A split-mouth randomized clinical trial of single crowns retained with resin-modified glass-ionomer and zinc phosphate luting cements

PURPOSE: This study compared the influence of two luting cements on the clinical performance of single crowns. MATERIALS AND METHODS: Twenty patients received 39 pairs of metal-ceramic and Procera crowns cemented with zinc phosphate and resin-modified glass-ionomer luting cement (Vitremer) in a split-mouth randomized pattern blinded to the recipient. The crowns were examined immediately after cementation, after 2 weeks, after 6 months, and then yearly. Clinical performance was scored according to CDA criteria, Silness and Loe criteria, patient satisfaction, and operator-appraised general clinical criteria. Three clinicians in private general practice carried out all procedures. RESULTS: During the observation period, which varied between 80 and 104 months, seven clinical events were recorded. Two abutments fractured vertically, two underwent retrograde endodontic surgery, and one developed pulp necrosis. Two crowns were recemented. Estimated survival, defined as no negative events observed, was 89% at 102 months (85% for crowns cemented with zinc phosphate and 93% for crowns cemented with resin-modified glass-ionomer). Estimated survival, defined as no recementation or loss of pulp vitality, was 96% at 102 months (95% with zinc phosphate and 97% with resin-modified glass-ionomer). The differences between cements were not statistically significant. CONCLUSION: A resin-modified glass-ionomer luting cement was at least as good as zinc phosphate cement to retain single crowns over a 102-month observation period.     

A comparative clinical trial of a glass ionomer and a zinc phosphate cement for securing orthodontic bands

This is a report of a clinical trial, comparing an experimental glass ionomer luting cement with a zinc phosphate cement for securing orthodontic bands. The comparison was made by using survival analysis techniques. The glass ionomer cement performed significantly better than the zinc phosphate cement.     

Use of zinc phosphate cement as a luting agent for Denzir trade mark copings: an in vitro study

BACKGROUND: The clinical success rate with zinc phosphate cemented Procera crowns is high. The objective with this study was to determine whether CADCAM processed and zinc phosphate cemented Denzir copings would perform as well as zinc phosphate cemented Procera copings when tested in vitro in tension. METHODS: Twelve Procera copings and twenty-four Denzir copings were made. After the copings had been made, twelve of the Denzir copings were sandblasted on their internal surfaces. All copings were then cemented with zinc phosphate cement to carbon steel dies and transferred to water or artificial saliva. Two weeks after cementation, half of the samples were tested. The remaining samples were tested after one year in the storage medium. All tests were done in tension and evaluated with an ANOVA. RESULTS: Sandblasted and un-sandblasted Denzir copings performed as well as Procera copings. Storage in water or artificial saliva up to one year did not decrease the force needed to dislodge any of the coping groups. Three copings fractured during testing and one coping developed a crack during testing. The three complete fractures occurred in Procera copings, while the partly cracked coping was a Denzir coping. CONCLUSION: No significant differences existed between the different material groups, and the retentive force increased rather than decreased with time. Fewer fractures occurred in Denzir copings, explained by the higher fracture toughness of the Denzir material. Based on good clinical results with zinc phosphate cemented Procera crowns, we foresee that zinc phosphate cement luted Denzir copings are likely to perform well clinically.     

A prospective multicenter randomized clinical trial of autogenous bone versus beta-tricalcium phosphate graft alone for bilateral sinus elevation: histologic and histomorphometric evaluation

PURPOSE: Two different graft materials, beta-tricalcium phosphate (Cerasorb) and autogenous bone, were used in the same patient. The objective was to determine whether donor site morbidity could be avoided by using pure-phase beta-tricalcium phosphate (Cerasorb). MATERIALS AND METHODS: Bilateral sinus grafting was performed on 20 selected patients; Cerasorb was used on the experimental side, and autogenous bone was used on the control side. In each patient, one side was randomly designated the experimental side. In 10 of the 20 patients, the maxilla reconstruction included sinus grafting and onlay bone grafting. Implants were placed 6 months after the procedure. In addition to routine panoramic radiographs, in 10 of the 20 patients, 2- and 3-dimensional computerized tomographic examinations were performed pre- and postoperatively and after implantation. Eighty bone biopsy specimens were taken at the time of implant placement. RESULTS: Histologically and histomorphometrically, there was no significant difference between the experimental and control grafts in terms of the quantity and rate of ossification. For each histologic sample, the total surface area, the surface area that consisted of bone, and the surface area that consisted of graft material were measured in mm2, and bone and graft material were analyzed as percentages of the total. The mean percentage bone areas were 36.47% +/- 6.9% and 38.34% +/- 7.4%, respectively; the difference was not significant (P = .25). DISCUSSION AND CONCLUSION: Comparisons with other studies reveal that beta-tricalcium phosphate (Cerasorb) is a satisfactory graft material, even without autogenous bone.     

A practice-based evaluation of the handling of a new self-adhesive universal resin luting material

OBJECTIVE: Ease of handling of materials may be considered helpful to achieving good results. The handling properties of a new self-adhesive universal resin luting material were tested in clinical use. METHOD AND MATERIAL: Thirteen practitioners were selected at random from the Product Research and Evaluation by Practitioners (PREP) Panel, a United Kingdom-based group of dental practitioners prepared to complete evaluations of new materials and techniques in the practice environment. Explanatory letters, questionnaires and packs of the luting material were sent to the evaluators. The practitioners were asked to use the material and return the questionnaire. RESULTS: 144 restorations were placed using the new self-adhesive resin luting material, which was rated higher by the evaluators for ease of use (4.7 on a visual analogue scale where 5 represented easy to use and 1 represented difficult to use) than both the pre-trial resin-based and 'conventional' luting materials (rated 3.7 and 4.4 respectively on the same scale). The presentation, instructions, convenience of dispensing and handling and viscosity also received high ratings. CONCLUSION: The new material achieved ratings for ease of use superior to the pre-study resin-based and conventional luting materials in the dental practices of 13 UK dental practitioners.     

Transmitted irradiance through ceramics: effect on the mechanical properties of a luting resin cement

Objectives

The study aims to characterise the curing behaviour of a light-curing luting composite (Variolink® Aesthetic LC, Ivoclar Vivadent) polymerised at different exposure times (10 s, 20 s) through different ceramics (IPS Empress CAD and IPS e.max CAD, Ivoclar Vivadent) and ceramic thicknesses (no ceramic, 0.5, 1, 1.5 and 2 mm).

Material and method

Curing units’ (Bluephase Style, Ivoclar Vivadent) variation in irradiance delivered up to 10-mm exposure distance as well as the incident and transmitted irradiance and radiant exposure up to 6-mm ceramic thickness were assessed on a laboratory-grade spectrometer. A total of 216 (18 groups, n = 12) thin and flat luting composite specimens of 500-μm thickness were prepared and stored after curing in a saturated vapour atmosphere for 24 h at 37 °C. Micro-mechanical properties (Vickers hardness, HV and indentation modulus, Y_HU) were determined by means of an automatic micro-hardness indenter.

Results

Within the study design, the radiant exposure received by the luting composite varied from 2.56 to 24.75 J/cm², showing a high impact on the measured properties. Comparing the effect of the parameters exposure time, ceramic thickness and type, the highest influence on the micro-mechanical parameters was identified for exposure time, while this influence was stronger on HV (p < 0.001, η _P ² = 0.452) than on Y_HU (p < 0.001, η _P ² = 0.178). The influence of ceramic type was significant but low (η _P ² = 0.161 on HV and 0.113 on Y_HU), while the influence of ceramic thickness was the lowest (η _P ² = 0.04 and 0.05, respectively).

Conclusions

Slightly higher irradiance values were transmitted through Empress CAD up to a ceramic thickness of 3 mm (p < 0.001), while being comparable with e.max for thicker slices. Differences in translucency between ceramics were reflected in the micro-mechanical properties of the luting composite.

Clinical relevance

The radiant exposure reaching the luting composite is determined by the incident irradiance, exposure time, ceramic type and ceramic thickness. At the analysed incident irradiance, exposure time was the most consistent parameter affecting the micro-mechanical properties of the luting composite, and this effect was strongly reflected in the more translucent ceramic Empress CAD. Within the curing conditions, an exposure time of 20 s is recommended.

     

A comparison between zinc phosphate and glass ionomer cement in orthodontics

In the past orthodontic band cementation has relied heavily on mechanically retentive cements such as zinc phosphate luting agents. The clinical performance of a glass ionomer cement (GIC), a chemically retentive cement, was evaluated against a conventional zinc phosphate cement (ZP). The recementation values for ZP were significantly higher over a 2-year treatment period than those of GIC. Failures between cement and enamel, and cement and stainless steel were noted for the ZP. Glass ionomer cement had significantly better retentive strength to enamel than to band material. Moisture contamination does not appear to be a problem in orthodontic band cementation with glass ionomer cement.     

Transmandibular implant versus intramobile cylinder implants: a randomized, prospective clinical trial

A randomized, controlled clinical trial was conducted to compare two different implant treatment modalities for edentulous patients with severely resorbed mandibles. In one modality (the IMZ^® group), two intramobile cylinder implants were placed, connected by a Dolder bar and provided with an overdenture, and in the other (the TMI group), a transmandibular implant with a triple bar and cantilever extensions was placed, likewise provided with an overdenture. The conditions of the overdentures, the peri-implant tissues, and the implants were evaluated. Orthopantomograms were taken for radiologic evaluation. An overal complication scale which took account of all aspects was devised to compare the results. The follow-up period was 2–4 years, with a mean follow-up of 3 years. The condition of dentures and oral hygiene aspects were comparable for both groups. The complication rate in the TMI group was significantly higher than that in the IMZ group. The scores on the complication scale resulted in a significant difference between the TMI and the IMZ groups (Wilcoxon, P=0.0044).