Quantitative evaluation of proximal tooth movement effected by wedging: a pilot study

Class II composite restoration technique teaching: A randomised controlled crossover laboratory-based trial involving a novel ringless sectional matrix technique

INTRODUCTION

Objectives were to assess how different techniques (including a novel ringless sectional matrix approach) affect students' restorative outcomes, and their preferences for and preparedness to clinically implement new techniques with the aim of introducing appropriate techniques to the undergraduate curriculum.

MATERIALS AND METHODS

Students performed two class II composite restorations in plastic teeth using two sectional matrix techniques (separating ring vs. without [ringless]), and two composite restorative techniques (incremental vs. injection-moulded bulk-fill). Restorations were assessed on multiple parameters which were combined to rate them as "good" or not. Online surveys assessed students' preferences for and preparedness to clinically implement new techniques.

RESULTS

Contact area concavity (OR = 106, p < .001) and cervical marginal overhang (OR = 7.4, p < .001) were much more likely with the separating ring compared to the ringless sectional matrix technique. "Good" restorations were 29.5 times more likely when using ringless compared to separating ring techniques and 3.3 times more likely when using the injection-moulding bulk-fill compared to layered composite technique. A majority of students preferred the ringless to separating ring sectional matrix technique and the injection-moulding bulk-fill to layered composite technique. Large majorities felt prepared to implement the new techniques clinically with no or minimal guidance.

CONCLUSIONS

A classic sectional matrix technique with separating ring resulted in a much greater occurrence of contact area concavity and cervical marginal overhang than a novel ringless approach. When allied with student preferences and clinical preparedness, inclusion of the novel ringless approach in the undergraduate curriculum can be supported alongside bulk-fill injection-moulding techniques.

Matrix transfer techniques for direct paste composite resins

This article discusses potential concerns and important considerations when selecting and using matrix transfer techniques for the direct, definitive addition of composite resin to teeth. It also provides guidance to aid these processes with the use of case studies, primarily focusing on the management of tooth wear.

Considers the advantages and disadvantages of using different matrix transfer techniques for the restoration of multiple teeth with direct paste composite.

Addresses common concerns and problems associated with using matrix transfer techniques, particularly in relation to managing the worn dentition.

Suggests guidance on selecting appropriate matrix transfer techniques to minimise complications and optimise outcomes through the exploration of case studies.

Sectional matrix solutions: the distorted truth

Sectional matrix techniques offer more predictable solutions to achieving contact areas when placing direct interproximal posterior composites than circumferential matrix techniques, resulting in reduced reported complaints of food packing from patients. Despite this, a large majority of UK dentists and therapists don't currently use them. Sectional matrix systems are technique-sensitive to use, which can be a barrier to implementation for inexperienced users. The matrices can easily distort during their placement and stabilisation and when placing the restorative material. This can result in unwanted, clinically relevant problems in the resulting restorations, some of which may not be discernible once they have occurred. This paper explores the advantages and disadvantages of sectional matrices and the processes and techniques involved in their use, before discussing the potential for distortion at each step. It offers solutions to some of the commonly seen problems which will provide more predictable outcomes for those already using these techniques and encourage non-users to add them to their armamentarium.

Extended Resin Composite Restorations: Techniques and Procedures

This article gives an overview of the state of the art of different restorative treatment procedures and techniques needed for placing extended posterior resin composite restorations. Clinical aspects related to the procedure are discussed and reviewed based on the current literature, such as the use of proper adhesive restorative materials, use of liners and bases, moisture control, reconstruction of proximal contacts, extended resin composite restorations, and techniques to address restoring teeth with deep subgingival margins.

The effect of disinfection by spray atomization on dimensional accuracy of condensation silicone impressions

BACKGROUND AND AIMS

The condensation silicone impression materials are available, but there is little knowledge of their accuracy after disinfection. The objective of this study was to evaluate the effect of the disinfection by spray atomization on dimensional accuracy of condensation silicone impressions.

MATERIALS AND METHODS

Impressions were made on a stainless steel master model containing a simulated two complete crown preparation with an edentulous space interposed using Spidex® and Rapid® impression materials. 44 impressions were made with each material, of which 16 were disinfected with 5.25% sodium hypochlorite, 16 were disinfected with 10% iodophor and 12 were not disinfected. Three dimensional measurements of working casts, including interpreparation distance, height, and diameter, were calculated using a measuring microscope graduated at 0.001 mm. Dimensional changes (mm) between the disinfected and non-disinfected working casts were compared. One-way analysis of variance (ANOVA) was employed to analyze the data (α=0.05).

RESULTS

Disinfection of each condensation silicone material by spraying atomization with two different disinfectant material resulted in significant change in interpreparation distance (p<0.05). Changes in height and diameter were only significant in Spidex® impressions (p<0.05).

CONCLUSION

Significant changes in the mean dimensions were seen as a result of disinfection by spraying; however, the dimensional changes do not seem great enough to cause critical positional distortion of teeth when fixed partial denture restorations are made.

The Influence of Matrix Type on the Proximal Contact in Class II Resin Composite Restorations

The types of matrices assessed, metal or transparent, circumferential or sectional, straight or pre-contoured, were not able to adequately reconstruct all the characteristics of the proximal contact area of an intact tooth in Class II resin composite restorations.

Accuracy of the newly formulated vinyl siloxanether elastomeric impression material

STATEMENT OF PROBLEM

A newly formulated vinyl siloxanether elastomeric impression material is available, but there is little knowledge of its accuracy in relation to existing materials.

PURPOSE

The purpose of this in vitro study was to assess the accuracy of disinfected vinyl siloxanether impressions and compare the accuracy to a common vinyl polysiloxane and a polyether impression system.

MATERIAL AND METHODS

Impressions were made from a modified dentoform master model containing a simulated crown preparation. Dimensional changes (mm) between the master model and working casts (type IV gypsum) were assessed. The following were evaluated: vinyl polysiloxane in a 1-step, dual-viscosity technique (VPS Dual), polyether as monophase material (PE Mono), and vinyl siloxanether in a 1-step, dual-viscosity (VSE Dual), and monophase technique (VSE Mono). Measurements of the master model and working casts, including anteroposterior (AP) and cross-arch (XA) dimensions, were made with a measuring microscope. The simulated crown preparation was measured in mesiodistal (MDG, MDO), buccolingual (BLG, BLO), and occlusogingival dimensions (OGL, OGB). Disinfection involved immersion for 10 minutes in potassium peroxomonosulfate, sodium benzoate, tartaric acid solution, or no disinfection (control) (n=8). A multivariate GLM statistical approach (MANOVA) was used to analyze the data (alpha=.05). Pearson's correlation test was used for related dimensions.

RESULTS

The AP and XA dimensions of working casts were larger than the master for the disinfected condition and control. Whether disinfected or not, the working dies were shorter in height (OGB, OGL), larger in the buccolingual dimension (BLO, BLG), somewhat larger in the MDO dimension, and somewhat smaller in the MDG dimension compared to the prepared tooth of the master model, resulting in an irregular or oval profile. There were significant differences among the impression systems for each dimension except AP. Differences between the disinfected and nondisinfected conditions were significant (P=.03) with respect to dimensions of the gypsum working cast, but not for dimensions of the working die (P=.97). In general, differences relative to the master were small and of minor clinical significance considering marginal gaps of crowns smaller than 150-100 mum are considered clinically acceptable.

CONCLUSIONS

VSE monophase impressions and VSE dual-viscosity impressions demonstrated acceptable accuracy for clinical use with immersion disinfection, since the results for VSE were comparable to the results for PE and VPS materials, and the differences as compared to the master model were small.

Accuracy of a new ring-opening metathesis elastomeric dental impression material with spray and immersion disinfection

STATEMENT OF PROBLEM

A new elastomeric impression material has been formulated with a ring-opening metathesis chemistry. In addition to other properties of clinical significance, the impression accuracy must be confirmed.

PURPOSE

The purpose of this study was to compare the accuracy of the new elastomeric impression material with vinyl polysiloxane and polyether following both spray and immersion disinfection.

MATERIAL AND METHODS

Impressions of a modified dentoform with a stainless steel crown preparation in the lower right quadrant were made, and type IV gypsum working casts and dies were formed. Anteroposterior (AP), cross-arch (CA), buccolingual (BL), mesiodistal (MD), occlusogingivobuccal (OGB), and occlusogingivolingual (OGL) dimensions were measured using a microscope. Working cast and die dimensions were compared to those of the master model. The impression materials were a newly formulated, ring-opening metathesis-polymerization impression material (ROMP Cartridge Tray and ROMP Volume Wash), vinyl polysiloxane (VPS, Aquasil Ultra Monophase/LV), and a polyether (PE, Impregum Penta Soft/Permadyne Garant L). Fifteen impressions with each material were made, of which 5 were disinfected by spray for 10 minutes (CaviCide), 5 were disinfected by immersion for 90 minutes (ProCide D), and 5 were not disinfected. There were significant cross-product interactions with a 2-way ANOVA, so a 1-way ANOVA and Dunnett's T3 multiple comparison test were used to compare the dimensional changes of the 3 impression materials, by disinfection status and for each location (alpha=.05).

RESULTS

For ROMP, there were no significant differences from the master, for any dimension, when comparing the control and 2 disinfectant conditions. No significant differences were detected among the 3 impression materials for CA, BL, and MD. The working die dimensions of OGB and OGL for VPS with immersion disinfection were significantly shorter than with PE and ROMP (P<.05). Overall, the AP dimension was more accurate than CA, and the BL of working dies was 0.040 mm greater in diameter than MD.

CONCLUSIONS

The accuracy of gypsum working casts and working dies from the new and 2 existing types of impression material were similar, for both spray and immersion disinfection. Judicious application of a die spacer can compensate for the small differences observed. VPS may require additional laboratory accommodation to compensate for a shorter working die.

A clinical study on interdental separation techniques

The effect of interdental separation of a special separation ring and wooden wedge was investigated. In a split-mouth design, 27 patients were randomly assigned to one of two groups (W or S). In 11 patients, an interdental wooden wedge (Hawe-Neos) was placed (group W), and in 16 patients, a separation ring (Composi-Tight Gold) was placed at the contact between teeth 4/5 and 5/6. Simultaneously, in both groups, a wooden wedge, combined with a separation ring (Composi-Tight Gold), was placed on the contact between teeth 4/5 and 5/6 (reference group W+S). To measure proximal contact tightness, frictional forces were recorded at the removal of a 0.05 mm thick metal matrix band inserted between adjacent teeth. Contact tightness was measured at contacts 4 and 5 and at 5 and 6 in the third and fourth quadrant using the Tooth Pressure Meter prior to applying separation devices (TO) five minutes after application (T1) and five minutes after removal of the devices (T2). The effect of separation was determined by calculating the differences between contact tightness before application and contact tightness with the devices in situ (T1-T0). Interdental recovery was calculated by the difference in contact tightness before application and after removal of the devices (T2-T0). To assess the presence of statistically significant differences between these measurement times, paired t-tests were applied. With each patient, either a comparison between W and W+S or S and W+S was made. For both W versus W+S and S versus W+S, paired t-tests were applied to compare differences (T1-T0 and T2-T0) between the separation devices. Within a patient, groups W and S could not be compared, therefore, to compare separation achieved between these two devices, unpaired t-tests were used. The increase in contact tightness measured at contact 4 and 5 for group W (0.98 +/- 0.26 N) was statistically significantly less compared to the increase in group S (5.48 +/- 0.88 N) (p < 0.001) or group W+S (4.62 +/- 0.68 N) (p = 0.02). No significant differences were found between groups S and W+S (p = 0.77). For all groups, five minutes after removal of the devices, the contact tightness at contact 4 and 5 and at contact 5 and 6 were still significantly weaker compared to the tightness at baseline (p < 0.02). When separation is required for restorative procedures, such as at placement of a Class II resin composite restoration, special separation rings may be more useful than wooden wedges.

Accuracy of newly formulated fast-setting elastomeric impression materials

STATEMENT OF PROBLEM

Elastomeric impression materials have been reformulated to achieve a faster set. The accuracy of fast-setting elastomeric impression materials should be confirmed, particularly with respect to disinfection.

PURPOSE

The purpose of this study was to assess the accuracy of 2 types of fast-setting impression materials when disinfected with acid glutaraldehyde.

MATERIAL AND METHODS

Impressions of the mandibular arch of a modified dentoform master model were made, from which gypsum working casts and dies were formed. Measurements of the master model and working casts included anteroposterior (AP) and cross-arch (CA) dimensions. A stainless steel circular crown preparation incorporated within the master model was measured in buccolingual (BL), mesiodistal (MD), and occlusogingival (OG) dimensions and compared to measurements from recovered gypsum dies. The impression materials examined were a fast-set vinyl polysiloxane (VPS-FS, Aquasil Ultra Fast Set), a fast-set polyether (PE-FS, Impregum Penta Soft Quick Step), and a regular-setting polyether as a control (PE, Impregum Penta). Disinfection involved immersion in 3.5% acid glutaraldehyde (Banicide Advanced) for 20 minutes, and nondisinfected impressions served as a control. Linear measurements were made with a measuring microscope. Statistical analysis utilized a 2-way and single-factor analysis of variance with pair-wise comparison of mean values when appropriate. Hypothesis testing was conducted at alpha = .05

RESULTS

No differences were shown between the disinfected and nondisinfected conditions for all locations. However, there were statistical differences among the 3 materials for AP, CA, MD, and OG dimensions. AP and CA dimensions of all working casts were larger than the master model. Impressions produced oval-shaped working dies for all impression materials. PE and PE-FS working dies were larger in all dimensions compared to the stainless steel preparation, whereas VPS-FS-generated working dies were reduced in OG and MD dimensions. Differences detected were small and may not be of clinical significance.

CONCLUSIONS

Impression material accuracy was unaffected by immersion disinfection. The working casts and dies were similar for PE and PE-FS. VPS-FS generated gypsum dies that were smaller in 2 of the 3 dimensions measured and may require additional die relief. Overall accuracy was acceptable for all 3 impression materials.

Clinical testing of restorative materials: some historical landmarks

OBJECTIVES

The aim of the study was to review the historical background of the methodologies currently in use for clinical investigations of contemporary tooth coloured dental restorative materials and techniques, and to attempt to identify the likely general direction of such research projects in the future.

DATA SOURCES

Published articles obtained as a result of a wide ranging literature search of both dental and medical journals.

STUDY SELECTION

Historical and contemporary accounts of clinical trial management, upon which an overview of the key events important in the evolution of clinical methods of evaluation of dental restorative materials, and a prediction of possible future trends in this area, could be based.

CONCLUSIONS

Publication of dental restoratives clinical research has not kept up with that in medicine, where editors of leading journals require that clinical trials be run in accordance with the Consolidated Standards of Reporting Trials (CONSORT) guidelines. The current trend towards evidence based treatment in dentistry can be expected to initiate more statistically powerful clinical studies of dental restoratives, and the merit of involving general dentists in practice based research can also be anticipated to become increasingly recognised in the future.

An accuracy evaluation of four removable die systems

STATEMENT OF PROBLEM

The advent of implant dentistry has redefined the need for accuracy of working cast models. Die stone expansion and errors introduced by removable die casts may exceed the accuracy required for the passive fit of implant prostheses.

PURPOSE

Several removable die systems claim improved accuracy because of their design and/or technical advancements. This study evaluated the 3-dimensional accuracy of 4 removable die systems. All 4 systems tested use either 1 or 2 pins as the repositioning device.

MATERIAL AND METHODS

Four removable die systems were evaluated (Belle de St. Claire, Pindex, DVA, and conventional brass dowel system). Master model impressions were made with polyvinyl siloxane material and were later cast with type IV die stone material. Comparative dimensional analysis between the master model and the solid and sectioned casts was made by placing the cast in a standardized position and fabricating an individual custom base for each cast. Landmarks were measured with a traveling microscope, and by mathematically rotating the casts. Discrepancies beyond that of stone expansion or residual stress release at the time of die separation were due to the inability to precisely reposition the removable die of the sectioned cast. Data were analyzed with multivariate analysis of variance and paired t tests at alpha = .05 (n = 10).

RESULTS

Significant differences were found among die systems tested (P = .005). When sectioned dies were compared with the master model, the accuracy of all 4 die systems was within 0.055 mm of the master model. Once sectioned, the Pindex system had the least linear expansion in the y dimension, and the brass dowel system demonstrated the least reseating discrepancy in the z (occlusogingival) dimension.

CONCLUSIONS

All 4 die systems provided a similar degree of dimensional accuracy, although Pindex showed the least horizontal movement and the brass dowel system produced the least occlusogingival reseating discrepancy.

Dimensional stability and detail reproduction of irreversible hydrocolloid and elastomeric impressions disinfected by immersion

STATEMENT OF PROBLEM

Because irreversible hydrocolloid impressions imbibe blood and saliva, immersion rather than spray disinfection may be more effective. Polyether has been shown to be dimensionally sensitive to immersion disinfection.

PURPOSE

The aim of this study was to determine whether irreversible hydrocolloid and polyether impressions could be disinfected by immersion without sacrificing accuracy and surface quality.

MATERIAL AND METHODS

Impressions were made of a master mandibular arch containing a crown preparation. Changes between the master and working casts were assessed. Irreversible hydrocolloids (Jeltrate; Palgaflex), a polyether (Impregum F), and an addition silicone (President) were used. Disinfectants were an iodophor (Biocide), a glyoxal glutaraldehyde (Impresept de), and a phenol glutaraldehyde (Sporicidin). The control was without disinfection. Casts were formed in Type IV gypsum. The roughness of working dies was also recorded and an analysis of variance was used for statistical evaluation. Results. Casts from disinfected irreversible hydrocolloid and elastomeric impressions maintained accuracy for anteroposterior and cross arch dimensions where differences from the master was less than 0.1%. Buccolingual and mesiodistal dimensions of working dies (disinfected and control) were 6 to 8 microm larger than the master for addition silicones and 11 to 16 pm for polyethers. The occlusogingival dimension of dies for control and disinfected polyether was 9 pm longer than the master compared with -3 microm for addition silicone. The range of mean surface roughness of working dies made from irreversible hydrocolloids was 1.4 to 1.7 microm and ranged from 0.5 to 0.7 microm for elastomeric impressions. Conclusion. Immersion disinfection of Jeltrate material with iodophor and Palgaflex material with glyoxal glutaraldehyde produced casts and dies as accurate as the control. Control and disinfected elastomeric impression produced dies as clinically accurate and smooth as the master. Disinfection of irreversible hydrocolloid impressions with the glyoxal and phenol glutaraldehyde produced a surface smoother than controls.

Accuracy and bond strength of reversible with irreversible hydrocolloid impression systems: a comparative study

Combinations of three reversible hydrocolloids with five irreversible hydrocolloids were evaluated for dimensional accuracy and bond strength. A stainless steel model representing two teeth prepared for a fixed partial denture was designed for an accuracy study. The recordings were made with a measuring microscope, and the tensile bond strength was determined with an Instron Universal Testing instrument. The accuracy of these materials was clinically acceptable, and the resulting models were suitable. The materials distributed by a common supplier exhibited better tensile strength, although one irreversible hydrocolloid, Jeltrate, performed well in the noncompanion combination groups. This reversible with irreversible hydrocolloid combination impression has an advantage compared with the traditional reversible hydrocolloid impression, because it does not require elaborate, expensive conditioning equipment and water cooled trays.

Accuracy and dimensional stability of a combined hydrocolloid impression system

The accuracy of a combined hydrocolloid impression system was studied as a function of time of pour. There was little change in dimension between posts for all time intervals studied. No statistically significant differences were noted among the observation periods until 3 hours. The results indicate that for the impression system studied, a 3-hour pouring time can be used for transport to a commercial dental laboratory, provided the impressions are stored in 100% relative humidity. The hydrocolloid impression system tested resulted in a stone cast of slightly deviating dimensions compared with the master model. Therefore laboratory procedures should compensate for cement thickness, taking into account the minimal changes in dimensions of the die.

Accuracy of elastomeric impressions disinfected by immersion

This study evaluates the accuracy and surface quality of stone dies made from impressions that had been placed in disinfectants. Results indicated that selection of the type of impression material is more important than selection of the disinfectant. Addition silicone and polysulfide impressions were disinfected without a loss in accuracy, whereas polyether impressions were adversely affected. The surface quality of dies was acceptable with disinfection and one disinfectant contributed to an improvement in surface quality compared with the control.

A hybrid matrix retainer for two-surface proximal restorations

A hybrid matrix combines the rigid and flexible properties of two different thicknesses of matrix bands for use in restoring the proximal surfaces of teeth.