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C H Pameijer

Publications and source records attributed to C H Pameijer.

At least 19 recordsLinked to original sources
PubMed2006

Retreatment efficacy of hand versus automated instrumentation in oval-shaped root canals: an ex vivo study.

AIM: To compare the efficacy of hand versus automated instrumentation when retreating oval-shaped root canals. METHODOLOGY: Sixty human premolars with single oval canals were instrumented and filled with gutta-percha and sealer and divided into three groups (n = 20)--group 1: ProFile .04 taper rotary instruments; group 2: Anatomic Endodontic Technology (AET), and group 3: manual instrumentation with Hedström files. The teeth were split longitudinally and gutta-percha/sealer remnants in the coronal, middle and apical thirds were assessed with light microscopy. The mean percentage of gutta-percha/sealer remnants for each group was calculated and statistically analysed for significance using an ANOVA repeated measures (P < 0.001) and Tukey's multiple comparison test. The time required for retreatment was analysed using a one-way ANOVA and Tukey's test (P < 0.001). RESULTS: Overall, 10-18% of the canal walls were covered with gutta-percha/sealer remnants after preparation using any technique. Statistical analysis demonstrated that the mean values for remnants of filling material in the ProFile group were significantly higher than for the other groups (P < 0.001), except in the apical third where no significant difference occurred. In all groups, the mean values in the middle third were higher than the coronal and apical thirds. The retreatment time for ProFile and AET was significantly shorter compared to manual instrumentation with Hedström files (P < 0.001). CONCLUSIONS: Under the experimental conditions, AET instruments and manual instrumentation with Hedström files resulted in cleaner canals. However, completely clean root canal walls were not produced with any of the techniques investigated.

Bicuspid↗
PubMed2005

Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic study.

AIM: To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation. METHODOLOGY: Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at x200 and x400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 mum square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal-Wallis nonparametric anova and Dunn's tests. RESULTS: At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups. CONCLUSIONS: Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated.

Analysis of Variance↗
PubMed2004

Volumetric polymerisation shrinkage of different dental restorative materials.

STATEMENT OF PROBLEM: Polymerisation shrinkage is a critical limitation of dental resins and may contribute to micro leakage. PURPOSE: The purpose of this study is to record and compare volumetric changes of various dental composites and compomers, exposed for 40 seconds to a commercial halogen light source. MATERIAL AND METHODS: Eleven light-polymerised composites and compomers were evaluated using a dilatometer that recorded the polymerisation shrinkage every 0.5 second. The mercury column pressure was measured electronically with a pressure-sensitive transducer, and the data recorded and stored in a computer. The computer also recorded the temperature, controlled the light-source and displayed the data in graphic format. Every material was tested ten times. The data were analysed by means of an ANOVA (P < 0.05). RESULTS: A high rate of shrinkage occurred for all materials in the first ten seconds of polymerisation. Surefil showed the lowest rate while TPH displayed the highest. Of the higher filled materials, Surefil (0.96%) showed the least shrinkage, followed by Z250 (0.99%), Dyract AP (1.18%), Herculite (1.27%), Compoglass (1.32%), Amelogen (1.34%) and TPH-Spectrum (1.6%). Overall, the flowable materials exhibited significantly more shrinkage (P < 0.05). For this group Compoglass Flow (2.3%) showed the least shrinkage followed by Filtec Flow (2.31%). Permaflo (3.6%) exhibited the most shrinkage followed by Dyract Flow (3%). CONCLUSION: Within the limitations of this study, it is concluded that significant differences exist among the polymerisation shrinkage of the most resins tested. An increase in the filler content of a material significantly lessens the polymerisation shrinkage while an increase in the monomer concentration causes significantly more polymerisation shrinkage. CLINICAL SIGNIFICANCE: The more flowable a composite material becomes, the more the restoration will shrink. Clinicians should take this into account when they decide on cavity design and materials to use.

Analysis of Variance↗
PubMed2002

Pulp histology after Er:YAG laser cavity preparation in subhuman primates--a pilot study.

UNLABELLED: The aim of the study was to make a direct comparison of the pulpal effects of laser and turbine preparations in subhuman primates. One female baboon (Papio Ursinus ursinus), weighing 15 kg, was used. General anaesthesia was administered (ketamine 100 mg/ml/kg body weight) and maintained with acepromazine (10 mg/ml/kg body weight). Class V cavities were prepared buccally in a total of 28 teeth (7 in each quadrant). Teeth in the upper right and lower left quadrants were prepared using a conventional 330 carbide bur in a high-speed fibre-optic handpiece with copious water spray. Teeth in the upper left and lower right quadrants were prepared using an Er:YAG laser drill (Fotona Twinlight, Llubljana, Slovenia) delivering 500 mJ at a pulse rate of 10 Hz and a wavelength of 2940 nm. The animal was sacrificed after 25 days. After general anaesthesia as described before, perfusion fixation of the head was accomplished with 10% neutral buffered formalin, pumped through a catheter inserted into the left carotid artery. The jaws were removed and, using a 330 carbide bur in a high speed handpiece, a continuous groove was cut through the bone and the roots at the level of the middle third of all the roots to promote thorough fixation of pulpal tissue. Decalcification and grading of the severity of the pulpal responses were conducted according to standard procedures. RESULTS: Owing to procedural errors seven teeth, FDI numbers 23, 24, 31, 34, 35, 44 and 45, had to be eliminated. The turbine-prepared teeth (N = 11) had a mean remaining dentine thickness (RDT) of 0.77 mm (SD = 0.42) and the laser-prepared teeth (N = 10) had a mean RDT of 0.81 mm (SD = 0.60). All pulps appeared normal except in one turbine-prepared tooth (12 with RDT = 0.20) and one laser-prepared tooth (27 with RDT = 0.30, where irreversible damage was caused. The only other deviations from normal were seen in the laser-treated 41 (RDT = 0.69) and the turbine-treated 36 (RDT = 0.77) where moderate hyperaemia was seen. Within the limitations of this study it can be concluded that there is no significant difference between dental pulp of teeth where Class V cavities were prepared with an Er:YAG laser drill compared with those prepared with a standard turbine drill.

Animals↗
PubMed2001

Effect of carbamide peroxide bleaching agents on the physical properties and chemical composition of enamel.

PURPOSE: To evaluate the effect of two commercially available carbamide peroxides bleaching agents, Opalescence and Nite-White, in concentrations of 10, 15 and 16%, on enamel. MATERIALS AND METHODS: Vickers hardness measurements (VH) were made at the surface and 110 microns below the surface on human enamel samples that were treated for 5 or 10 days, 6 hrs/day. Furthermore, infrared spectrophotometry (IR), Fourier transform infrared spectrophotometer (FTIR) and X-ray diffraction (XRD) measurements were performed after the VH measurements were completed. RESULTS: Using a one-way ANOVA, statistically significant differences in VH could be established between surface and subsurface VH values. For all groups, including the control group, the surface VH values were statistically significantly higher than subsurface VH. IR, FTIR and XRD established a change from hydroxyapatite to primary calcium ortho phosphate [Ca(H2PO4)2] for all experimental groups except for 10% Opalescense tested for 5 or 10 days.

Analysis of Variance↗
PubMed2001

Pulp capping with a modified bioglass formula (#A68-modified).

PURPOSE: To evaluate a modified Bioglass (Formula #68 (MBF68) when used as a pulp capping agent. MATERIALS AND METHODS: After exposure, the pulps were contaminated with saliva for 60s, rinsed, dried and treated with Consepsis, acting as a hemostatic and bactericidal agent. After drying the Consepsis, the MFB68, having been pre-mixed in sterile saline, was carefully deposited over the pulp exposure, covered with polycarboxylate cement and restored with the ProBond bonding resin system. A calcium hydroxide group was used as control. RESULTS: There was no evidence of mummification, the incidence of properly positioned dentin bridge formation was higher and the incidence of extruded dentin bridge formation was reduced.

Animals↗
PubMed1998

Retention of parallel-sided titanium posts cemented with six luting agents: an in vitro study.

PURPOSE: This in vitro study compared the effectiveness of 6 luting systems on the retention of prefabricated titanium posts. MATERIAL AND METHODS: A total of 120 single-rooted teeth were sectioned at the cementoenamel junction and treated endodontically. Roots were mounted in copper cylinders, and prefabricated, parallel-sided titanium posts were cemented according to the manufacturer's instructions. Two resin-ionomer hybrid cements and 2 resin cements were tested with corresponding dentin bonding agents. A glass ionomer cement was also tested, and zinc-phosphate cement served as the control. Samples were tested in an Instron universal testing machine to catastrophic tensile failure. RESULTS: Advance cement with Prime and Bond systems was found to be statistically more retentive than all other groups tested (P < .05). Cement It with Bond It and Permalute with Permalute Primers A and B systems demonstrated significantly greater retention than Ketac Cem cement, Resinomer with One-Step system and zinc-phosphate cement (P < .05). There was no statistically significant difference among Ketac Cem cement, Resinomer with One-Step system, and zinc-phosphate cement.

Analysis of Variance↗
PubMed1998

The disastrous effects of the "total etch" technique in vital pulp capping in primates.

PURPOSE: To determine by means of a histopathological study in sub-human primates whether etching of an exposed pulp (the "Total Etch" technique) followed by capping with dentin bonding agents is a viable clinical treatment modality. MATERIALS AND METHODS: In six sub-human primates, 147 Class V preparations were made for five experimental and two control groups. After exposing the pulps, the preparations were intentionally contaminated, rinsed, dried and then disinfected with a 2% chlorhexidine solution for 60 s. In the five experimental groups, the entire preparation including the exposed pulp was etched with a 35% phosphoric acid gel, which was rinsed after 20 s. This was followed by a second application of chlorhexidine. In Groups 1-3, All Bond 2, ProBond and Permagen A&B dentin bonding agents were applied as pulp capping materials. In Group 4, a light-cured calcium hydroxide was tested while Group 5 was treated with a chemically-cured calcium hydroxide. Groups 6 and 7, the controls, were also contaminated, rinsed, dried and disinfected. After the exposed pulps had been protected with a chemically-cured calcium hydroxide (Group 6) or a light-cured calcium hydroxide (Group 7) the preparations were etched and restored with a bonded resin composite. The effect of the above described treatments were evaluated at 5, 25 and 75 days. After sacrifice and routine histological preparation, histological sections were graded among other parameters for inflammatory response, bridge formation, maintenance of vitality, presence of dentin chips and evidence of microleakage microorganisms. RESULTS: The 2% chlorhexidine applied immediately after exposure was an effective hemostatic agent. After subsequent etching, the hemostatic effectiveness was greatly reduced. Exposure size for all seven groups ranged from 0.13-1.55 mm. The average at 5, 25 and 75 days measured 0.74, 0.66 and 0.77 mm, respectively. In the five experimental groups, the 25- and 75-day groups had a total of 68 teeth of which 24 (35%) became non-vital and 23 (33%) teeth demonstrated bridge formation. In the three experimental groups using a bonding agent, the 25- and 75-day groups had a total of 40 teeth of which 18 (45%) became non-vital and 10 (25%) exhibited bridge formation. In the "No Etch" control groups, the 25- and 75-day groups had 28 teeth of which two (7%) became non-vital and 23 (82%) exhibited bridge formation. Microorganisms were found in a large percentage of all groups, although their numbers were few. However, they were present in vital and non-vital teeth, in the presence and absence of bridge formation and had no direct bearing on the success or failure of the pulp capping procedure.

Acid Etching, Dental↗
PubMed1997

Adherence of "stuck" restorations to demineralized dentin following use of experimental primers.

PURPOSE: This in vivo study histopathologically evaluated the biocompatibility of four self-conditioning dentinal primer formulas in four bonding systems and evaluated the pulpal responses of the self-conditioning dentinal bonding systems for Class V tooth preparations in primates. MATERIAL AND METHODS: The basic formula consisted of proprietary carboxylic diacid monomer, dipentaerythritol pentaacrylate phosphoric acid ester, acetone, and ethanol that was used alone or mixed with other commercial priming agents. After application of primers, Prisma Universal Bond 3 was selected to restore the cavity preparations. RESULTS: All systems were judged histopathologically biocompatible. "Stuck" restorations that were resistant to acid demineralization necessary for processing of histologic slides, occurred more frequently with intact smear layers and increasing use of dehydrating agents. CONCLUSIONS: Tests should be performed to determine whether "stuck" restorations in in vivo studies that maintain dentin-pulpal relationships can support in vitro shear bond strength tests.

Acetone↗
PubMed1997

Significance of pulpal pressure during clinical bonding procedures.

PURPOSE: To determine whether pulpal pressure in vital teeth plays a significant role in dentin bonding procedures. MATERIALS AND METHODS: Half the teeth in three baboons received root canal treatment thus eliminating pulpal pressure. All teeth were then prepared on the buccal surface with a diamond wheel to create flat surfaces into dentin, measuring at least 4 mm in diameter. Dentin bonding systems from two manufacturers were applied. Using a Bencor tensile nozzle freehand, 3.5 mm diameter composite buttons were bonded to the prepared surfaces. The animals were sacrificed 24 hours later, the teeth removed and mounted in specimen rings, using the same Bencor tensile nozzle for proper axial alignment. The composite buttons were tested for shear bond strength in a tensometer. RESULTS: The results showed no statistically significant difference between the two materials tested, furthermore there was no difference in SBS between materials bonded to vital or non-vital teeth. After completion of the tests, 20 teeth (10 for each dentin bonding system) were prepared according to standard laboratory procedures for a dentin bond strength test using the Bencor Multi-T system. The values obtained were higher, but again there was no statistically significant difference between the two systems.

Animals↗
PubMed1996

Repairing fractured porcelain: how surface preparation affects shear force resistance.

This article reports on a study of the shear bond strength of porcelain repaired with any of several currently available dentin bonding systems and composite resin. The authors describe the benefits of the use of silane and the decrease in shear bond strength values after thermocycling. The results should be helpful to any practitioner confronted with a restoration that is a candidate for intraoral repair of fractured porcelain.

Analysis of Variance↗
PubMed1995

Microleakage of "surface-sealing" materials.

PURPOSE: To test several dental materials for their sealing properties by subjecting restored teeth to thermal cycling. MATERIALS AND METHODS: Ten teeth per group were assigned at random to six experimental and six control groups. In the experimental groups a resin composite was surface-sealed with IRM, glass ionomer, amalgam, dentin bonding agent and resin composite, experimental hybrid cement, or zinc oxide and eugenol. These six surface-seal materials were placed in bulk in the control group. After cavity preparation, restoration, cut back and application of the surface-seal material, the teeth were subjected to thermal cycling, imbedded and sectioned. A score of 0-3 was given to the amount of dye leakage observed. RESULTS: Zinc oxide and eugenol demonstrated the most leakage, whereas the resin composite system TPH had the least. The results of this in vitro study render the recommendation of zinc oxide and eugenol as a surface-seal material questionable.

Analysis of Variance↗
PubMed1995

Pulp reaction to a dentin bonding agent.

PURPOSE: To determine the pulpal biocompatibility of Prisma Universal Bond 2 (PUB-2). MATERIALS AND METHODS: Class V preparations were made in eight subhuman monkeys to approximately 1 mm from the pulp. In Group 1, the enamel was etched, the primer was placed and dried, PUB 2 was painted, and Prisma-Fil inserted. In Goup 2, the cavity floor was covered with visible light-cured Dycal followed by the steps as in group 1. In Group 3, IRM was used as a negative control. In Group 4, MQ55 silicate cement was used as a positive control. The animals were sacrificed at 5, 25, and 60 days and the teeth processed for histological evaluation. RESULTS: After 5 days, a mild reaction of little concern, which had dissipated in the 25- and 6-day groups, was observed. The material compared favorably to the negative control.

Analysis of Variance↗
PubMed1995

Histologic evaluation of osseointegrated implants restored in nonaxial functional occlusion with preangled abutments.

Of concern with the use of preangled abutments on implants is the transmission of masticatory forces and the angle at which they occur. Nineteen endosseous implants were placed in two subhuman primates. After 6 months, to allow for osseointegration, the implants were fitted with preangled abutments of various degrees and restored with type IV alloy castings. Straight abutments were used as control. Histologic evaluation revealed that, after 1 year of service, the implants exhibited complete osseointegration. Implants, whether restored with straight or preangled abutments, had no adverse effect on the surrounding bone. Soft tissue pockets measured, on average, from 2.2 to 2.6 mm; acute and chronic inflammatory cells were present. When crown loss was observed, it was caused by mechanical failure of components, such as gold screws and the screws used to secure the preangled abutments to the implants. Preangled abutments appear to be a valuable adjunct in implant dentistry, although long-term studies are needed for confirmation.

Animals↗
PubMed1994

Long term clinical evaluation of three luting materials.

A last critical step in the completion of a cast restoration is permanent cementation. With the development of new luting agents the practitioner has to be aware of the physical and biological properties as well as the long term clinical performance of these materials. In this study three commonly used luting agents were evaluated over a four year period. The three cements, a zinc phosphate, a glass ionomer and a resin cement were tested for their reaction to periodontal tissues, pulpal response and other clinical parameters. In twenty six patients, 61 crowns, onlays or bridge abutments were cemented. Evaluations were made at 0 hour, after 7 days, 6 and 12 months and 4 years. In general the cements performed satisfactorily. Health of periodontal tissues adjacent to the crowns improved considerably after 7 days. Postcementation hypersensitivity appeared to be a negligible problem, which was attributed to the time span between preparation and cementation, which exceeded in most instances four weeks. The choice of a final luting agent should be based on anticipated postoperative pulpal reactions, rather than exclusive reliance on physical properties.

Analysis of Variance↗
PubMed1992

Influence of low-viscosity liners on the retention of three luting materials.

A number of materials are available to protect the pulp from postoperative sensitivity. The effect of a calcium hydroxide liner and a dentinal desensitizing agent (potassium oxalate) on crown retention was investigated. Gold crowns were cemented on standardized crown preparations with zinc phosphate cement, glass-ionomer cement, or one of two resin cements. A tensile force was applied until separation occurred. The mean applied force at rupture varied greatly among the groups, indicating that the pulpal protection agent may have a distinct effect on the retention of cast restorations. In addition, other clinical factors, such as angle of convergence, crown height, and total surface area of the tooth should be considered.

Analysis of Variance↗
PubMed1992

Pulp reactions to resin cements.

Several formulas of a resin-filled cement that successfully passed a series of laboratory tests were evaluated for their pulp reactions in primates. Their performance was compared to three controls: a positive control (silicate cement), a negative control (zinc oxide-eugenol) and a control group with the protection of calcium hydroxide. The chemical cure resin cement scored the lowest reactions for the 5-day evaluation. The intermediate and prolonged periods demonstrated no significant differences while average, acceptable responses were recorded. No resin cement formula scored as low as the negative control for the three time periods. Silicate cement, the positive control, scored the greatest inflammatory reaction of any material in the intermediate period, but this response was resolved after 60 days. When the resin cements were used with calcium hydroxide, the traditional reactions to calcium hydroxide were observed; an initial mild irritation that diminished with time and was completely resolved after 60 days. The resin cements, with or without the calcium hydroxide, compared favorably to the negative control IRM after 60 days. If the resin cements are appropriately applied, they are expected to be well tolerated by the human pulp. The microorganisms associated with microleakage (MLM) were minimal and there appeared to be no correlation between the MLM and pulp inflammation.

Analysis of Variance↗