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PubMed2003

Effect of eugenol and non-eugenol containing temporary cement on permanent cement retention and microhardness of cured composite resin.

This present study had three aims: 1) to evaluate the bond strengths of carboxylate and resin cements in cementing cast Co-Cr crowns to pretreatment of composite resin cores with eugenol and non-eugenol containing temporary cements, 2) to determine the microhardness of composite resin treated with temporary cement, 3) to view the surface differences of composite resin with SEM. The composite cores were divided into three experimental groups for the following pretreatments: Group 1, No treatment was provided, Group 2, The external walls of the composite cores were covered with eugenol-containing temporary cement, Group 3, The external walls of the composite cores were covered with non-eugenol containing temporary cement. Analysis of variance results showed that there was a significant difference between all three groups. Temporary cement with eugenol was significantly reduced the bond strength of full crown casting with resin cement compared with non-eugenol. The resin specimens treated with the eugenol-containing temporary cement showed the lowest microhardness values, the non-eugenol-containing temporary cement was not significantly different from those of the control groups.

Analysis of Variance↗
PubMed2005

A randomized controlled study evaluating the effectiveness of a two-step self-etch adhesive with and without selective phosphoric-acid etching of enamel.

OBJECTIVES: The purpose of this randomized controlled clinical trial was to test the hypothesis that a two-step self-etch approach is equally effective to restore cervical class-V lesions as a self-etch approach with beforehand selective etching of enamel using phosphoric acid. METHODS: Twenty-nine patients received two or four restorations randomly following two experimental protocols ('paired-tooth' study design): (1) A 'mild' self-etch adhesive (Clearfil SE, Kuraray) was applied following a self-etch approach on both enamel and dentin (C-SE non-etch); (2) Similar application of Clearfil SE, but including beforehand selective acid-etching of the enamel cavity margins with 40% phosphoric acid (C-SE etch). Clearfil AP-X (Kuraray) was used as restorative composite for all 100 restorations. The clinical effectiveness was recorded in terms of retention, marginal integrity and clinical micro-leakage after 2 years of clinical service. RESULTS: No restoration losses were recorded. Clinical micro-leakage was slight and only rarely observed. No significant differences were found between both groups for the diverse parameters evaluated except for the number of small incisal marginal defects, which was significantly higher in the C-SE non-etch group (McNemar: p = 0.0391). SIGNIFICANCE: The clinical effectiveness of the mild two-step self-etch adhesive Clearfil SE was excellent after 2 years of clinical service. Although in general no difference in clinical performance was recorded when Clearfil SE was applied following either of the experimental protocols, more marginal defects at the enamel side were noticed when enamel was not beforehand etched with phosphoric acid. However, these defects were small and of clinically negligible relevance.

Acid Etching, Dental↗
PubMed1998

Qualitative assessment of stress distribution during insertion of endodontic posts in photoelastic material.

OBJECTIVES: The purpose of this study was to investigate the stress patterns associated with prefabricated endodontic posts during the various stages of insertion according to a number of design characteristics. METHODS: In a photoelastic material with elastic properties comparable to dentin, analyses were performed of the overall stress patterns with polarized light revealing substantial differences in stresses generated by the various posts. The effects of variations in design for certain configurations of the posts were also assessed. RESULTS: One geometric feature was the retentive thread of the post. The stress patterns within the photoelastic material revealed a homogeneous distribution of stress along the entire length of the thread, and more threads induced additional stress. The stress recorded with a vent when the pitch of the thread was 0.8-1.0 mm was classified as minimal-to-mild stress. Another geometric feature considered was the head (coronal extension) of the post. Minimal stress was recorded in the material in contact with the head and the apical end of the post when the contact surface of head was more than 3 mm2. CONCLUSIONS: This study suggests that during insertion of threaded posts the least stress occurs when the head contact surface is sufficient (> or = 3 mm2). A thread with a pitch of 0.8-1.0 mm is most desirable in stress reduction. The number of windings should also be limited (less than six windings) as samples with a substantial number of windings (N = 13 or 30) produce severe stress.

Cementation↗
PubMedDate not supplied

Effect of the diameter on Cu-Al post retention.

This study compared the resistance to removal by traction of abraded cylindrical metal cast posts of Cu-Al (Goldent-LA). The posts had constant length (9 mm) and three different diameters (0.9, 1.3 and 1.7 mm), and were cemented with zinc phosphate cement. The crowns of 36 sound maxillary canines were sectioned, the roots were immersed in resin blocks and the root canals were endodontically treated. The teeth were divided into three groups to be prepared and standardized with the use of a parallelometer with the following burs: Group 1 Largo n. 2; Group 2--Largo n. 4; Group 3--Largo n. 6. The posts were molded with chemically activated resin and after casting they were abraded and their dimensions were confirmed with a digital caliper. After cementation of the posts in the prepared root canals, the samples were kept at 37 degrees C in distilled water for 7 days and subsequently submitted to the traction test in a universal testing machine (Instron 4444). The results showed no statistical difference between the groups. Diameter variation (0.9 mm, 1.3 mm and 1.7 mm) in abraded cylindrical posts cemented with zinc phosphate did not affect resistance to removal.

Analysis of Variance↗
PubMedDate not supplied

Retention of Class 3 composite restorations: retention grooves versus enamel bonding.

This study compared the tensile loads required to dislodge class 3 composite restorations with and without retention grooves. Thirty extracted human maxillary central incisors were divided into two groups of 15 teeth each. A C-shaped class 3 preparation with lingual access was cut into one approximal surface of each incisor to standardized dimensions using a #329 bur. A 0.5-1.0 mm 45 degrees bevel was prepared on the lingual and gingival enamel margins. In one group, an incisal retention point and a gingival retention groove were prepared with a #1/4 round bur to a depth of 0.25-0.5 mm; the other group had no retention grooves/points. A nonretentive 2 mm round "well" with diverging walls was cut 0.5-1.0 mm into the axial dentin to accommodate the head of a pin that was inserted prior to composite restoration. Each pin shaft extended approximally from its incisor. A bonding agent (Universal Bond 3 Primer and Adhesive, L D Caulk) was applied to each preparation, and composite resin (Prisma APH, L D Caulk) was inserted incrementally. Each increment was exposed to 40 seconds of polymerization light. Restoration surfaces were finished and polished with Sof-Lex disks (3M Dental Products). Specimens were thermocycled 6 to 60 degrees C, for 500 cycles, with a 30-second dwell time. They were then positioned in an aligning device, and pins were loaded in tension in an Instron Testing Machine at a head speed of 2 mm/minute to restoration failure. Mean (SD) failure loads in Newtons were: no grooves 83.6 (19.8); grooves 69.6 (18.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Composite Resins↗
PubMed2006

[PVD-layering for increased retention of glass fibre reinforced endodontic posts].

For esthetical and biomechanical reasons root canal posts made of fibre-reinforced composite (FRC) have gained an important role in clinical application. Additionally, in contrast to metal or ceramic posts, FRC-posts offer the option of removal. Prior to adhesive placement of FRC-posts the root canal dentin of the non vital tooth and the post surface have to be preconditioned. Up to now the post preconditioning has to be proceeded in the chair side technique. This leads to an additional time expense in the clinical treatment schedule. Also a certain risk of errors in application during chair side conditioning procedure is of concern. Modern PVD-technologies can help to make the treatment by the manufacturer well in advance of the clinical use more efficient and reliable, as well as saving clinicians valuable chair-time. For this reason the apical surfaces of the posts were intensively cleaned and activated, PVD-layered and coated by a conserving transparent layer. This coating has the meaning to protect the surface against environmental contamination and allows the try-in of the posts without any risk of damage of the preconditioned surface. To prove the stability of the layer system under simulated clinical conditions pull out tests after 180 days'storage in physiological saline solution have been performed.

Cementation↗
PubMed2004

Restoring the interproximal zone using the proximal adaptation technique--part 1.

The concepts of the preadhesive era sanctioned the mechanical removal of healthy, sound tooth structure to perform restorative procedures. This mechanical systematic approach to enhance the retention of the restoration by modifying the cavity form included 6 principles: outline form, resistance form, retention form, convenience form, removal of caries, and finish of the enamel walls, margins, and toilet of the cavity. This philosophy was challenged during the adhesive era with a biologic approach. Dramatic changes in the understanding and control of caries, with a reduction in the incidence and severity of caries, and even the process of detecting decay with chemical agents, has forced clinicians to re-think and modify their preparation designs and principles. Some of the mechanical principles are still being used with current adhesive dentistry and clinicians wonder why they continue to have microleakage, recurrent decay, and sensitivity. The effect of this misdirection could be one of the reasons for the relatively short longevity for some adhesively placed restorations. These adhesive design concepts require the clinician to modify nonadhesive techniques when considering preparation design, restorative material selection, adhesive protocol, and placement procedures and techniques. Although the original design principles are outdated by today's standards they are still applicable in the modern dental practice by simply modifying the 6 basic principles. The clinical objectives in the era of minimally invasive adhesive dentistry has become prevention, preservation, and conservation.

Adhesives↗
PubMed2006

[Retention of fiber posts dependent on different resin cements].

Tooth-coloured adhesive inserted fiber posts are used to restore endodontically treated teeth. In this investigation, the tensile bond strength of two different fiber posts systems (ER DentinPost and DT Light Post) in combination with five different resin cements was tested. The posts were inserted into artificial root canals in bovine dentin using Clearfil Core, RelyX Unicem, Panavia 21ex, Panavia F2.0 und Calibra. Titan posts (ER-Kopfstift), inserted with zincphosphate cement served as control group. ER DentinPost inserted with Clearfil Core had significantly higher tensile bond strengths than in combination with Panavia F2.0 (221.70 +/- 17.99 N) or Calibra (212.37 +/- 45.20 N). DT Light Post in combination with Calibra (338.20 +/- 46.40 N), Panavia F2.0 (321.69 +/- 40.11 N) and Panavia 21ex (290.41 +/- 55.28 N) showed significantly higher tensile bond strengths compared to adhesive cementation with RelyX Unicem (211.57 +/- 32.35 N) and Clearfil Core (131.67 +/- 51.72 N). The tensile bond strength of the control group was in the upper third of the values (315.43 +/- 51.38 N). Optical analysis of the post surface after decementation demonstrated in all cases adhesive-cohesive mixed fractures. The adhesion of resin cement to the fiber posts and resin cement to root canal dentin is influenced by different factors. The combination of fiber post systems with the type of resin cement has a great influence on the tensile bond strength.

Animals↗
PubMed2005

Capacity of coronal dentin to increase fiberglass post retention: a pull-out test.

PURPOSE: To evaluate the capacity of residual dentin in the coronal part of the root canal to increase the retention of serrated fiberglass posts (Extra-glass P-6%). METHODS: 40 freshly-extracted maxillary central incisors were randomly and evenly divided into four test groups (TGs) with no (TG0), one (TG1), two (TG2) and three (TG3) coronal walls, respectively. After shaping, the canals were filled with gutta-percha and prepared to receive fiberglass posts. Coronal wall dentin was etched with 38% phosphoric acid for 60 seconds, rinsed, and dried. Dentin bonding agent (Prime & Bond NT) was applied, and fiberglass posts were luted for 8 mm into the post space using a self-cure composite (ResiLute). All samples were then subjected to tensile forces in a universal testing machine. Data were analyzed with ANOVA and Student t-tests (P< 0.01). RESULTS: The samples with residual coronal dentin showed higher bond strength than the samples without residual crown walls (TG0=100.30N; TG1=201.83N; TG2=263.54N; TG3=278.86N). The differences between the groups were all statistically significant at P< 0.01, except for the difference in tensile strength between TG2 and TG3, which was not statistically significant. Residual crown walls significantly increased the tensile load required to displace the posts.

Analysis of Variance↗
PubMedDate not supplied

Post retention and post/core shear bond strength of four post systems.

As clinicians we continue to search for a post system which will give us maximum retention while maximizing resistance to root fracture. The introduction of several new post systems, with claims of high retentive and resistance to root fracture values, require that independent studies be performed to evaluate these claims. This study tested the tensile and shear dislodgment forces of four post designs that were luted into roots 10 mm apical of the CEJ. The Para Post Plus (P1) is a parallel-sided, passive design; the Para Post XT (P2) is a combination active/passive design; the Flexi-Post (F1) and the Flexi-Flange (F2) are active post designs. All systems tested were stainless steel. This study compared the test results of the four post designs for tensile and shear dislodgment. All mounted samples were loaded in tension until failure occurred. The tensile load was applied parallel to the long axis of the root, while the shear load was applied at 450 to the long axis of the root. The Flexi-Post (F1) was significantly different from the other three in the tensile test, however, the Para Post XT (P2) was significantly different to the other three in the shear test and had a better probability for survival in the Kaplan-Meier survival function test. Based on the results of this study, our recommendation is for the Para Post XT (P2).

Acid Etching, Dental↗
PubMedDate not supplied

Improved retention and bone-tolmplant contact with fluoride-modified titanium implants.

PURPOSE: The purpose of the present study was to investigate whether a fluoride modification of the titanium surface would have an effect on bone response after implantation. MATERIALS AND METHODS: Titanium-oxide-blasted titanium implants with and without fluoride modification were investigated in a rabbit tibia model. Quantitative analysis of surface roughness, biomechanical interlocking, and in vivo tissue reactions in rabbit bone at 1 and 3 months after placement were compared. RESULTS: The fluoride-modified test implants had a slightly smoother surface (Sa: 0.91 +/- 0.14 microm) than the unmodified control implants (Sa: 1.12 +/- 0.24 microm). Significantly higher removal torque values (85 +/- 16 Ncm vs 54 +/- 12 Ncm) and shear strength between bone and implants (23 +/- 9 N/mm2 vs 15 +/- 5 N/mm2) were measured for the fluoride-modified implants after 3 months. The histomorphometric evaluations demonstrated higher bone-to-implant contact for test implants at 1 month (35% +/- 14% vs 26% +/- 8%) and 3 months (39% +/- 11% vs 31% +/- 6%) after placement. DISCUSSION: Implant surface modification with fluoride may result in morphologic and physiochemical phenomena that are of significance for the bone response. Another possible explanation for the findings in the present study is that a surface modification changes the surface chemical structures to be more suitable for bone bonding. CONCLUSION: Based on the biomechanical and histomorphometric data, the fluoride-modified titanium implants demonstrated a firmer bone anchorage than the unmodified titanium implants. These implants achieved greater bone integration than unmodified titanium implants after a shorter healing time.

Animals↗
PubMedDate not supplied

Three-year clinical evaluation of a compomer and a resin composite as Class V filling materials.

The purpose of this study was to evaluate the placement of two restorative materials, including a compomer (F2000, 3M ESPE) and a resin composite (Silux Plus, 3M ESPE), in non-carious cervical lesions using a self-etching bonding agent (F2000 self-etching primer/adhesive) and a fifth generation bonding agent (Single Bond, 3M ESPE) and to evaluate and compare these restorations for marginal discoloration, secondary caries, anatomical form, retention, surface texture and marginal adaptation at baseline and annually for three years. F2000 and Silux Plus were used to restore the teeth with moderate-sized non-carious cervical lesions. F2000 was placed using two different bonding agents: F2000 self-etching primer/adhesive (F2000SE group) and Single Bond (F2000SB group); Silux Plus was placed as a control using Single Bond (SiluxSB group). Thirty restorations of each material/dentin adhesive combination were placed. All restorations were evaluated at baseline and annually for three years using a modified USPHS scale. At the end of the three-year recall, Silux Plus had significantly better surface texture than F2000 (p < 0.0001). In addition, marginal adaptation significantly worsened over time starting at one year, as compared with baseline, for all groups (p < 0.0001). When anatomic form was compared between F2000 and Silux Plus, the p-value was 0.085, demonstrating that F2000 was slightly better than Silux Plus. Likewise, when comparing marginal adaptation between the F2000SE and SiluxSB groups, the p-value was 0.064, demonstrating that F2000 with the self-etching primer had better margins than Silux Plus with Single Bond. No other differences were found among the groups.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2004

A prospective ten-year clinical trial of porcelain veneers.

PURPOSE: The aim of this in vivo study was to evaluate the clinical performance of porcelain veneers after 5 and 10 years of clinical service. MATERIALS AND METHODS: A single operator placed porcelain laminates on 87 maxillary anterior teeth in 25 patients. All restorations were recalled at 5 years and 93% of the restorations at 10 years. Clinical performance was assessed in terms of esthetics, marginal integrity, retention, clinical microleakage, caries recurrence, fracture, vitality, and patient satisfaction. Failures were recorded either as "clinically unacceptable but repairable" or as "clinically unacceptable with replacement needed". RESULTS: Porcelain veneers maintained their esthetic appearance after 10 years of clinical service. None of the veneers were lost. The percentage of restorations that remained "clinically acceptable" (without need for intervention) significantly decreased from an average of 92% (95 CI: 90% to 94%) at 5 years to 64% (95 CI: 51% to 77%) at 10 years. Fractures of porcelain (11%) and large marginal defects (20%) were the main reason for failure. Marginal defects were especially noticed at locations where the veneer ended in an existing composite filling. At such vulnerable locations, severe marginal discoloration (19%) and caries recurrence (10%) were frequently observed. Most of the restorations that present one or more "clinically unacceptable" problems (28%) were repairable. Only 4% of the restorations needed to be replaced at the 10-year recall. CONCLUSION: It was concluded that labial porcelain veneers represent a reliable, effective procedure for conservative treatment of unesthetic anterior teeth. Occlusion, preparation design, presence of composite fillings, and the adhesive used to bond veneers to tooth substrate are covariables that contribute to the clinical outcome of these restorations in the long-term.

Adult↗
PubMed2000

Implant-abutment interface: biomechanical study of flat top versus conical.

BACKGROUND: Overloading has been identified as a primary factor behind dental implant failure. The peak bone stresses normally appear in the marginal bone. The anchorage strength is maximized if the implant is given a design that minimizes the peak bone stress caused by a standardized load. Clinical studies have shown that it is possible to obtain a marginal bone level close to the crest of the implant. Different implant systems make use of different designs of the implant-abutment interface. Different implant-abutment interfaces imply that the functional load is distributed in different ways upon the implant. According to Saint-Venant's principle, this will result in different stress patterns in the marginal bone when this reaches levels close to the implant crest. PURPOSE: One aim of the study was to theoretically investigate if a conical implant-abutment interface gives rise to a changed stress pattern in the marginal bone, as compared to a flat top interface, for an axially loaded mandibular titanium implant, the neck of which is provided with retention elements giving effective interlocking with the bone. Further aims were to investigate if the way in which the axial load is distributed on the flat top and on the inner conus respectively affects the stress pattern in the marginal bone. The pertinent stress was considered to be the bone-implant interfacial shear stress. It was assumed that the marginal bone reached the level of the implant-abutment interface. METHOD: The investigation was performed by means of axisymmetric finite element analysis. RESULTS: The conical implant-abutment interface of the type studied brought about a decrease in the peak bone-implant interfacial shear stress as compared to the flat top interface of the type studied. This peak interfacial shear stress was located at the top marginal bone for the flat top implant-abutment interface whereas it was located more apically in the bone for the conical implant-abutment interface. The way in which the axial load was distributed on the flat top and on the inner conus respectively affected the peak interfacial shear stress level. CONCLUSION: The design of the implant-abutment interface has a profound effect upon the stress state in the marginal bone when this reaches the level of this interface. The implant with the conical interface can theoretically resist a larger axial load than the implant with the flat top interface.

Alveolar Process↗
PubMed2005

Orthodontic bonded retainers.

Retention is usually necessary following orthodontic treatment to overcome the elastic recoil of the periodontal supporting fibres and to allow remodelling of the alveolar bone. The degree of change is variable and largely unpredictable. Bonded lingual retainers have been shown to be an effective means of retaining aligned anterior teeth in the post-treatment position in the long term. Two basic designs of lingual bonded retainers are currently in use. Rigid mandibular canine-to-canine retainers are attached to the canines only. They are effective in maintaining intercanine width but less so in preventing individual tooth rotations. Flexible spiral wire retainers are bonded to each tooth in the segment, their flexibility allowing for physiological movement of the teeth. This design is more effective at preventing rotation of the bonded teeth. Failure of bonded retainers may occur at the wire-composite interface, at the adhesive-enamel interface or as a stress fracture of the wire. Failure of a retainer may lead to unwanted tooth movement. In many cases it will be possible to repair the appliance in the mouth. However, in some instances it will be necessary to replace the retainer. A disadvantage of fixed retainers is that they complicate oral hygiene procedures, and favour the accumulation of plaque and calculus. Despite this, the presence of a bonded retainer appears to cause no increase in incidence of caries or periodontal disease. Use of interdental cleaning aids is required to ensure adequate oral hygiene.

Dental Bonding↗
PubMedDate not supplied

Marginal adaptation, retention and fracture resistance of adhesive composite restorations on devital teeth with and without posts.

This in vitro study generated data on the quality of marginal adaptation, fracture resistance and retention of several indirect adhesive composite configurations on root-treated premolars before and after a long-term fatigue test and compared these results to a control group of adhesive onlays on "vital" teeth. Six root-treated extracted human premolars per group, with four different restorative configurations with and without adhesive fiber posts, were evaluated. Another group of six premolars, "revitalized" by using diluted horse serum to simulate pulpal fluid and restored with adhesive composite onlays, served as the control. Marginal adaptation before and after long-term occlusal loading (1,200,000 occlusal loading cycles at max 49 N) was assessed by using the replica technique and quantitative evaluation in SEM at 200x magnification. The number of lost restorations was recorded after loading. Fracture resistance and fracture patterns were evaluated by using a universal-testing machine on the fatigued samples. No significant differences (p > 0.05) between groups were detected before and after loading for the percentage of "continuous margin" at the total marginal length. Loading had a significant (p < 0.05) effect on the percentage of "continuous margin" for the total marginal length of two groups only. No significant difference (p > 0.05) for fracture resistance was detected and no lost restorations were observed. The results suggest that for both the less decayed and the more significantly decayed devital teeth, the minimally invasive adhesive restorative approach is promising.

Analysis of Variance↗
PubMed2006

In vitro evaluation of the retention of zirconia-based ceramic posts luted with glass ionomer and resin cements.

The retention of zirconia-based ceramic posts (CosmoPost system) luted with glass ionomer and resin cements was evaluated. Thirty-two extracted, caries-free, unrestored teeth were selected and stored in chlorhexidine and water solution. The teeth were endodontically treated and randomly assigned to two groups (n=16). Each tooth was decoronated and prepared to a depth of 10.0 mm from root surface to receive a 1.4 mm diameter zirconium dioxide post. Each group had posts cemented with either glass ionomer cement (Fuji I) or resin cement (Variolink II). The post/teeth specimens were embedded in resin blocks and subjected to tensile testing. The tensile force required to dislodge the cemented posts in a tensile testing machine was recorded. The mean stress values of both groups were analyzed for statistical differences using ANOVA and Student's t-test. Significance level was set at 5%. Mean peak forces at failure (N) and standard deviation for the tested cements were the following: Fuji I = 121.8 (+/-17.4) and Variolink II = 228.1 (+/-36.8). Posts luted with the resin cement presented statistically significant higher tensile bond strength than those retained with glass ionomer (p<0.05). It may be concluded that zirconia posts cemented with resin-based cement (Variolink II) failed at statistically significant higher values compared to those cemented with glass ionomer cement (Fuji I). Regardless of the cement type, the posts failed adhesively at the cement/post interface when subjected to a tensile force.

Acid Etching, Dental↗
PubMed2001

Fracture strength of different core build-up designs.

PURPOSE: To investigate the resistance to fracture of three crown and core combinations, made with different core build-up systems on human teeth, using a standardized test method. MATERIALS AND METHODS: The anatomic crowns were removed from six groups (n = 8) of endodontically treated, human premolars in conformity with a brass master dye, using the Celay duplicating device. Three of these groups were provided with a core build-up with-out an endodontic post (Ti-Core, Photo-Core and Ketac-Molar); two other groups were provided with a core build-up with an endodontic post (a cast post and core, and a composite with a silica post), and one group was not provided with a core. All groups were then prepared in conformity with a master dye. This preparation ended in axial dentin, 2 mm apical from the core build-up. Thus in the sixth group (premolars without a core build-up), this preparation only affected the 2 mm axial dentin (ferrule), which resulted in a small retention area (2 mm axial dentine) for the crown. Finally, a standard crown was cemented and 24 hrs afterwards loaded until fracture in an Instron testing machine at an angle of 45 degrees. For comparison with the standardized procedures, a seventh group (Photo-core without post) was prepared manually, with dimensions similar to the standardized groups. RESULTS: Within the standardized test set-up no significant difference in strength between the 6 groups could be demonstrated. Only in the case of the hand-made Photo-Core and the cast core was the fracture load significantly different (P= 0.01). In addition, this hand-made group displayed a larger standard deviation than the standardized groups. Taking into consideration the fact that the maximum bite force in the bicuspid region is about 580 N, these tests showed that within the limitations of the standardized test set-up, where the samples had no history of fatiguing, a core build-up without a post is an alternative for the conventional cast core. In this study, the fabrication of the standardized samples proved to be accurate, fast and economical. This method also enables the evaluation of the performance of core and crown design combinations in relationship to the amount of remaining tooth structure by using different master dies and, moreover, to reduce the high standard deviation in this kind of research.

Analysis of Variance↗