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At least 811 records · Page 45Linked to original sources
PubMed1997

The effect of environmental pressure changes during diving on the retentive strength of different luting agents for full cast crowns.

STATEMENT OF PROBLEM: The effect of pressure cycling on the bond strength of cement luting agents is largely unknown. PURPOSE: This study investigated the effect of pressure cycling on the retention of full cast crowns to extracted teeth. MATERIAL AND METHODS: Sixty extracted single-rooted premolar teeth had full cast crowns cemented, 20 with a zinc phosphate cement, 20 with a glass ionomer, and 20 with a resin cement. After 7 days of storage, each of the teeth in the experimental groups was pressure cycled 15 times from 0 to 3 atmospheres (304 KPa), after which the force required to dislodge the crowns was tested in an Instron testing machine. RESULTS: A significant difference was found (Students t test; p > 0.01) between the force required to remove the crowns in the zinc phosphate control (142.10 +/- 36.42 N) and experimental (15.93 +/- 11.13 N) groups and the glass ionomer cemented control (186.33 +/- 24.33 N) and experimental (91.50 +/- 33.07 N) groups; no difference was found between the resin cemented control (291.15 +/- 78.48 N) and experimental (281.32 +/- 85.43 N) groups. CONCLUSION: This study showed that the retention of full cast crowns to extracted teeth is reduced after pressure cycling if the crowns are cemented with either zinc phosphate cement or glass ionomer cement. Dentists should consider using a resin cement when cementing crowns and fixed partial dentures for patients, such as divers, who are likely to be exposed to pressure cycling.

Air Pressure↗
PubMed2005

Effects of eugenol and non-eugenol endodontic fillers on short post retention, in primary anterior teeth: an in vitro study.

The aim of this study was to measure in vitro the tensile bond strength of short composite posts in anterior primary teeth filled with calcium hydroxide and eugenol-based endodontic filling materials. Means of tensile strength ranged from 2.66 to 3.56 MPa. Statistical analysis (ANOVA) revealed that there were no statistically significant differences between the groups. It was concluded that the type of filling material used in the endodontic treatment did not interfere with the tensile strength.

Calcium Hydroxide↗
PubMed2003

[Theoretical and clinical prerequisites for the use of fragments of molar roots as abutment for dentures].

Experimental and clinical studies confirmed the possibility of using fragments of a multi-root tooth as abutment tooth for a bridge denture. When planning orthodontic treatment, choosing the abutment teeth, designing the denture, and treating the patient the orthodontist should be able to use the information on the maximum allowable loading of the fragments of resected teeth. A positive factor in utilization of the remaining tooth fragment is the ratio of clinical crown and root length, which should be inversely proportional. The study showed that retention of the morphofunctional integrity of dentition is possible when using dentures ensuring the optimum regulation stress (no higher than physiologically tolerable) in abutment tissues. Analysis of remote clinical and X-ray data showed normalization of the periodontal function of tooth fragments after tooth-sparing operations in cases when the patients were fitted with prostheses with consideration for theoretically valid methods for estimation of reserve force.

Adolescent↗
PubMedDate not supplied

Clinical evaluation of two different methods of stainless steel esthetic crowns.

PURPOSE: The purpose of this study was to compare the clinical success of stainless steel crowns (SSCs) made esthetic by open facing or veneering on posterior primary teeth. METHODS: Thirty-three crowns (18 open-face and 15 veneered) were placed and followed up for 18 months with semiannual evaluations. RESULTS: Crowns made esthetic with the open-face method showed a success of 95%, while the veneered crowns showed a success of 80% based on greater than two thirds facing retention. Statistical evaluation by 2 proportion test showed no significant difference between groups (P>.05). In addition, a statistically significant difference was found between upper and lower crowns by Fisher's exact test (P<.05). CONCLUSIONS: This study showed that open-face SSCs had a higher but not significantly different success rate than veneered SSCs. Upper-arch crowns exhibited a higher success rate than those in the lower arch.

Child↗
PubMed1992

Use of luting agents with an implant system: Part I.

When removal of the provisionally cemented superstructure from a cemented abutment becomes necessary, the retentive strengths of the abutment/fixture and superstructure/abutment luting agents become important considerations. This study compared the retentive strengths of castings cemented to machined titanium implant abutments and to a human premolar with three provisional luting agents. Also tested were the retentive strengths of cast noble metal implant abutments cemented into titanium fixtures with three permanent luting agents both dry and after storage in 0.9% physiologic saline for 30 days at 37 degrees C. No significant differences (alpha < 0.05) were noted in retentive values between the cemented castings on the titanium abutments and the natural tooth. The Temp Bond zinc oxide-eugenol luting agent exhibited a lower mean retentive strength than the IRM reinforced zinc oxide-eugenol and Life calcium hydroxide luting agents. Ketac Cem glass-ionomer cemented abutments that were stored in saline exhibited a significantly higher mean retentive strength than abutments cemented with either Core Paste or Resiment resin luting agents. On the basis of results from this study, it may be concluded that superstructures provisionally cemented with Temp Bond, IRM, or Life luting agents may be removed from implant abutments without disturbing the abutment/fixture or implant bond.

Analysis of Variance↗
PubMed1997

Influence of tooth surface roughness and type of cement on retention of complete cast crowns.

STATEMENT OF PROBLEM: Bond strength of luting cements to dentin is a critical consideration for success of cast restorations. PURPOSE OF STUDY: This study determined the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of respective cemented restorations. MATERIAL AND METHODS: Ninety artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a milling machine on extracted human teeth. Diamond, tungsten carbide finishing, and cross-cut carbide burs of similar shape were used. The crowns in each group were randomly subdivided into three subgroups of 10 for the three luting cements selected for this study: zinc phosphate cement (Fleck's), glass ionomer cement (Ketac-Cem), and adhesive resin cement (Panavia-EX). Retention was evaluated by measuring the tensile load required to dislodge the artificial crowns from tooth preparations with an Instron testing machine. RESULTS: Analysis of forces with parametric analysis of variance and Tukey's Studentized Range (HSD) disclosed a statistically significant difference for both luting cement and finishing burs (p < 0.001). A statistically significant interaction effect (p < 0.001) was also found. The greatest retention value (372.9 N) was for tooth preparations refined with carbide burs and cemented with Panavia-EX cement. However, the least retention value (201.6 N) was for tooth preparations completed with finishing burs and luted with zinc phosphate cement. CONCLUSIONS: Significant differences were found among all three cements for finishing burs. However, there was a difference only between Panavia-EX cement and the other two cements for tungsten carbide burs. For diamond rotary instruments, zinc phosphate cement was significantly different from glass ionomer and Panavia-EX cements.

Analysis of Variance↗
PubMed2003

A conical implant-abutment interface at the level of the marginal bone improves the distribution of stresses in the supporting bone. An axisymmetric finite element analysis.

It has been hypothesized that marginal bone resorption may result from microdamage accumulation in the bone. In light of this, a dental implant should be designed such that the peak stresses arising in the bone are minimized. The load on an implant can be divided into its vertical and horizontal components. In earlier studies, it was found that the peak bone stresses resulting from vertical load components and those resulting from horizontal load components arise at the top of the marginal bone, and that they coincide spatially. These peak stresses added together produce a risk of stress-induced bone resorption. Using axisymmetric finite element analysis it was found that, with a conical implant-abutment interface at the level of the marginal bone, in combination with retention elements at the implant neck, and with suitable values of implant wall thickness and modulus of elasticity, the peak bone stresses resulting from an axial load arose further down in the bone. This meant that they were spatially separated from the peak stresses resulting from horizontal loads. If the same implant-abutment interface was located 2 mm more coronally, these benefits disappeared. This also resulted in substantially increased peak bone stresses.

Bone Resorption↗
PubMed2001

Magnets in prosthetic dentistry.

Magnetic retention is a popular method of attaching removable prostheses to either retained roots or osseointegrated implants. This review chronicles the development of magnets in dentistry and summarizes future research in their use. The literature was researched by using the Science Citation Index and Compendex Web from 1981 to 2000. Articles published before 1981 were hand researched from citations in other publications. Articles that discussed the use of magnets in relation to prosthetic dentistry were selected.

Dental Prosthesis Retention↗
PubMedDate not supplied

Influence of fatigue loading on the performance of adhesive and nonadhesive luting cements for cast post-and-core buildups in maxillary premolars.

PURPOSE: This study evaluated the influence of fatigue loading on the performance of an adhesive and a nonadhesive cement for cast post-and-core restorations in maxillary premolars. MATERIALS AND METHODS: The adhesive cement used was Panavia 21, a resin-based composite cement, and the nonadhesive cement was PhosphaCem/C, a zinc-oxy-phosphate cement. The coronal sections of single-rooted human maxillary premolars were removed at the level of the proximal CEJ. After endodontic treatment, a cast post and core was prepared for each tooth and cemented into the root canal with either Panavia 21 (n = 8) or PhosphaCem/C (n = 8). Half of the specimens from each cement group were exposed to fatigue loading almost perpendicular to the axial axis; the other half were used as controls. Three parallel transverse root sections were cut from each specimen and used for evaluation of the influence of fatigue loading. For each section, cement integrity was studied by SEM, and retention strength of the cemented post section was determined with a push-out test. RESULTS: For SEM evaluation and the push-out test, Panavia 21 proved significantly better than PhosphaCem/C. However, fatigue loading did not show any effect. CONCLUSION: Under the conditions of this study, fatiguing of cemented cast post-and-core restorations was not decisive as a single test to evaluate the quality of the cement.

Adhesives↗
PubMed2000

Influence of previous restoration of the tooth on prognosis of crowns with dowels.

Due to extensive loss of tooth substance the restoration of endodontically treated tooth requires intracanal dowels to give an efficient strength for the crown. The aim of our study was to investigate whether the previous type of restoration of the tooth, i.e. composite restoration with screw post versus one-piece dowel crown, has an effect on the prognosis of crowns with dowels. The material consisted of 111 single crowns and as a previous restoration there were 83 composite restorations with screw posts and 28 one-piece dowel crowns. The mean follow-up time was 78 months (range 6--163 months). The cumulative survival was 87% for one-piece dowel crowns and 84% for composite resins with screw posts. There were six root fractures, four losses of cement retention and one tooth extraction due to caries in crowns with previous composite resin with screw posts. In one-piece dowel crowns as a previous restoration there were two root fractures and one tooth extraction for periodontal reasons. In conclusion, it seems that the previous restoration has no marked effect on the prognosis of crowns with dowels when studying a composite resin restoration with screw post and a one-piece dowel crown.

Adult↗
PubMedDate not supplied

Prosthodontic solutions for compromised implant placement.

The various clinical and laboratory procedures for use of auxiliary prefabricated metal screw retention, castable plastic telescopic, and custom laboratory-fabricated systems are presented as adjuncts to implant-supported restorative procedures. These devices aid in the fabrication of predictable and retrievable screw-retained, fixed-detachable implant-supported prostheses for various conditions and combinations of support. Ancillary screw systems are also useful in solving cosmetic problems when implant placement compromises this goal.

Blade Implantation↗
PubMedDate not supplied

Eighteen-month clinical performance of a self-etching primer in unprepared class V resin restorations.

This study evaluated the clinical performance of unprepared Class V resin composites, placed using a self-etching primer and a single-bottle adhesive, over a period of 18 months. Thirty-eight pairs of restorations of Renew hybrid resin composite (BISCO, Inc) were placed using adhesives from the same manufacturer in caries-free cervical erosion/abfraction lesions. Based on insensitivity to air, the dentin in 76% of these lesions was considered to be sclerotic. The restorations were placed without abrasion of tooth surfaces, except for cleaning with plain pumice. One of each pair was placed using Tyrian, a self-etching primer and the other was placed using One-Step, a single-bottle adhesive placed after acid etching. Both the etchant and self-etching primer were applied for 20 seconds. The restorations were clinically evaluated at baseline, 6, 12 and 18 months, using modified Ryge/USPHS criteria. For both adhesives, very low retention of 50% to 56% of the restorations was observed over 18 months, leading to the conclusion that tooth surfaces must receive some additional treatment prior to restoration with these adhesives. No statistically significant difference (p=0.75) between the two adhesives was observed in overall performance, and dentinal sclerosis and axial depth did not appear to be important factors in the study.

Acid Etching, Dental↗
PubMed2001

Preprosthetic clinical crown lengthening procedures in the anterior maxilla.

Clinical crown lengthening procedures (CCLP) are used to enhance aesthetics and/or provide adequate tooth structure for placement and retention of a restoration while respecting the attachment apparatus. When restoration margins extend beyond the biologic width, inflammation and anatomic changes can develop. Anterior CCLP are indicated to increase the labial exposure of the clinical crown and/or the sound tooth structure coronal to the bone crest. Preservation of the interproximal papillae is mandatory to obtain desirable final results in the aesthetic region. This article illustrates various methods of CCLP used to achieve successful oral rehabilitation in the anterior maxilla.

Crown Lengthening↗
PubMedDate not supplied

The effect of luting agents on the retention and marginal adaptation of the CeraOne implant system.

In this study, various luting agents were evaluated to determine their retentive strengths as they pertain to the CeraOne single-tooth implant system. Ten samples of five different luting agents (zinc oxide-eugenol, glass-ionomer cement, hybrid glass-ionomer cement, composite resin, and zinc phosphate) were tested for retentive strength of the CeraOne gold cylinder to the CeraOne abutment. Under the conditions of the experiment, zinc phosphate showed a mean retentive strength 164% greater than that of glass-ionomer cement and 49% greater than that of composite resin cement. Scanning electron micrographs were taken to evaluate the effect of various luting agents on marginal opening. The measurements revealed that zinc phosphate had the greatest marginal opening, although its mean value of 62 microns is within clinically acceptable limits.

Analysis of Variance↗
PubMed1995

A study of the microstructure of some dental retention pins and prefabricated root canal posts.

Pins and root canal posts are generally considered indispensible aids in clinical restorative dentistry. To secure the long-term efficiency of pins and posts, such devices should be of sufficient strength to carry the relevant loads. It is, however, essential that their properties do not decline as a consequence of corrosion, or that corrosion of metallic pins and posts does not cause unfavourable effect in contacting biological tissues. The microstructure of certain commercially available dental retention pins and prefabricated root canal posts has been investigated using optical microscopy and standard metallographic techniques. The specimens were then examined by scanning electron microscope and energy dispersive X-ray analysis (EDAX). The results indicate differences in microstructure and condition between the types examined. The results also showed the presence of included particles in some pins and posts. These differences and the presence of inclusions may have an important bearing on service life and corrosion resistance.

Copper↗
PubMed2004

The retentive effects of pre-fabricated posts by luting cements.

The purpose of this study was to compare the retention of two different pre-fabricated posts cemented to the root canal with four different adhesive luting cements and a zinc phosphate cement. The crowns of 100 freshly extracted human mandibular central and lateral incisors were removed at the cementoenamel junction and divided into two main groups (A = ParaPost and B = Flexi-Post) and further divided into five subgroups to evaluate the effects of five different cements (Rely-X ARC, Panavia F, ParaPost Cement, Flexi-Flow Natural and Adhesor) each with 10 samples. Post-holes were prepared on all of the roots following the manufacturer's instructions. Each sample was placed into a specialized jig and tensile strength tests performed by using testing machine with a crosshead speed of 0.638 cm min(-1) and force applied until failure. The data were analysed with one-way anova (Post Hoc a Scheffe's S test) and two-way anova (P < 0.001). The Flexi-Post dowels had a mean of 54.21 kg (s.d. = 9.37) and demonstrated statistically higher retention than ParaPost dowels with a mean of 33.93 kg (s.d. = 10.69) for all of the cement groups (P < 0.001). In Flexi-Post and ParaPost dowel groups; Rely-X ARC was statistically higher than the Panavia F, ParaPost Cement, Flexi-Flow Natural and Adhesor (P < 0.05). Adhesor was significantly lower than the other subgroups (P < 0.05). Resin luting cements have demonstrated very high tensile strength potential for a strong bond to dentin.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2006

After endo, what supports the crown?

There are two causes of common failures in posts and implants: retention and stress distribution. Implants that were smooth metal cylinders have today become threaded metal cylinders. By using one additional hand-operated instrument, the thread cutter and an additional five minutes of time, a rigid, threaded, metal post can be placed in the root canal to support the remaining coronal dentine. The tooth can frequently be rebuilt as a single unit or a bridge abutment to last for as long as the bone supports the root. To thread or not to thread, was that the question?

Crowns↗
PubMed2001

Total knee arthroplasty using cruciate-retaining kinematic condylar prosthesis.

The purpose of the current study was to evaluate the long-term results of the Kinematic I condylar prosthesis with retention of the posterior cruciate ligament. One hundred sixty-eight total knee arthroplasties in 118 patients (mean age, 65.2 years; range, 21-88 years) were inserted with cement, an all-polyethylene patella, metal-backed tibia, and posterior cruciate ligament retention. Sixty-one patients (86 knees) died, one patient had an above-knee amputation, and three patients (five knees) were lost to followup; therefore, 66 knees (excluding revisions) in 50 patients were available for followup at a mean of 15.7 +/- 1.1 years (range, 14-20 years). Of the entire cohort of 168 knees, 13 have been revised: one for medial femoral condyle fracture, one for tibiofemoral instability, one for femoral and two for tibial component aseptic loosening, four for tibial polyethylene wear, and four for patellar component aseptic loosening. The 15-year survivorship free of any component revision excluding infections was 88.7% (confidence interval, 82%-95%). The 15-year survivorship free of radiographic loosening and/or revision of any component was 85.1% (confidence interval, 78%-92%). The current study shows good function and survivorship of the posterior cruciate-sparing Kinematic I condylar prosthesis at a mean of 15.7 +/- 1.1 years.

Adult↗