Color and translucency stability of novel restorative CAD/CAM materials.

BACKGROUND: The wide range of restorative materials available for use in the computer-aided design/ computer-aided manufacturing (CAD/CAM) technology requires a better understanding of their esthetic properties. OBJECTIVES: The aim of the study was to assess the stability of the color and translucency of different CAD/ CAM restorative materials before and after being subjected to different staining solutions. MATERIAL AND METHODS: A total of 160 disc-shaped specimens were prepared from glass ceramic (IPS-e.max®-CAD and Celtra Duo®), high-translucency zirconia (LavaTM Plus), resin nanoceramic (LavaTM Ultimate), and hybrid ceramic (VITA ENAMIC®) CAD/CAM blocks (5 groups, n = 32). The specimen color and translucency parameter (TP) were assessed using a spectrophotometer at baseline and after subjecting the specimens to different staining solutions (coffee, cola, ginger, and water). Changes in color (ΔE) and TP (ΔTP) were calculated. The data was analyzed using the analysis of variance (ANOVA) and Tukey's post hoc test (p < 0.05). The correlation between ΔE and ΔTP was investigated using Pearson's correlation coefficient. RESULTS: Staining significantly affected the baseline color of all specimens. Ginger had the most significant effect on Lava Plus (ΔE = 4.01 ±1.2), cola on Celtra Duo (ΔE = 2.29 ±0.25) and coffee on Lava Ultimate (ΔE = 2.59 ±0.17). Generally, IPS-e.max-CAD showed the smallest ΔE. No significant differences in ΔTP were found between different staining solutions. Increased ΔE correlated with decreased translucency for all the tested materials and staining solutions. CONCLUSIONS: Staining had a marked effect on the color and translucency of the tested CAD/CAM materials. The color change was staining solutionand material-dependent, with IPS-e.max-CAD showing the greatest color stability.

Shear bond strength of a new high fluoride release glass ionomer adhesive.

OBJECTIVE: To determine the shear bond strength of a new resin glass ionomer adhesive with higher fluoride release properties when bonding orthodontic brackets. MATERIALS AND METHODS: Sixty freshly extracted human molars were collected and stored in a solution of 0.1% (weight/volume) thymol. The teeth were cleaned and polished. The teeth were randomly separated into three groups according to the enamel conditioner/etchant and adhesive used. Group I: 20 teeth conditioned with 10% polyacrylic acid and brackets bonded with the new glass ionomer adhesive. Group II: 20 teeth conditioned with 37% phosphoric acid and brackets bonded with the new glass ionomer adhesive. Group III (control): 20 teeth etched with 37% phosphoric acid and brackets bonded with a composite adhesive. RESULTS: The results of the analysis of variance comparing the three experimental groups (F = 10.294) indicated the presence of significant differences between the three groups (P = .0001). The shear bond strengths were significantly lower in the two groups bonded with the new glass ionomer adhesive whether conditioned with polyacrylic acid ( x = 3.2 +/- 1.8 MPa) or phosphoric acid (x = 2.3 +/- 1.1 MPa), while the mean shear bond strength of the composite adhesive was 5.2 +/- 2.9 MPa. CONCLUSIONS: Although the increased fluoride release from the new glass ionomer has the potential of decreasing decalcification around orthodontic brackets, the shear bond strength of the material is relatively low.

Evaluation of a new nano-filled restorative material for bonding orthodontic brackets.

AIM: To compare the shear bond strength of a nano-hybrid restorative material, Grandio (Voco, Cuxhaven, Germany), to that of a traditional adhesive material (Transbond XT; 3M Unitek, Monrovia, CA, USA) when bonding orthodontic brackets. MATERIAL AND METHODS: Forty teeth were randomly divided into 2 groups: 20 teeth were bonded with the Transbond adhesive system and the other 20 teeth with the Grandio restorative system, following manufacturer's instructions. Student t test was used to compare the shear bond strength of the 2 systems. Significance was predetermined at P 5 .05. RESULTS: The t test comparisons (t = 0.55) of the shear bond strength between the 2 adhesives indicated the absence of a significant (P = .585) difference. The mean shear bond strength for Grandio was 4.1 +/- 2.6 MPa and that for Transbond XT was 4.6 +/- 3.2 MPa. During debonding, 3 of 20 brackets (15%) bonded with Grandio failed without registering any force on the Zwick recording. None of the brackets bonded with Transbond XT had a similar failure mode. CONCLUSIONS: The newly introduced nano-filled composite materials can potentially be used to bond orthodontic brackets to teeth if its consistency can be more flowable to readily adhere to the bracket base.

Fluoride release rate from an orthodontic sealant and its clinical implications.

The objectives were to measure the rate and amount of fluoride ions released from the sealant over a period of 17 weeks and to determine whether the fluoride-releasing sealant has a recharging ability when fluoride ions are reintroduced into the environment. Disc-shaped specimens were prepared from two types of sealants: (1) 10 discs were made using a fluoride-releasing sealant and (2) 10 discs were made of a nonfluoride adhesive primer (control). An ion analyzer was used to measure the fluoride release using a fluoride ion-specific combination electrode. The results of the repeated measure analysis (F = 7.76) indicated that the fluoride-containing sealant released fluoride ions into the solution in sustained but significantly (P = .014) decreasing rates from a high of 0.074 +/- 0.04 ppm/week/mm2 in the first week to a low of 0.015 +/- 0.017 ppm/week/mm2 at the end of the 17th week. Furthermore, the Pro Seal discs had the ability to be recharged with fluoride ions introduced from a foaming solution of acidulated phosphate fluoride. The mean fluoride release rate one week after recharging was 0.354 +/- 0.095 ppm/week/mm2 and decreased to 0.014 +/- 0.009 ppm/week/mm2 after eight weeks. The control sealant showed no significant fluoride release and was unable to absorb the fluoride ions available in the solution. The fluoride-containing sealant Pro Seal released fluoride ions in sustained but significantly decreasing amounts. The Pro Seal discs had the ability to be recharged with fluoride ions.

The effect of porcelain surface conditioning on bonding orthodontic brackets.

The purpose of this study was to evaluate the effects of a new self-etching primer/ adhesive used to enhance the shear strength of orthodontic brackets bonded to porcelain surfaces. Forty-five porcelain maxillary central incisor teeth were used in the study. The teeth were divided randomly into three groups: group I (control), the porcelain teeth were etched with 37% phosphoric acid followed by a sealant and the brackets were bonded with a composite adhesive; group II, the porcelain teeth were microetched and hydrofluoric acid and silane applied and metal brackets were then bonded with the composite adhesive; and group III, the porcelain teeth were etched with phosphoric acid and a self-etching primer/adhesive applied before bonding. Brackets precoated with the adhesive were used on all three groups of teeth. All teeth were stored for 24 hours at 37 degrees C before debonding. The results of the analysis of variance (F = 10.7) indicated that there was a significant difference (P = .001) between the three groups. The mean shear bond strengths of conventional bonding using a 37% phosphoric acid and sealant was 4.4 +/- 2.7 MPa, whereas that of microetching followed by the application of hydrofluoric acid and silane was 11.2 +/- 4.7 MPa, and for the new self-etching primer/adhesive it was 10.3 +/- 5.3 MPa. The last two groups had the highest bond strength values and were not significantly different from each other.

Effect of changing a test parameter on the shear bond strength of orthodontic brackets.

The purpose of this study was to determine the effect of changing the crosshead speed of the testing machine on the shear bond strength of orthodontic brackets to enamel while standardizing all the other variables. Forty freshly extracted human molars were bonded using the Transbond XT adhesive system (3M Unitek, Monrovia, Calif). The teeth were randomly divided into two groups. In group I, the shear bond strength was measured at a crosshead speed of 5.0 mm/min, and in group II the shear bond strength was measured at a crosshead speed of 0.5 mm/ min. Within half an hour from the initial bonding of each tooth, an occlusogingival load was applied to the bracket, producing a shear force at the bracket-tooth interface. This was accomplished by using the flattened end of a steel rod attached to the crosshead of a Universal Test Machine (Zwick GmbH & Co, Ulm, Germany). The t-test results (t = 2.71) indicated that there was a significant difference (P = .014) in the shear bond strengths between the group tested at a crosshead speed of 5.0 mm/min and the group tested at a crosshead speed of 0.5 mm/min. The mean shear bond strengths for the two groups were 7.0 +/- 4.6 MPa and 12.2 +/- 4.0 MPa, respectively. These findings indicated that it is important to identify the parameters included in shear bond testing in order to enable meaningful comparisons of the performance of different materials.

Effects of using a new protective sealant on the bond strength of orthodontic brackets.

This study determines the effect of applying a new protective sealant to the enamel surface on the shear bond strengths of orthodontic brackets. Sixty teeth were randomly divided into three groups. In group 1 (control), the brackets were bonded to the etched teeth using the regular sealant. In group 2, the sealant was replaced with Pro Seal and light cured as recommended by the manufacturer; the brackets were then placed, and the adhesive was light cured. In group 3, Pro Seal was applied, the bracket with the adhesive was placed on the tooth, and both Pro Seal and the adhesive were cured simultaneously. The purpose of this modification was to reduce one of the steps during the bonding procedure. A shear force was applied at the bracket-tooth interface using a Zwick Universal Test Machine. The results of the analysis of variance (F-ratio = 1.35) indicated that the shear bond strengths of the three groups were not significantly different (P = .267) from each other. The mean shear bond strength of the control group was 4.9+/-2.1 MPa. The mean shear bond strength for teeth coated with Pro Seal and light cured followed by application and light curing of the adhesive was 4.8+/-2.3 MPa, and the mean for the teeth coated with Pro Seal and then bracket placed followed by simultaneous light curing of the sealant and the adhesive was 4.0+/-1.5 MPa.

Effect of antimicrobial monomer-containing adhesive on shear bond strength of orthodontic brackets.

A new antibacterial and fluoride-releasing bonding system consists of a self-etching primer that contains an antibacterial monomer and a bonding agent that contains sodium fluoride. This study was to determine the effect of using this new adhesive on the shear bond strength of orthodontic brackets. Forty molar teeth were randomly divided into two groups. Group 1 consisted of 20 teeth that were etched for 15 seconds with 35% phosphoric acid, washed with a water spray for 10 seconds, and dried to a chalky white appearance, and the sealant was applied to the etched surface. The precoated brackets were placed on the teeth and light cured. Group 2 consisted of 20 teeth that were etched with 35% phosphoric acid for 15 seconds as suggested by the manufacturer when bonding to intact enamel. The teeth were washed with a water spray for 10 seconds and dried to a chalky white appearance, and the primer containing antibacterial monomer was applied to the etched surface, left for 20 seconds, and sprayed with a mild airstream. The adhesive was applied to each tooth, and the precoated bracket was placed and light cured. There were no significant differences (P = .220) in the shear bond strengths of the two groups. The mean shear bond strength for the antibacterial fluoride-releasing adhesive was 11.7 +/- 5.6 MPa and for the control was 9.6 +/- 5.0 MPa. The use of an antibacterial fluoride-releasing adhesive system did not affect the shear bond strength of the orthodontic brackets within the first half hour after initial bonding.

Waterline disinfectant effect on the shear bond strength of orthodontic brackets.

The purpose of this study was to determine whether the use of an iodine compound for disinfecting the waterlines in dental units has an effect on the shear bond strength of orthodontic brackets bonded to enamel. Forty molar teeth were divided randomly into two groups- group 1 control: twenty teeth were etched for 15 seconds with 35% phosphoric acid, washed with a distilled water spray for 10 seconds, stored in distilled water for 5 minutes, dried to a chalky white appearance, and the sealant applied to the etched surface; group 2 experimental: twenty teeth were etched for 15 seconds with 35% phosphoric acid and washed for 10 seconds with water containing iodine. The teeth were stored for five minutes in the iodinated water, dried to a chalky white appearance, and the sealant applied to the etched surface as in the control group. Precoated brackets were placed on all the teeth and light cured for 20 seconds. All teeth were debonded within 30 minutes from the initial time of bonding. The t-test results (t = 1.74) indicated that there were no significant (P = .09) differences in the shear bond strengths of the teeth that were washed and immersed in the iodine solution and the control group in which distilled water was used. The mean shear bond strengths for the two groups were 6.5 +/- 3.5 MPa and 4.7 +/- 3.1 MPa, respectively.

The use of Ormocer as an alternative material for bonding orthodontic brackets.

As new adhesives, composite resins, and bonding techniques were introduced, orthodontists adopted some of these innovations and added them to their armamentarium. The purpose of this study was to compare the shear bond strength (SBS) of two adhesive materials; one with an organically modified ceramic matrix, Admira (Voco, Cuxhaven, Germany) and another that contains the traditional Bis GMA matrix namely Transbond XT (3M Unitek, Monrovia, Calif). The new materials have a lower wear rate and are more biocompatible than traditional composites. Forty molar teeth were randomly divided into two groups: 20 teeth bonded with the Transbond adhesive system and the other 20 teeth with the Admira bonding system. Student's t-test was used to compare the SBS of the two adhesives. Significance was predetermined at P < or = .05. The results of the t-test comparisons (t = 0.489) of the SBS indicated that there was no significant (P = .628) difference between the two adhesives tested. The mean SBS for Admira was 5.1 +/- 3.3 MPa and that for Transbond XT was 4.6 +/- 3.2 MPa. It was concluded that the new material, Ormocer, which is an organically modified ceramic restorative material can potentially have orthodontic applications if available in a more flowable paste. These new materials are more biocompatible and have lower wear rate including bonding orthodontic brackets to teeth.

Comparison of bonding time and shear bond strength between a conventional and a new integrated bonding system.

Conventional adhesive systems use 3 different agents, an enamel conditioner, a primer solution, and an adhesive resin during the bonding of orthodontic brackets to enamel. A characteristic of some new bonding systems is that they combine the conditioning and priming agents into a single application as well as precoat the bracket with the adhesive in an attempt to save time during the bonding procedure. This study compared the total bonding time and shear bond strength (SBS) of 2 bracket-bonding systems: (1) an integrated system that incorporates a self-etching primer and precoated brackets and (2) a conventional system in which the etchant and primer are applied separately and the adhesive applied to the bracket by the clinician. The results of the SBS and the total bonding time comparisons (t = 3.451) of the 2 adhesive systems showed a significant difference (P = .0001). The mean SBS was 9.4+/-3.7 MPa for the new bonding system and 6.2+/-4.4 MPa for the conventional system. The mean total bonding time was 36.5 s/tooth for the new system and 46.7 s/tooth for the conventional system. The clinician has to decide whether the increase in bond strength, the decrease in the total bonding time, and the steps saved during the bonding procedure with the new bonding system balance the increased cost incurred.

The effect of variation in mesh-base design on the shear bond strength of orthodontic brackets.

This study compared the shear bond strengths of two metallic orthodontic brackets, one with a single-mesh bracket base and the other with a double-mesh bracket base. The Transbond XT adhesive system was used to bond all brackets to the teeth. Two types of brackets were compared, ie, 20 Ovation metal bracket series, with a double-mesh base (Super-mesh) and an 81.50 gauge (0.126 inch), and 20 Victory series metal brackets that have a miniature single-mesh base. The teeth were bonded and debonded within half an hour from the initial bonding. The enamel surface was examined under 10x magnification to determine how much residual adhesive remained on the tooth. Student's t-test was used to compare the shear bond strength of the two groups. Chi-square test was used to compare the adhesive remnant index (ARI) scores for the two bracket types. The mean shear bond strength for the double-mesh brackets was 5.2 +/- 3.9 MPa and for the single-mesh brackets was 5.8 +/- 2.8 MPa. The t-test comparisons indicated that they were not significantly different from each other (P = .157). The ARI comparisons indicated that both bracket types had similar bracket failure modes and were not significantly different from each other (chi2 = 2.0, P = .5). These results indicated that single- and double-mesh bracket bases have comparable shear bond strength and bracket failure modes.

Retropharyngeal calcific tendonitis: report of two cases.

Retropharyngeal calcific tendonitis is an inflammatory process of the superior oblique tendons of the longus colli muscle, a neck flexor in the upper cervical spine, caused by deposition of calcium hydroxyapatite crystals; the definitive diagnostic test is computed tomography (CT). Presented in this article are two cases seen at our institution. Patients typically present with acute onset of neck pain/spasm, odynophagia, dysphagia, and/or low grade fevers. Leukocytosis and elevated erythrocyte sedimentation rate may be noted. It is important to understand this entity because its signs and symptoms are mimickers of those of the more serious condition of retropharyngeal space abscess. Calcific tendonitis is managed conservatively whereas retropharyngeal abscess requires incision and drainage. Some may argue that this entity is a zebra because its reported incidence in the literature is low. However, most of these studies were done in an era when CT was not yet in vogue. With today's widespread use of CT and its superb ability to visualize the calcification, the true incidence of this condition is probably higher and, thus, it is important for the family practitioner to be aware of this entity. The astute clinician may save the patient from unnecessary diagnostic workup, undue anxiety, and delays in hospital discharge.

Chronic addiction to dextromethorphan cough syrup: a case report.

BACKGROUND: Serious drug abuse and addiction related to dextromethorphan-containing cough preparations has been a problem in the United States since the 1950s, but few physicians are aware of it. Physicians must be alert to the type of substances and quantities used and misused by patients in obtaining a thorough routine history of over-the-counter medication use. METHODS: We describe the case of a 66-year-old clerical worker who ingested 4 to 16 oz of dextromethorphan on a regular basis over an 8-year period. We consulted with our local Poison Control Center and undertook a literature search to research previous reports of similar cases to identify the features that would aid physicians in recognition and management of this problem. RESULTS AND CONCLUSION: Despite the availability of a substantial number of case reports in specialty journals, there are almost no reports in the primary care literature of chronic dextromethorphan addiction. Our case highlights the difficulties in making an appropriate diagnosis and in obtaining effective help for the patient.

The effect of tooth bleaching on the shear bond strength of orthodontic brackets.

INTRODUCTION: The purpose of this study was to determine the effect of enamel bleaching on the shear bond strength of orthodontic brackets bonded with a composite adhesive. METHODS: Two protocols were used on 60 human molars. In the at-home bleaching group (n = 30), Opalescence bleaching agent (Ultradent, South Jordan, Utah), which contains 10% carbamide peroxide, was brushed onto the teeth daily for 14 days and left for 6 hours each day. Teeth in the in-office group (n = 30) were treated with Zoom! (Discus Dental, Culver City, Calif), which contains 25% hydrogen peroxide gel, and then exposed to a light source for 20 minutes; these teeth were treated twice. After bleaching, the specimens were randomly divided into equal subgroups and stored in artificial saliva at 37 degrees C for 7 or 14 days before bonding. Shear bond strength testing was performed on all teeth. The Kruskal-Wallis test for nonparametric means was used to determine whether significant differences existed between the various subgroups and an unbleached control group. RESULTS: The mean shear bond strength for the control group was 5.6 +/- 1.8 MPa. Means for the at-home groups were 5.2 +/- 3.6 MPa and 7.2 +/- 3.2 MPa for the 7- and 14-day waiting periods, respectively. Means for the in-office groups were 5.1 +/- 5.3 MPa and 6.6 +/- 2.6 MPa for the 7- and 14-day waiting periods, respectively. The Kruskal-Wallis test (X(2) = 8.089) indicated no significant differences between the 5 subgroups (P = .088). CONCLUSIONS: The results showed that in-office and at-home bleaching did not affect the shear bond strength of orthodontic brackets to enamel.