

PURPOSE

The current study aimed to assess the impact of CAD/CAM occlusal veneer thickness and materials on marginal adaptation and fracture resistance.

MATERIALS AND METHODS

Thirty-two occlusal veneers were constructed and divided into two groups (n = 16) based on the CAD/CAM material into Brilliant Crios and CEREC Tessera. Each group was further subdivided into two subgroups (n = 8) according to the thickness: 0.6 and 0.9 mm. Occlusal veneers were bonded to epoxy resin dies. The marginal gap was evaluated before and after thermodynamic aging. Fracture resistance and failure mode were evaluated for the same samples after aging. Marginal adaptation was analyzed using the Mann-Whitney U test. Fracture resistance was analyzed using Weibull analysis (α = 0.05).

RESULTS

The marginal gap was significantly increased following thermodynamic aging for tested groups (P < 0.001). CEREC Tessera showed a significantly higher marginal gap than Brilliant Crios before and after aging for both thicknesses (P < 0.05). CEREC Tessera recorded lower significant fracture load values compared to Brilliant Crios (P < 0.05).

CONCLUSIONS

Both CEREC Tessera and Brilliant Crios demonstrated clinically accepted marginal gap values. All groups showed fracture resistance values higher than the average masticatory forces in the premolar region except for 0.6 mm CEREC Tessera.

CLINICAL IMPLICATIONS

Reinforced composite occlusal veneers demonstrated more favorable outcomes in terms of marginal gap and fracture resistance at both tested thicknesses compared to virgilite-based lithium disilicate glass-ceramic. Additionally, caution should be exercised during the construction of occlusal veneers from virgilite-based lithium disilicate glass-ceramic with reduced thickness.

Effect of polydopamine and fluoride ion coating on dental enamel remineralization: an in vitro study

BACKGROUND

Fluoride treatment is one of the most effective dental caries prevention methods. To continuously prevent dental caries, stably immobilizing the fluoride on the tooth enamel is highly desirable. This study aimed to evaluate the remineralization of tooth enamels by one-pot coating using polydopamine and fluoride ions.

METHODS

To prepare the enamel specimens for polydopamine- and fluoride ion-coating, they were treated with polydopamine- and fluoride-containing gels. The enamel specimens were collected from human molars in a blind manner (n = 100) and were randomized into five treatment groups (n = 20, each): 1) untreated, 2) polydopamine-coated, 3) fluoride-containing gel-treated, 4) F varnish-treated, and 5) polydopamine- and fluoride ion-coated enamels. Vickers hardness number (VHN), morphology, and fluoride contents of the specimens were measured before and after the pH-cycling regimen.

RESULTS

Polydopamine- and fluoride ion-coated enamels showed the highest fluoride content and lowest VHN reduction among the samples. The fluoride content of the polydopamine/fluoride ion (PD/F)-coated enamel was increased to 182 ± 6.6%, which was far higher than that of the uncoated enamel (112.3 ± 32.8%, P < 0.05). The changes in the VHN values (ΔVHN) of PD/F-coated enamel substrates showed a slight reduction in the VHN (-3.6%, P < 0.05), which was far lower than that in the control group (-18.9%, P < 0.05). In addition, scanning electron microscopy clearly supported the effect of polydopamine- and fluoride ion-coatings on the remineralization of enamel specimens.

CONCLUSION

Our findings suggest that one-pot treatments with polydopamine and fluoride ions could significantly enhance remineralization by inhibiting enamel demineralization through the prolonged retention of fluoride ions.

Comparison of the shear bond strength in Giomer and resin-modified glass ionomer in class V lesions

Introduction

There are several cosmetic, restorative materials to restore non-carious Cervical Lesions (NCCLs). The aim of this study was to specify and compare the shear bond strength of Giomer and resin-modified glass ionomer in Class V lesions so that whether Giomer showed a better shear bond strength, it could be used instead of RMGI to restore NCCLs because of its better esthetic.

Method

ology: 20 maxillary and 20 mandibular intact premolars were collected. Each group of 20 samples was divided into two 10-tooth subgroups of A and B. A class V preparation was made on the buccal surface of the samples with 2*2*3 mm dimensions using a diamond bur. Also, the crossing path of the universal machine chisel was prepped with 2 mm depth up to incisal edge. For group A, after applying BeautiBond and curing it, Beautifil II Giomer was placed in nylon cylinders and the cylinders were placed in the middle cervical region and cured for 20 s. For group B, 1 spoon powder of Fuji II RMGI was mixed with two drops of its liquid and transported to nylon cylinders and placed in the middle cervical region, then cured for 20 s. The nylon cylinders were removed from all 40 samples. Then, all teeth were thermocycled and then tested using a universal machine with the force of 20 MPa and the speed of 1 mm/min until they fractured to assess their shear bond strength. The obtained data was analyzed using SPSS v.26. The significance level was considered 0.05.

Results

There was no significant difference between Giomer (4.97 ± 2.36) and the resin-modified glass ionomer (3.41 ± 2.71) groups as regards their shear strength (p = 0.059). Likewise, there was no significant difference in shear bond strength between Giomer and RMGI groups as regards jaw type (P = 0.326).

Conclusion

The paper suggests that Giomer and resin-modified glass ionomer groups did not differ significantly in terms of their shear bond strength and that both can be utilized to treat Class V lesions. Furthermore, there was no significant difference between the shear bond strength in terms of jaw type.

Case Report: A digital workflow in the treatment of bruxism in a young patient

Bruxism is increasingly common in today's stressful world and affects mainly young patients. It is a combined disease that involves dentition and its supporting structures, muscles, ligaments and the temporomandibular joint (TMJ). Here we present a complete combined analog and digital clinical protocol in a patient with parafunction.

A young patient sought help due to impaired aesthetics, as a result of abraded tooth surfaces and severe symptoms of TMJ. We implemented a therapeutic protocol of six stages: deprogramming of the muscles and determination of treatment position and digital optimization; realization of the morphological plan for the upper dentition; non-invasive repositioning of the lower jaw by splint therapy; splint placement and follow-up; morphological planning of the lower dentition and replacement of the splint with fixed prosthesis with follow-up; and completion of the case with ceramic restorations.

The digitally modeled temporary constructions for the upper jaw were made of PMMA and placed in the patient's mouth together with the splint on the lower jaw, made of Ceramill Splintec. After an adaptation period, all restorations were replaced by permanent zirconia.

We achieved restoration of the defects of the dental arches and hard dental tissues and recovery to normal height of the lower third of the face (vertical dimension occlusion), fixed a stable and balanced position of the lower jaw, and repaired the normal physiological position of the TMJ for the patient. Аfter a multi-stage treatment we received a result satisfying the patient, the dentist and the dental technician. Aesthetics and function were restored, and clinical symptoms were removed from the TMJ.

Ultrathin CAD-CAM glass ceramic and composite resin occlusal veneers for the treatment of severe dental erosion: An up to 3-year randomized clinical trial

STATEMENT OF PROBLEM

Ultrathin bonded posterior occlusal veneers represent a conservative alternative to traditional onlays and complete coverage crowns for the treatment of erosive dental wear. Data regarding the clinical performance of ceramic and composite resin ultrathin occlusal veneers are lacking.

PURPOSE

The purpose of this prospective randomized clinical trial was to evaluate the influence of computer-aided design and computer-aided manufacturing (CAD-CAM) restorative material (ceramic versus composite resin) on the clinical performance of ultrathin occlusal veneers bonded to worn posterior teeth.

MATERIAL AND METHODS

Eleven participants (mean age, 30.4 years) had their posterior teeth restored with 24 ceramic (e.max CAD) and 36 composite resin (Lava Ultimate) ultrathin occlusal veneers. The material type was assigned randomly. The tooth preparations were trial restoration driven and included immediate dentin sealing (OptiBond FL). The intaglio surfaces of the ceramic restorations were etched with hydrofluoric acid and silanated, and the composite resins were airborne-particle abraded and silanated. The tooth preparations were airborne-particle abraded and etched with phosphoric acid before restoration insertion. All restorations were adhesively luted with preheated composite resin (Filtek Z100). The participants were evaluated according to the modified United States Public Health Service (USPHS) criteria at baseline and then each year for up to 3 years. Survival rates were estimated with time to failure (primary outcome of interest) as the endpoint (scores 4 or 5).

RESULTS

No restorations were lost. Five partial failures, in the form of chipping (all scored 4), were observed in the composite resin group (Lava Ultimate). The Kaplan-Meier survival rates were 100% for ceramic and 84.7% (SE 0.065%) for composite resin. Differences between the 2 groups were not statistically significant (P=.124). In the surviving restorations, significant difference (P=.003) was found for surface roughness as restorations in the composite resin group experienced some surface degradation.

CONCLUSIONS

The findings of this medium-term clinical trial suggest that ceramic (e.max CAD) and composite resin (Lava Ultimate) CAD-CAM ultrathin occlusal veneers presented statistically comparable performance regardless of the minor partial failures (restorable chipping) observed in the composite resin group. Higher surface degradation was observed in the composite resin group.

Fracture Resistance and Failure Mode of Mandibular Molar Restored by Occlusal Veneer: Effect of Material Type and Dental Bonding Surface

This study assesses the effect of the material type (lithium disilicate, zirconia, and polymer-infiltrated ceramic) and dental bonding substrates (dentin, dentin with intra-coronal cavity, and dentin with composite filling) on the fracture resistance and failure mode of molars restored by occlusal veneers. Methods: Ninety occlusal veneers, fabricated from either lithium disilicate, zirconia, or polymer-infiltrated ceramic, were adhesively bonded to teeth prepared with either dentin, dentin with intra-coronal cavity, or dentin with composite filling. All specimens were thermally aged (5000 cycles), then load cycled (120,000 cycles). Each specimen was subjected to a compressive load through fracture, then was examined (×20) to identify the fracture type. Data were statistically analyzed. Results: Material type and dental substrate had no significant effect on the fracture resistance of adhesively retained occlusal veneer restorations. For each material, no significant differences were found between veneers bonded to dentin, dentin with intra-coronal cavity, and dentin with composite filling. Additionally, within each bonding substrate, there were no significant differences between lithium disilicate, zirconia, and polymer-infiltrated ceramic veneers. The adhesive failure was recorded mainly with zirconia occlusal veneer restorations. Conclusions: Considering the fracture results, lithium disilicate, zirconia, and polymer-infiltrated ceramic occlusal veneers perform well whatever the type of dental bonding surface. When the dental bonding surface varies, different occlusal veneer materials should be considered. Occlusal veneers bonded to dentin, dentin with composite filling, or dentin with an intra-coronal cavity exhibited a fracture resistance exceeding the average human masticatory forces in the molar area.

In Vitro Effect of Acidic Solutions and Sodium Fluoride on Surface Roughness of Two Types of CAD-CAM Dental Ceramics

Objectives

This study assessed the effect of immersion in acidic solutions and sodium fluoride on surface roughness of dental ceramics.

Materials and Methods

40 blocks of Vitablocs Mark II and IPS e.max CAD (5 × 5 × 3) were prepared. The samples were divided into five groups (n = 8) for immersion in artificial saliva (control), artificially prepared gastric acid, acetic acid, 0.02% sodium fluoride + gastric acid, and 0.02% sodium fluoride + acetic acid. The samples were immersed for 168 hours in the respective solutions except for sodium fluoride, in which the samples were immersed for 69 hours. The surface roughness of samples was measured before and after immersion using a profilometer. The surface roughness changes of three specimens of each group were evaluated by scanning electron microscopy (SEM). Data were analyzed using one-way and two-way ANOVA, Tukey's test, and independent t-test.

Results

Significant changes were noted in Ra (P=0.002) and Rq (P < 0.0001) in both types of ceramics. The lowest changes in Ra and Rq parameters were seen in artificial saliva and gastric acid and highest changes occurred following immersion in 0.02% sodium fluoride + acetic acid and 0.02% sodium fluoride + gastric acid, respectively. Changes in Rz were also significant following immersion in Vitablocs Mark II (P < 0.05). Immersion in 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid produced a rougher surface on both types of ceramics (SEM).

Conclusion

Exposure of Vitablocs Mark II CAD and IPS e.max CAD to 0.02% sodium fluoride + gastric acid and 0.02% sodium fluoride + acetic acid significantly increased their surface roughness, while for Vitablocs Mark II, lager defects were seen on its surface.

Five-year clinical evaluation of a universal adhesive: A randomized double-blind trial

OBJECTIVE

To evaluate the five-year clinical performance of Scotchbond Universal Adhesive (SU; 3M Oral Care, St. Paul, MN, USA) in non-carious cervical lesions (NCCLs) using two evaluation criteria.

METHODS

Thirty-nine patients participated in this study. Two hundred restorations were assigned to four groups: SU-ERm: etch-and-rinse + moist dentin; SU-ERd: etch-and-rinse + dry dentin; SU-Set: selective enamel etching; and SU-SE: self-etch. A nanofilled composite resin was placed incrementally. The restorations were evaluated at baseline and after 5 years using both the World Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. The survival rates (retention/fractures) were calculated with the Kaplan-Meier and the log-rank test. For the secondary outcomes, Friedman repeated measures analysis of variance by rank was applied (α = 0.05).

RESULTS

After 5 years the recall rate was 86%. The retention/fracture rates were 93% for Erm and ERd, 88.4% for SEet and 81.4% for SE. A significant difference was observed for SE vs. ERd and SE vs. ERm (p = 0.01). Also, marginal discoloration and adaptation showed significant differences with ERm and ERd resulting in fewer marginal discrepancies than SE (p < 0.05).

SIGNIFICANCE

After 5 years, the clinical behavior of the universal adhesive in the etch-and-rinse strategy was better when compared to the self-etch strategy. The use of selective enamel etching is highly recommended for the self-etch strategy. The FDI and USPHS evaluation criteria showed similar results after 5 years.

Effect of preparation design on the fracture behavior of ceramic occlusal veneers in maxillary premolars

OBJECTIVES

The fracture strengths of four types of occlusal veneers and a traditional full crown ceramic restoration and the influence of preparation design on the stress of restorations were examined.

METHODS

Forty intact maxillary premolars randomly divided into five groups were prepared based on the demands of type O (occlusal surface coverage), OF (occlusal and lingual surface coverage), POF (occlusal, lingual, and mesial surface coverage), and POFP (occlusal, lingual, mesial, and distal surface coverage) veneers and full crown, and then restored by glass ceramic. Specimens were subjected to fracture resistance tests after cyclic loading. The fracture strengths and modes were analyzed statistically. The level of significance was set at α = 0.05. One maxillary premolar was prepared for type O, OF, POF, POFP veneer and full crown, and then scanned to establish finite element models. The mean fracture load was applied vertically to calculate the maximum principal stress on the ceramic.

RESULTS

Type O veneer showed higher fracture strength than type POF and POFP veneers (P < 0.05). Both type O and OF veneers exhibited higher fracture strength than full crown (P < 0.05). No significant difference in failure mode was observed. The maximum principal stress for type O, OF, POF, POFP veneers, and full crown increased progressively and concentrated at the bonding surface directly beneath the loading area.

CONCLUSIONS

Four types of occlusal veneer showed fracture strengths that considerably exceeded normal biting forces. They represent conservative alternatives to full crowns and present a viable treatment for severely worn teeth.

CLINICAL SIGNIFICANCE

The occlusal veneers with different preparation designs, including type O, OF, POF and POFP veneers, show higher fracture resistances than traditional full coverage crowns that considerably exceed the normal biting forces. Therefore, these represent conservative alternatives to crown restorations and present a viable treatment for restoring severely worn teeth.

Effect of pediatric multivitamin syrups and effervescent tablets on the surface microhardness and roughness of restorative materials: An in vitro study

Background/purpose

Multivitamin syrups and effervescent tablets are commonly used for dietary support in children; however, these preparations may have detrimental effects on the surface of restorative materials. The aim of this study was to evaluate the effect of two multivitamin syrups and two effervescent tablets taken daily on the surface microhardness and roughness of two different restorative materials.

Materials and methods

The study groups were comprised of a conventional glass ionomer cement, Ketac Molar, and a giomer, Beautifil II. A total of 140 disc-shaped specimens were prepared and randomly assigned to 5 subgroups. The samples were immersed in 4 multivitamins (Supradyne syrup, Supradyne effervescent, Sambucol syrup, Sambucol effervescent) and deionized water (control group) for 2 min once a day for 28 days. Surface microhardness and roughness measurements were recorded at baseline and on the 7th, 14th, 21st and 28th days. Surface microhardness was measured using a Vickers hardness tester and surface roughness was determined using a profilometer.

Results

For all subgroups; the surface microhardness values of the Ketac Molar and Beautifil II demonstrated a statistically significant decrease from the baseline to the 28th day measurements (p < 0.05), while the surface roughness displayed increased values that were found to be statistically significant (p < 0.05). The Ketac Molar surface roughness values were significantly higher than Beautifil II in all subgroups for all measurement days (p = 0.0001).

Conclusion

The prolonged use of multivitamin syrups and effervescent tablets may have negative effects on the physical properties of restorative materials.

Prevention of Enamel Softening by Rinsing with a Calcium Solution before Dental Erosion

OBJECTIVES

This in situ study aimed to evaluate whether rinsing with a calcium-containing solution prior to an erosive attack reduces the softening of enamel.

MATERIALS AND METHODS

A total of 240 bovine enamel samples with determined baseline surface microhardness (KHN) were allocated to 5 runs in which each of the 12 volunteers performed the following experiment: 4 enamel samples were inserted in a custom-made intraoral appliance and carried in the mouth (upper jaw) for 30 min before each volunteer either rinsed his mouth for 60 s with a fluoride- and stannous ion-containing dental erosion protection mouth rinse as positive control (run 1), milk (run 2), a solution prepared from a 500-mg calcium effervescent tablet dissolved in 100 mL (run 3) or 200 mL (run 4) water, or did not perform any rinsing with a test solution before the erosive attack (run 5, negative control). To simulate the erosive attack, volunteers rinsed their mouth with a commercial soft drink (Sprite Zero) for 60 s and afterwards with water to stop the erosive process. Finally, surface microhardness was measured again and hardness loss (ΔKHN) calculated. A mixed effect model was fitted to the data set to investigate whether the different runs showed differences with respect to ΔKHN.

RESULTS

No significant difference in softening of enamel (mean of ΔKHN; lower confidence level/upper confidence level) was observed between the negative control run 5 (50.7; 60.8/40.6), run 2 (50.7; 60.8/40.6), run 3 (38.7; 48.8/28.6) and run 4 (40.7; 50.8/30.6) (p > 0.05, respectively). Enamel softening in the positive control run 1 (25.4; 35.6/15.3) was significantly lower compared to the softening in run 5 (p < 0.001). No significant difference was observed between run 1 and run 3 (p = 0.09).

CONCLUSION

Other than the fluoride- and stannous ion-containing dental erosion protection mouth rinse, none of the investigated calcium-containing solutions is able to significantly reduce erosion-induced softening of enamel.

Effect of air-abrasion pre-treatment with bioactive glass 45S5 on enamel surface loss after erosion/abrasion challenge

OBJECTIVES

The aim of this in vitro study was to evaluate the effect of air-abrasion surface pre-treatment with bioactive glass (BAG) 45S5 on enamel surface loss after erosion/abrasion challenge.

METHODS

Twenty-four sound bovine incisors were used for this study. Four experimental groups (n=12) were assigned as follows: Group 1 was the negative control group, Group 2 specimens were treated with a SnF₂ gel (positive control group), Group 3 specimens were air-abraded with BAG 45S5 (ProSylc) and Group 4 received both treatments. The specimens were submitted to erosion/abrasion challenge using a common soft drink. Enamel surface loss was evaluated using an optical profilometer. Additionally, surface roughness (VSI method) and surface microhardness (Vickers method) changes were evaluated, as well as SEM and EDS analyses were performed on enamel surface. The data were statistically analyzed using one-way ANOVA and Tukey's post-hoc test at a level of significance a=0.05.

RESULTS

Surface pre-treatment with BAG 45S5 reduced surface loss in comparison with negative control group (p<0.001), which exhibited the highest surface loss of the experimental groups (p<0.05). The positive control group (SnF₂ treatment) and Group 4 specimens, which received both air-abrasion pre-treatment and SnF₂ treatment, presented the lowest surface loss (p<0.05), but did not show significant differences to each other (p=0.65).

SIGNIFICANCE

Air-abrasion pre-treatment with BAG 45S5 may be beneficial as an in-office preventive method for the limitation of enamel erosive wear induced by excessive consumption of soft drinks. The clinical significance of the results regarding this preventive method should be confirmed by clinical studies.

Evaluation of a clinical preventive treatment using Er,Cr:YSGG (2780 nm) laser on the susceptibility of enamel to erosive challenge

The purpose of this in vitro study was to evaluate the effect of a clinical preventive treatment using Er,Cr:YSGG laser irradiation on bovine enamel susceptibility after erosive challenge. Twelve sound bovine incisors were used and twenty-four enamel specimens were prepared in total. Two experimental groups (n = 12) were assigned as follows: Group 1 was the control group and in Group 2, the enamel specimens were irradiated with an Er,Cr:YSGG (2780 nm) laser system for 20 s, with average output power of 0.25 W, pulse repetition rate at 20 Hz without water or air flow and the pulse duration was fixed at 140 μsec. The tip diameter was 600 μm, the tip to tissue distance was 1 mm, the speed of handpiece movement was 2 mm/s, the power density was 88.34 W/cm², and the fluence was 31.25 J/cm². The specimens were submitted to erosive challenge using a common soft drink. Surface microhardness changes, surface roughness changes, and surface loss were evaluated after erosive challenge. The data were statistically analyzed using one-way ANOVA and Tukey's post-hoc test at a level of significance a = 0.05. Er,Cr:YSGG laser-treated enamel exhibited significantly less decrease in surface microhardness and significant less surface loss compared to control enamel after the erosive challenge (p < 0.05). The experimental groups did not show significant differences in surface roughness increase after the erosive challenge (p > 0.05). Er,Cr:YSGG laser treatment may be promising for the limitation of enamel erosive tooth wear induced by excessive consumption of soft drinks. Clinical studies are needed to clarify whether this protective effect is clinically significant.

Ultrathin CAD-CAM Ceramic Occlusal Veneers and Anterior Bilaminar Veneers for the Treatment of Moderate Dental Biocorrosion: A 1.5-Year Follow-Up

Dental biocorrosion can produce a devastating impact on oral health. The restorative phase of the treatment should not cause additional damage of the remaining sound tooth structure. Ultrathin occlusal veneers are a conservative alternative to traditional onlays and complete crowns for the treatment of severe biocorrosive lesions. This strategy is explained in the present case report through a full-mouth rehabilitation of a patient with moderate biocorrosion. Maxillary anterior teeth were restored using the bilaminar technique (lingual direct composite veneers with labial ceramic veneers) and posterior teeth using ultrathin CAD-CAM ceramic occlusal veneers. The technical aspects required for the implementation of this new restorative design are presented with a special emphasis on the control of tooth preparation based on diagnostic wax-up, provisionalization, and the use of CAD-CAM technology.

Effect of Different Computer-aided Design/Computer-aided Manufacturing (CAD/CAM) Materials and Thicknesses on the Fracture Resistance of Occlusal Veneers

The aim was to evaluate, in vitro, the influence of different computer-aided design/computer-aided manufacturing (CAD/CAM) materials (IPS e.max CAD, Vita Enamic, and Lava Ultimate) and thicknesses (0.6 mm and 1.5 mm) on the fracture resistance of occlusal veneers. Sixty human third molars were prepared to simulate advanced erosion of the occlusal surface, and the teeth were randomly divided into six experimental groups (n=10) according to the material and thickness used to build the veneers. Ten sound teeth formed the control group. The veneers were adhesively luted and submitted to mechanical cyclic loading (1 million cycles at 200-N load). The fracture resistance test was performed in a universal testing machine. The failures were classified as "reparable" and "irreparable." According to two-way analysis of variance and the Tukey test, the interaction (material × thickness) was significant ( p=0.013). The highest fracture resistance was obtained for IPS e.max CAD at a 1.5-mm thickness (4995 N) and was significantly higher compared to the other experimental groups ( p<0.05). The lowest fracture resistance was obtained for Vita Enamic at 0.6 mm (2973 N), although this resistance was not significantly different from those for IPS e.max CAD at 0.6 mm (3067 N), Lava Ultimate at 0.6 mm (3384 N), Vita Enamic at 1.5 mm (3540 N), and Lava Ultimate at 1.5 mm (3584 N) ( p>0.05). The experimental groups did not differ significantly from the sound teeth (3991 N) ( p>0.05). The failures were predominantly repairable. The occlusal veneers of IPS e.max CAD, Vita Enamic, and Lava Ultimate, with thicknesses of 0.6 mm and 1.5 mm, obtained fracture resistances similar to those associated with sound teeth.

Effect of Fluoride Varnish Containing CPP-ACP on Preventing Enamel Erosion

This study aimed to investigate the effect of a fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate treatment on the prevention of enamel erosion, and it compared the results with those of other fluoride varnishes. Fifty enamel specimens obtained from bovine incisors were randomly divided into five groups (n = 10) based on the type of surface pretreatment used: intact enamel (Group 1); intact enamel+erosive cycles (Group 2); intact enamel+MI varnish+erosive cycles (Group 3); intact enamel+Clinpro White varnish+erosive cycles (Group 4); and intact enamel+Duraphat varnish+erosive cycles (Group 5). The specimens were subjected to erosive cycles for five days. The surface roughness was evaluated using atomic force microscopy. The results were statistically analyzed using one-way ANOVA and Tukey's tests. Group 1 had the smoothest surfaces. After the erosive cycles, the greatest surface roughness values were observed in Group 2, followed by Groups 5, 4, and 3, respectively. Statistically significant differences were observed among all groups (p < 0.05). The application of fluoride varnishes had some positive effects on preventing enamel erosion; however, the most effective agent was fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate.

Amazonian delicacy tucupi is as erosive as a cola-based soft drink

OBJECTIVE

Acidic diets are advocated as main risk factor for tooth erosion, which could be prevented, or at least controlled, if patients were early advised. It is important to identify, hence, if possible dietary constituents regionally consumed on large scale, such as tucupi, a low-pH yellowish-green color and strong flavor delicacy made from the juice of a bitter cassava, may explain its occurrence in specific patient groups. This cross-over in situ/ex vivo study evaluated tucupi's ability to promote erosion of bovine enamel by assessing its percentage of surface microhardness change (%SMHC), taking a cola-based soft drink and human saliva as positive and negative controls.

DESIGN

For three 7-days spaced out legs of 7 days each, nine volunteers wore palatal devices with three bovine enamel blocks, which were challenged with one of the following solutions: TUC-tucupi (n=27); COL-cola-based soft drink (n=27); SAL-saliva (n=27). Erosive challenges were performed extra-orally (4×/day) by dropping TUC or COL at room temperature on specimens. After 5min, palatal devices were replaced into the mouth. SAL permanently acted as the negative control while volunteers solely wore the device. One-way ANOVA followed by Tukey's post-hoc tests (α=0.05) were applied.

RESULTS

TUC promoted an enamel %SMHC (-21.56±10.08(a)) similar than that promoted by COL (-18.19±12.99(a); p=0.275), which were both significantly higher than that promoted by SAL (-1.86±13.65(b); p<0.0001).

CONCLUSIONS

Besides the most worldwide appreciated cola-based soft drink, the greatly consumed Amazonian delicacy tucupi can be considered a potential risk factor for tooth erosion.

Monitoring Demineralization and Subsequent Remineralization of Human Teeth at the Dentin-Enamel Junction with Atomic Force Microscopy

Using atomic force microscopy, we monitored the nanoscale surface morphology of human teeth at the dentin-enamel junction after performing successive demineralization steps with an acidic soft drink. Subsequently, we studied the remineralization process with a paste containing calcium and phosphate ions. Repeated atomic force microscopy imaging of the same sample areas on the sample allowed us to draw detailed conclusions regarding the specific mechanism of the demineralization process and the subsequent remineralization process. The about 1-μm-deep grooves that are caused by the demineralization process were preferentially filled with deposited nanoparticles, leading to smoother enamel and dentine surfaces after 90 min exposure to the remineralizing agent. The deposited material is found to homogeneously cover the enamel and dentine surfaces in the same manner. The temporal evolution of the surface roughness indicates that the remineralization caused by the repair paste proceeds in two distinct successive phases.

Shear bond strength of two adhesive materials to eroded enamel

AIM

To evaluate the bond strength of one etch-and-rinse adhesive system and one resin-modified glass ionomer cement to sound and eroded enamel.

MATERIALS AND METHODS

Forty-eight bovine incisors were embedded in acrylic resin and ground to obtain flat buccal enamel surfaces. Half of the specimens were submitted to erosion challenge with pH-cycling model (3x/cola drink for 7 days) to induce eroded enamel. After that, all specimens were randomly assigned according to adhesive material: etch-andrinse adhesive system (Adper Single Bond 2 - 3M ESPE, USA) or resin-modified glass ionomer cement (Vitro Fil LC - DFL, Brazil). The shear bond testing was performed after 24 hours water storage (0.5 mm/min). Shear bond strength means were analyzed by two-way ANOVA and Tukey post hoc tests (p < 0.05).

RESULTS

Adper Single Bond 2 showed the highest bond strength value to eroded enamel (p < 0.05), whereas no difference was observed in sound enamel compared with Vitro Fil LC (p > 0.05).

CONCLUSION

Bond strength of etch-and-rinse adhesive system increases in eroded enamel, while no difference is verified to resin-modified glass ionomer cement.

CLINICAL SIGNIFICANCE

Adhesive materials may be used in eroded enamel without jeopardizing the bonding quality; however it is preferable to use etch-and-rinse adhesive system.

Saliva and dental erosion

Dental erosion is a multifactorial condition. The consideration of chemical, biological and behavioral factors is fundamental for its prevention and therapy. Among the biological factors, saliva is one of the most important parameters in the protection against erosive wear.

OBJECTIVE

This review discusses the role of salivary factors on the development of dental erosion.

MATERIAL AND METHODS

A search was undertaken on MeDLINe website for papers from 1969 to 2010. The keywords used in the research were "saliva", "acquired pellicle", "salivary flow", "salivary buffering capacity" and "dental erosion". Inclusion of studies, data extraction and quality assessment were undertaken independently and in duplicate by two members of the review team. Disagreements were solved by discussion and consensus or by a third party.

RESULTS

Several characteristics and properties of saliva play an important role in dental erosion. Salivary clearance gradually eliminates the acids through swallowing and saliva presents buffering capacity causing neutralization and buffering of dietary acids. Salivary flow allows dilution of the acids. In addition, saliva is supersaturated with respect to tooth mineral, providing calcium, phosphate and fluoride necessary for remineralization after an erosive challenge. Furthermore, many proteins present in saliva and acquired pellicle play an important role in dental erosion.

CONCLUSIONS

Saliva is the most important biological factor affecting the progression of dental erosion. Knowledge of its components and properties involved in this protective role can drive the development of preventive measures targeting to enhance its known beneficial effects.

Noncarious Cervical Lesions Restored with Three Different Tooth-Colored Materials: Two-Year Results

Introduction:

The aim of this two-year prospective clinical study was to evaluate and compare the clinical performance of three different adhesive esthetic materials in noncarious cervical lesions.

Material and Methods:

A total of 90 restorations (30 per material) were placed in 30 patients who ranged in age between 18 and 50 years and of both genders, by a single operator with no previous preparation. The restoration of noncarious cervical lesions was done with either a microfilled composite (Esthet.X/Dentsply/De Trey, Konstanz, Germany, and Prime&Bond NT/Dentsply/De Trey), a nanohybrid composite (TetricEvoCeram/Vivadent, Schaan, Liechtenstein, and AdheSE/Vivadent), or a compomer (Dyract eXtra/Dentsply/De Trey and Xeno III Dentsply/De Trey). All restorations were evaluated by independent examiners using a modified US Public Health Service criteria at baseline and after 12 and 24 months for six clinical categories. Data were analyzed statistically by Pearson's chi-square or the Fisher's exact test at 5% significance level (p&lt;0.05).

Results:

Results showed that most of the restorations were clinically satisfactory after 12 and 24 months, with no statistically significant differences among the three groups for all evaluated criteria.

Conclusion:

Treatment of noncarious cervical lesions using composite and compomer materials, combined with the appropriate adhesive systems and properly implemented restorative procedures, gives satisfactory results after a two-year evaluation period.

Erosive potential of different types of grape juices

The purpose of the present study was to evaluate the erosive potential of different types (concentrated and powdered) and commercial brands of industrialised grape juices. The pH of all five fruit drinks was measured at two time points: immediately after preparation and 24 hours later. Sixty specimens of bovine enamel were randomly allocated and immersed in different types of grape juice (n = 10) for 10 minutes four times a day for fifteen days. The enamel alteration was analysed using surface Knoop microhardness (KHN) and surface roughness (Ra) tests at baseline and on the 5(th), 10(th) and 15(th) days of the experiment. Two way ANOVA, Tukey's post hoc and Pearson's correlation tests were used for statistical analysis (α = 5%). The grape juices presented pH values ranging from 2.9 to 3.5. All of the tested juices promoted significant enamel mineral loss (p < 0.05) on the first evaluation (5(th) day of immersion) and produced a significant increase in the mean roughness from the 10(th) day on when compared to the control group (p < 0.05). By the 15(th) day, all of the beverages had produced surface roughnesses that were significantly higher than that of the control group. The results suggest that all grape juices, regardless of their commercial presentation, present erosive potential.

Restoration of noncarious cervical lesions: when, why, and how

At this time, restoration of noncarious cervical lesions (NCCLs) is a common occurrence in clinics nowadays. Some reasons for this are the growth of the elderly population, a smaller rate of tooth loss, and possibly the increase of some etiologic factors. These factors include inadequate brushing techniques in gingival recession cases, corrosive food and drink consumption, and occlusal stress concentrating factors (occlusal interferences, premature contacts, habits of bruxism, and clenching). Unfortunately, Class V restorations also represent one of the less durable types of restorations and have a high index of loss of retention, marginal excess, and secondary caries. Some causes for these problems include difficulties in isolation, insertion, contouring, and finishing and polishing procedures. This work aims to help dentists in choosing the best treatment strategy, which necessarily involves steps of problem identification, diagnosis, etiological factor removal or treatment, and, if necessary, restoration. Finally, appropriate restorative techniques are suggested for each situation.

Erosion and abrasion on dental structures undergoing at-home bleaching

This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled.

Prevention of erosive/abrasive enamel wear due to orange juice modified with dietary supplements

OBJECTIVE

The aim of this study was to evaluate the erosive/abrasive enamel wear after contact with orange juices modified with different dietary supplements.

METHODS

A total of 96 bovine enamel samples were prepared and allocated to eight groups (1-8; n = 12). Samples were eroded (120 s) in 200 ml of the following eight solutions: 1: water (control), 2: orange juice, 3: water + calcium effervescent tablet, 4: orange juice + calcium effervescent tablet, 5: water + 0.75 g acid/base regulating powder (Probase), 6: water + 0.375 g Probase, 7: orange juice + 0.75 g Probase and 8: orange juice + 0.375 g Probase. After erosion, the samples were brushed with 40 brushing strokes (load 2.5 N). Enamel wear was measured using surface profilometry after 20 and 40 cycles of erosion/abrasion respectively.

RESULTS

Highest mean enamel wear (± SD) after 20 and 40 cycles of erosion/abrasion was observed for the unmodified orange juice (group 2) (0.605 ± 0.240 μm; 1.375 ± 0.496 μm respectively). The enamel wear in all other groups (3-8) was significantly lower (P < 0.0001 respectively) with no significant difference within these groups and compared with water (control).

CONCLUSION

Erosive/abrasive enamel wear induces by orange juice and tooth brushing could be reduced significantly by modification with free available dietary supplements.

The erosive effects of saliva following chewing gum on enamel and dentine: an ex vivo study

OBJECTIVES

The primary objective was to determine the erosive effect of expectorated saliva, following chewing acidic gum, on enamel and dentine samples, using a non-acidic gum as a negative control. Secondary objectives were to determine the effect of brushing enamel and dentine samples and the effect of individual saliva pH and buffering.

DESIGN

A single-centre, single-blind, placebo-controlled, two-way crossover study.

SETTING

A clinical trial, involving healthy participants, undertaken at Bristol Dental School and Hospital.

METHODS

Eight healthy participants expectorated saliva onto prepared enamel and dentine samples while chewing gum (strawberry flavoured acidic gum [active] or peppermint flavoured non-acidic gum [control]). Half of the enamel and dentine samples were brushed before measurement by contact profilometry.

MAIN OUTCOME MEASURES

Mean enamel and dentine erosion, with and without brushing and the relationship to salivary buffering.Results At 10 days, mean depth of surface loss from dentine samples (95% CI), following chewing of acid-containing gum and subsequent brushing, was -11.34 μm (2.22 μm) and from un-brushed dentine samples was -11.02 μm (1.71 μm). No significant erosion was noted for other groups.

CONCLUSIONS

Frequent chewers of acid-containing gums are susceptible to dentine erosion even in the presence of good salivary buffering. Enamel erosion was insignificant within the time constraints of the present study but warrants further investigation.