Polycarbonate Crown Research Articles

Case Series on Personalized Pediatric Posterior Zirconia Crowns

Pediatric dentists must comprehend children's aesthetic perception because kids are increasingly aware of their own and other children's appearance. Many aesthetic restorations are available on the market, including open-faced stainless-steel crowns, pre-veneered stainless-steel crowns, strip crowns, and polycarbonate crowns, but each has its own drawbacks. Prefabricated zirconia crowns are a new trend among pediatric dentists for restoring carious, damaged, and malformed primary molars and anteriors. Customized zirconia crowns, on the other hand, may be able to overcome the limitations of prefabricated crowns in certain situations, particularly molars, resulting in excellent aesthetics and longevity. Our case series illustrates the use and performance of personalized zirconia crowns in a variety of challenging clinical circumstances.

Aesthetic Restoration of Traumatized Deciduous Anterior Teeth Using Custom Fabricated Zirconia Crowns - A Case Report

Loss of anterior teeth in children can adversely affect the aesthetics, decrease masticatory efficiency, cause speech disturbance and result in the development of parafunctional habits and psychological problems. There are various complete crown coverage restorations like polycarbonate crowns, stainless steel crowns (SSC), open-faced SSC, commercially veneered SSC, Figaro crowns and Zirconia crowns. The superior aesthetics, inertness, and biocompatibility of ceramics have made them acceptable as a dental restorative material by clinicians. Zirconia ceramics have become a frequently employed biomaterial in dentistry due to their enhanced aesthetics and mechanical properties.
 The aesthetic management of decayed and traumatized deciduous anterior teeth using complete coverage restoration in children is strenuous owing to their limited size, proximity to the pulp, decreased surface area for bonding, teeth isolation difficulties and lack of cooperation. Structural loss of anterior teeth affects aesthetics, impairs mastication and phonetics, causes eruption disturbance of permanent teeth and leads to the development of non-nutritive habits. This may result in a psychosocial crisis in the patient including reduced self-esteem.
 Full coronal restorations like polycarbonate crowns, strip crowns, and modifications of stainless-steel crowns including the open-faced and pre-veneered crowns are being used by clinicians to restore discoloured incisors. However, they are often associated with technical, functional, or aesthetic limitations. Over the past decades, advancement in different technologies in the sphere of dentistry and the immense booming of dental materials have always resulted in a continuous re-assessment of different treatment principles so employed. Paediatric zirconia crowns were introduced in 2010 and have gained popularity for aesthetic considerations.[1] Zirconia crowns are clinically justifiable and with greater parental gratification when compared with other full coverage coronal restorations. Zirconia crowns express high strength, aesthetics, durability, biocompatibility, reduced wear of opposing teeth, and cause less gingival irritation.

Gamut of tooth coloured opportunities to reinstate the paediatric smile: A review

Early Childhood Caries has been acknowledged as a root of severe decay in children at a global level. Most frequently we see involvement of upper incisors followed by the molars. This disturbs the phonetics and most importantly the aesthetics of the child. Over the years, there have been plenteous studies concerning the restoration of primary teeth. As the technology advanced, the level of parental satisfaction with the conventional stainless-steel crowns lowered, this made the Paediatric dentists to search for an aesthetic restoration for the decayed primary tooth. Treatment of decayed anterior teeth can be done by a variety of techniques which includes Strip crowns, Polycarbonate crowns, Cheng crowns, acrylic crowns, Zirconia crowns and the most recent is Figaro crowns. The advent of such advanced techniques and materials helps in creating beautiful restorations which help children to improve their self-image as the child aesthetics is the guide to the adult aesthetics. This article gives an overview of few of the aesthetic options for rehabilitation of ECC cases.

Release of Bisphenol A from Milled and 3D-Printed Dental Polycarbonate Materials

Polycarbonates are polymers of bisphenol A (BPA), a well-known endocrine disruptor. This study evaluated the release of BPA from polycarbonate crowns that were (1) milled from Temp Premium Flexible (ZPF, Zirkonzahn, Italy) or Tizian Blank Polycarbonate (TBP, Schütz Dental, Germany), or (2) 3D-printed (Makrolon 2805, Covestro, Germany). Commercial prefabricated polycarbonate crowns (3M, USA) and milled poly(methyl methacrylate) (PMMA) crowns (Temp Basic, Zirkonzahn, Italy) were included for comparison. The crowns were stored at 37 °C in artificial saliva (AS) or methanol, which represented the worst-case scenario of BPA release. Extracts were collected after 1 day, 1 week, 1 month and 3 months. BPA concentrations were measured using liquid chromatography-tandem mass spectrometry. The amounts of released BPA were expressed in micrograms per gram of material (μg/g). After 1 day, the highest amounts of BPA were measured from milled polycarbonates, TBP (methanol: 32.2 ± 3.8 μg/g, AS: 7.1 ± 0.9 μg/g) and ZPF (methanol 22.8 ± 7.7 μg/g, AS: 0.3 ± 0.03 μg/g), followed by 3D-printed crowns (methanol: 11.1 ± 2.3 μg/g, AS: 0.1 ± 0.1 μg/g) and prefabricated crowns (methanol: 8.0 ± 1.6 μg/g, AS: 0.07 ± 0.02 μg/g). Between 1 week and 3 months, the average daily release of BPA in methanol and AS decreased below 2 μg/g and 0.6 μg/g, respectively. No BPA was released from PMMA in AS, and the cumulative amount released in methanol was 0.2 ± 0.06 μg/g. In conclusion, polycarbonates could be a relevant source of BPA, but the current tolerable daily intake of BPA (4 μg/kg body weight) should not be exceeded.

Comparison of Fracture Strengths among different Commonly Placed Anterior Esthetic Restorations for Primary Dentition: An in vitro study.

Four groups of esthetic restoration for primary anterior teeth were tested for fracture strength: 1) Fifteen all-ceramic zirconia-based crowns cemented with glass ionomer cement, 2) Fifteen all-ceramic zirconia-based crowns bonded with a self-adhesive resin cement, 3) Fifteen polycarbonate crowns cemented with a polymer reinforced zinc-oxide eugenol and 4) Fifteen resin strip crowns. All restorations were placed and cemented on reproductions of dies in an independent laboratory at Delhi, India. All samples underwent loading until fracture or dislodgement with the Universal Testing Machine. The force in Newton (N) required to produce failure was recorded for each sample and the type of failures was also noted and characterized. One-way analysis of variance (ANOVA) test and the Tukey and Scheffe's post hoc comparisons were used for statistical analyses. In this invitro study, results were measured in Newtons (N). Group 1 (410.9±79.5 N) and Group 2 (420.5±57.8 N) had higher fracture strength than Group 3 (330.3±85.6 N) and Group 4 (268.4±28.2 N). These differences were statistically significant at P≤.05 among the sample groups. No significant difference was found between groups 1 and 2 (P = 0.984) nor between groups 3 and 4 (P =0.104). Among type of failures, majority of restoration fractures for zirconia-based crowns and resin strip crowns were due to cohesive failures and polycarbonate crowns had predominantly mixed failures. Under the limitations of this in vitro study, it could be concluded that all-ceramic zirconia-based crowns attained the highest fracture strength among all restorative samples tested regardless of the type of luting agent employed (P<.01). Cohesive failures were commonly observed in the zirconia crowns and resin strip crowns, whereas polycarbonate crowns revealed predominately mixed failures.

Esthetic restoration of anterior teeth using temporization material in deciduous dentition: A case report

Dental caries is a major health problem in pre school, primary school going children and adolesecents. However, every individual is susceptible to this ailment during the course of its life. A number of treatment modalities are available for restoring primary incisors which include pre-veneered stainless steel crowns, polycarbonate crowns, resin strip crowns and zirconia crowns. This case report demonstrates a clinical technique for restoring primary incisors using a new temporization material. Keywords: Dental caries, Crowns, Temporization material, Primary incisors.

Anterior and posterior crowns in primary dentition: A contemporary review

One of the most common problems faced by clinicians in pediatric dentistry is to provide restorations in primary and young permanent teeth which are aesthetically acceptable, durable and cost effective. A wide range of crowns are available for this purpose and the selection of the most appropriate crown will help achieve better final outcomes of treatment. The vary widely from being the directly bondable to the tooth surface to crowns which are luted onto the tooth surface. They may also vary in composition from metal crowns with or without facings to resin, polycarbonate, and ceramic crowns. This review attempts to assimilate and bring out the varied array of pediatric crowns available in the published data for utilization by the pedodontist as per the needs of the patient. The knowledge of the available resources and the various advantages, disadvantages and properties of the same will go a long way in enhancing the clinician’s ability to make the most appropriate choice for the patient.

Effect of different surface treatment methods on the shear bond strength of orthodontic brackets to temporary crowns

The number of adult patients seeking orthodontic treatment has been consistently increasing. Since the placing of the final restoration must be postponed until the completion of the orthodontic treatment, provisional restoration is recommended for the duration of the orthodontic treatment. These surfaces have special chemical properties, which necessitate the orthodontists to prepare the bonding area with special measures. Polycarbonate and polymethylmethacrylate (PMMA) crowns (n=80) were randomly subdivided into 4 groups. Conditioning methods were grinding, sandblasting, CO2 laser and methyl methacrylate application. Samples underwent SBS testing. A scanning electron microscope (SEM) analysis was carried out. The data was analysed with ANOVA, Student t-test and Post-hoc test. Adhesive remnant index (ARI) was analysed with Chi2 test. In all surface treatments, the mean Shear Bond Strength (SBS) of PMMA was significantly higher than that of polycarbonate (P<0.001). In the polycarbonate groups, there was a significant difference between the mean SBS of the four treatment methods (P<0.001). However, there were no significant differences in PMMA group (P=0.076). In both crown materials, the mode of the failure was adhesive type, regardless of the conditioning method (P>0.05). PMMAs rendered higher bond strength than polycarbonates. In PMMA, all the surface treatment methods resulted in acceptable bond strength. However, if bonding the brackets to polycarbonate crown is needed, other conditioning methods are preferred over CO2 laser.

Clinical management of a complicated crown-root fracture of maxillary central incisor in a 12-year-old patient

Traumatic injuries to permanent maxillary anterior teeth are seen commonly in children. Esthetic and functional rehabilitation of these teeth is important. A 12-year-old male patient reported to the Department of Paedodontics and Preventive Dentistry with fracture of the permanent maxillary right central incisor. Clinical and radiographic examinations revealed the presence of a complicated crown-root fracture. This case report describes the management of complicated crown-root fracture by endodontic therapy, orthodontic extrusion, fiber post placement, core build-up with composite, and esthetic restoration using polycarbonate crown.

Esthetic zirconia crown in pedodontics

There are different types of restorations for complete crown coverage. These restoration techniques include polycarbonate crowns, acid etched crown, stainless steel crown (SSC), open–faced SSC with veneer placed on chair side and commercially veneered SSC. Each of these techniques presents technical, functional or esthetic compromises that complicate their efficient and effective usage. Recently, zirconium dioxide ceramic prefabricated crown has been used in the treatment of primary teeth. The choice of full coverage restoration for primary teeth must provide an esthetic appearance in addition to restoring function and durability. This article presents an overview of zirconia crowns in pedodontics and a case study of full coronal restoration using zirconia crown.

Effect of nightguard vital bleaching gel on the color stability of provisional restorative materials.

To assess the hypothesis that there was no difference in effect of 10% and 15% tooth bleaching agents on color stability of materials used for provisional fixed dental prosthesis. Fifteen samples from two materials used for provisional fixed dental prosthesis: methacrylate-based and composite-based materials and 15 preformed polycarbonate crowns soaked in bleaching gel or distilled water. Spectrophotometer recorded color of specimens at baseline, after 3, 7, and 14 days. Data were statistically analyzed using two-factor ANOVA test to compare the color stability of tested materials. Methyl-based provisional material exhibited statistically higher color change when exposed to 10% and 15% bleaching gel (delta EFNx01: 9.0 and 11.1, respectively) as compared to distilled water (delta EFNx01: 2.9). Delta EFNx01 of composite-based material specimens exposed to distilled water was statistically higher (6.3) than specimens exposed to 10% and 15% bleaching gel (1.5 and 1.1, respectively). Polycarbonate crowns showed a statistically lower color change when exposed to 15% (0.9) than to 10% bleaching gel (5.1) or distilled water (5.5). Composite-based provisional material showed highest color stability when exposed to vital tooth bleaching gel, whereas methacrylate-based material was the least color stable. Polycarbonate crowns were more color stable when exposed to 15% bleaching gel as opposed to 10% bleaching gel.

Arresting rampant dental caries with silver diamine fluoride in a young teenager suffering from chronic oral graft versus host disease post-bone marrow transplantation: a case report

BackgroundRampant caries is an advanced and severe dental disease that affects multiple teeth. This case describes the management of rampant caries in a young teenager suffering from chronic oral graft versus host disease after allogeneic bone marrow transplantation.Case presentationA 14-year-old Chinese boy suffering from β–thalassemia major was referred to the dental clinic for the management of rampant dental caries. An oral examination revealed pale conjunctiva, bruising of lips, and depapillation of tongue indicating an underlying condition of anemia. The poor oral condition due to topical and systemic immunosuppressants was seriously aggravated, and rampant caries developed rapidly, affecting all newly erupted, permanent teeth. The teeth were hypersensitive and halitosis was apparent. Strategies for oral health education and diet modification were given to the patient. Xylitol chewing gum was used to stimulate saliva flow to promote remineralization of teeth. Silver diamine fluoride was topically applied to arrest rampant caries and to relieve pain from hypersensitivity. Carious teeth with pulpal involvement were endodontically treated. Stainless steel crowns were provided on molars to restore chewing function, and polycarbonate crowns were placed on premolars, upper canines and incisors.ConclusionThis case report demonstrates success in treating a young teenager with severe rampant dental decay by contemporary caries control and preventive strategy.

Dental Implants: Early Versus Standard Two-Stage Loading (Animal Study)

Direct bone formation on the implant surface is a treatment goal in implant dentistry. It was always thought that a healing period of 3 months for the lower jaw and 5-6 months for the upper jaw was required for osseointegration to occur. Recent studies, however, show that with the early loading protocol, osseointegration is possible as well. The goal of this study was to evaluate clinical, histologic, and histomorphometric parameters of implants with early loading protocols and implants that did not undergo the early loading protocol. In this experimental study, the first to the fourth premolar teeth were extracted from the lower jaws of 3 dogs. After a healing period of 3 months, 12 BioHorizons internal implants 4.5 × 10.5 mm were placed in the mandible of the dogs. The implant stability quotient (ISQ) was recorded. After 3 weeks, half of the implants were exposed, and after recording ISQ, polycarbonate crowns were placed on them and occlusion was adjusted so that there was no contact in centric occlusion and no lateral movement with the opposing teeth. After 3 months, the ISQs were recorded for all the implants. Bleeding upon probing and pocket depths were measured for the early loading implants. All the implants were removed using a trephine bur, and cross-sections of 150 μm were prepared, from which the bone implant contact (BIC) and the type of bone around them were obtained. Statistical analysis was conducted with independent t test, paired t test, and repeated analysis of variance. The BIC for the early loaded group was 46.17% ± 12.89%, and for the unloaded group was 44.4% ± 10.45%. This difference was not statistically significant (P = .811). The ISQ for the implants in the early loaded group (before they were removed) was 71 ± 7.35 and that of the unloaded group was 66.75 ± 11.86 .These differences were statistically insignificant. With regard to the result of this study, and the fact that the 2 groups showed no statistically significant differences in a number of major aspects, such as BIC and ISQ, it seems possible to load implants with an earlier than usual protocol with no adverse effects on implant success. It is necessary, however, to follow certain protocols for this type of loading.

Effects of surface conditioning on the shear bond strength of orthodontic brackets bonded to temporary polycarbonate crowns

An increase in the number of adults seeking orthodontic treatment has given rise to new problems for orthodontists, one of which is the need to bond orthodontic brackets to teeth restored with temporary crowns. Many prefabricated temporary crowns are composed of polycarbonates or thermoplastic polymers; bonding to these surfaces is complex because of the composition, surface integrity, and resistance of the crowns. The bond must be sufficient to resist breakage from the forces of orthodontic biomechanics and oral functions including mastication. The purpose of this study was to test, in vitro, the effect of different surface treatments on the shear bond strength of metal and ceramic orthodontic brackets bonded to temporary polycarbonate crowns. Eighty polycarbonate crowns for the maxillary right central incisor were evenly divided into 4 groups, and the facial surfaces were subjected to one of the following conditions: group A (control): no treatment; group B: the surface was sandblasted with 50 mum aluminum oxide particles; group C: the glazed surface was removed with a diamond bur; and group D: the surface was etched with 9.6% hydrofluoric acid. Precoated Victory metal brackets (3M Unitek, Monrovia, Calif) were bonded to the facial surface of half (n = 10) of the polycarbonate crowns in each group, and precoated Clarity ceramic brackets (3M Unitek) were bonded to the facial surface of the other half (n = 10). Each was debonded with a shear load in a universal testing machine at a crosshead speed of 0.254 mm per minute, and the adhesive remnant index (ARI) was used to analyze the sites of bond failure. Analysis of variance (ANOVA), post-hoc t test with the Bonferroni adjustment, Student t test, and chi-square test with the Yates correction were used for statistical analysis. There was a significant difference between group B (sandblasting) and all other ceramic and metal groups. In the metal groups, there was a slight difference between group C (diamond bur) and group A (control). According to the ARI, sandblasting was the only surface treatment to significantly affect the adhesion of metal and ceramic brackets to polycarbonate crowns. There was no statistically significant difference between the metal and ceramic brackets in group B (sandblasting). There was a statistically significant difference between metal and ceramic brackets in each group, with the exception of group C (diamond bur), which was just below statistical significance. Metal and ceramic orthodontic brackets bonded to temporary polycarbonate crowns will most likely not withstand the forces of orthodontic biomechanics. However, sandblasting polycarbonate crowns consistently increased the shear bond strength of metal and ceramic brackets. A diamond bur effectively roughens the surface of a polycarbonate crown but with no gain in bond strength. Likewise, etching the surface of polycarbonate crowns with 9.6% hydrofluoric acid is ineffective. Ceramic brackets bonded to sandblasted polycarbonate crowns produced the highest mean shear bond strength (2.87 MPa), although this value is far below bond strengths with natural tooth surfaces.

Bondsteel Fixed Partial Denture: A Provisional Indirect Technique for In-the-Field Dental Emergencies

This article presents a modified resin-bonded fixed partial denture technique of replacing a single missing anterior tooth under limitation of material and time. This technique involved a small section of an oral surgery arch bar that was bent and fitted passively into the grooves that were prepared in the lingual of the abutment teeth. A polycarbonate crown was fitted passively on the arch bar by a thin layer of Vaseline. The polycarbonate crown was then filled with acrylic resin to bond the polycarbonate crown and the arch bar together. The result provides an esthetic appearance and a 4-month clinical success without complication. Thus, this technique is a short-term solution for clinics that have limited resources for a definitive treatment.

Evaluation of different sterilization and disinfection methods on commercially made preformed crowns

The aim of this study was to evaluate the changes caused by different sterilization or disinfection methods on the vestibular surface of four commercially made preformed crowns using stereomicroscopy and scanning electron microscopy (SEM). Preformed crowns (NuSmile Primary Anterior Crown (NSC), Kinder Krowns (KK), Pedo Pearls (PP) and polycarbonate crowns (PC)) were sterilized and/or disinfected by one of the following techniques: no sterilization or disinfection (G1 control group); steam autoclaving at 134 degrees C (30 psi) for 4 min (G2); steam autoclaving at 134 degrees C (30 psi) for 12 min (G3); steam autoclaving at 121 degrees C (15 psi) for 30 min (G4); and ultrasonication in a bath containing 4% Lysetol AF for 5 min at room temperature (chemical disinfection) (G5). Scanning electron micrographs of the crowns were taken before and after their sterilization or disinfection. The changes on the vestibular surface were then scored for the presence or absence of crazing, contour alteration, fracturing, and vestibular surface changes. The data were analyzed statistically using the chi-square test. No changes were observed before and after sterilization or disinfection in the stereomicroscopic evaluation of the vestibular surface of the crowns. However, all methods in which steam autoclaving was used to sterilize the crowns caused significant (P < 0.05) crazing and contour alterations of the vestibular surface of the crowns when they were examined by SEM. Chemical disinfection using an aldehyde-free disinfectant is the preferred method of disinfection for crowns that have been used previously in other dental patients.

A Comparison of Two Different Methods and Materials Used to Repair Polycarbonate Crowns

The aim of this study was to evaluate the bond strength and crown-repair material interface of polycarbonate crown repaired using flowable resin composite and hybrid resin composite following two different surface preparations. The facial surfaces of fifty-two polycarbonate crowns were flattened and roughened. Specimens were then divided into four test groups. A bonding agent alone (Groups 1 and 2) or a combination of methylmethacrylate (MMA) + bonding agent (Groups 3 and 4) was applied to the prepared surfaces. Then either a flowable (Groups 1 and 3) or a microfilled hybrid (Groups 2 and 4) resin composite was placed on the surfaces. Forty-eight of the original fifty-two specimens were used for shear bond strength testing. Failure types (adhesive, cohesive, and mixed) were evaluated. The remaining four specimens, one from each group, were used for crown-resin composite interface analysis using a scanning electron microscope (SEM). There were significant differences in both mean shear bond strength values and failure types (P<0.05). The SEM evaluation revealed a close interface relationship in Groups 3 and 4. MMA monomer application on a polycarbonate crown prior to application of an adhesive agent improved the shear bond strength of the repair material.

Fracture Resistance of Various Temporary Crown Materials

The aim of this study was to evaluate the fracture resistance of various provisional crown materials using an in vitro model test system. In the present study polycarbonate crowns, prefabricated by the manufacturer (3M Polycarbonate Crown), and the temporary crowns, fabricated in the dental laboratory environment, were fabricated using bis-acryl composite (Protemp II), autopolymerizing PMMA resin (BISICO Temp S), and heat-polymerized PMMA resin (Major C&B-V Dentine). All temporary crowns were stored in distilled water for 24 hours at room temperature prior to testing. The crowns were seated on metal dies, fabricated from Cr-Co alloy (AZ Dental, Konstanz, Germany), and then tested using the indenter of a Hounsfield testing machine (Hounsfield Tensometer, Hounsfield Test Equipment, Raydon, England). The tip of the indenter was located at a position one-third of the way down the inciso-palatine surface at 135 masculine. The data were statistically analyzed for differences using one-way analysis of variance (ANOVA) and the Tukey HSD test (P < .05). Additionally, the types of failure obtained from the fracture load test were examined using 10x magnification with a stereo microscope. The results of the present study indicated polycarbonate crowns were significantly different from the BISICO Temp S, Protemp II, and Major C&B-V Dentine (P < .05) groups. This in vitro study shows polycarbonate crowns may be preferable to the other types of temporary crowns used in this study.

Bisphenol A from dental polycarbonate crown upregulates the expression of hTERT.

Bisphenol A (BPA) is one of the endocrine-disrupting chemicals (EDCs) that possess estrogen-like biologic activity. Many dental materials have been reported to release BPA. However, there are few reports available on the release of BPA from dental polycarbonates. The purpose of this study was to investigate the release of BPA from dental polycarbonate crowns and to evaluate the estrogenic activity of BPA. Polycarbonate crowns were immersed in five solvents (water, ethanol, n-hepthane, acetic acid, and acetonitrile) at 37 or 65 degrees C for 24 h. The elution from the material was analyzed by high-performance liquid-chromatography (HPLC) and mass-spectrometry (MS) analysis. BPA release was detected corresponding to the degradation of dental polycarbonates under the some storage conditions (ethanol, acetic acid, and acetonitrile). A previous report proved that estrogen increased human telomerase catalytic subunit (hTERT) mRNA, whereas the effect of EDCs on the hTERT promoter has never been reported. The estrogenic activity of BPA was analyzed by luciferase assay with the use of the hTERT promoter. This assay revealed that BPA was a positive regulator of hTERT transcription. In addition, quantitative real-time PCR analysis showed that BPA increased the expression level of hTERT mRNA in MCF7 cells. Herein, it is demonstrated that hTERT is a new target of BPA.

Effect of water temperature on the fit of provisional crown margins during polymerization

Statement Of Problem. When fabricating a provisional crown with the direct technique, dentists are concerned with margin discrepancies that result from polymerization shrinkage. Purpose. This in vitro study examined the effect of water temperature on the fit of provisional crown margins during resin polymerization. Material And Methods. The experiment was designed to simulate a direct technique to fabricate provisional crowns. After mixing autopolymerizing methyl methacrylate resin, the material was placed in a preformed polycarbonate crown. The crown was seated on a prepared premolar-shaped die with a shoulder margin. After 1 minute and 50 seconds, the crown was removed and polymerization was continued under the following conditions: 20°C air, and water at 0°C, 10°C, 20°C, 30°C, 40°C, 60°C, and 80°C. Six minutes after polymerization, the crown was trimmed and reseated on the die. Discrepancy of crown margin was measured with a 3-dimensional digitizer. Results. Margin discrepancy varied with the condition during resin-polymerization (ANOVA, P <.001). The crowns polymerized in 20°C and 30°C water revealed the best margin fit, showing 3 times more accurate margin fit than those polymerized in 20°C air (Bonferroni/Dunn procedure, P <.01). Conclusion. Conditions during resin polymerization were significant factors that affected margin fit of provisional crowns using the direct technique. Water temperatures of 20°C and 30°C produced the best fit at the margin of the provisional crown. (J Prosthet Dent 1999;82:658-61.)