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PubMed2000

Bonded retainers--clinical reliability.

Bonded retainers have become a very important retention appliance in orthodontic treatment. They are popular because they are considered reliable, independent of patient cooperation, highly efficient, easy to fabricate, and almost invisible. Of these traits, reliability is the subject of this clinical study. A total of 549 patients with retainers were analyzed with regard to wearing time, extension of the retainer, mean time between failures, operator, and age of patient. The average frequency of breakage or loss was 0.55 per retainer per year. This frequency was dependent primarily on the operator who bonded the retainer and on the extent of the retainer. If the upper canines were involved, reliability was lower. The majority of failures occurred during the first 3 to 6 months. The study showed that bonded retainers represent a highly efficient and reliable retention appliance suited to long-term use.

Adolescent↗
PubMed2001

Evaluation of pre-fabricated root canal posts.

In this in vitro study, properties of a titanium alloy post recently introduced to the market (IntegraPost), were compared with those of a clinically proven stainless steel post (ParaPost). The IntegraPost has a unique, perforated, spherical head and a microknurled shank surface. The posts were tested for rigidity, for retention within the root canals of extracted teeth and for ability to retain composite resin cores. The two post types exhibited similar properties in core and root canal retention, however, the IntegraPost was significantly less rigid than the ParaPost.

Dental Prosthesis Retention↗
PubMedDate not supplied

The effect of serrations on carbon fibre posts-retention within the root canal, core retention, and post rigidity.

The retention in root canals of serrated carbon fibre Composiposts and stainless steel Paraposts was tested under tensile load. Twenty unrestored human roots were endodontically prepared and root filled. Two groups of 10 roots received 1.4-mm Composiposts or 1.25-mm Paraposts luted with a resin cement. The specimens were then embedded in acrylic resin and mounted in an Instron machine. The tensile force (kg) required to dislodge the posts was recorded and analysed with Student's test. The results revealed that there was no significant difference in the retention of either post (P > .05). The rigidty of 10 1.4-mm serrated Composiposts was tested in a three-point bend test in an Instron machine, and the retention of composite cores to 10 of these posts under tensile force was also tested. The results from these tests were compared to previous data from the authors' laboratory and revealed that the serrations significantly reduced the rigidity of the post (P < .001) and increased the retention of a core material (P < .001).

Carbon↗
PubMedDate not supplied

Tensile dislodgment evaluation of two experimental prefabricated post systems.

This study tested the tensile dislodgment forces of two experimental post designs that are threaded 7 mm into the most coronal aspect of the root. Experimental post systems ParaPost XT-7 (XT-7), and ParaPost XT-10 (XT-10) were compared to the Flexi-Post (FP) and to the Standard ParaPost (SP). The XT-7 prototype post measured 7 mm in length, while all other post systems were 10 mm. The XT-7 and the FP are active post systems that are threaded throughout their entire length. The SP is a passive serrated post system, and the XT-10 is a combination active/passive design that has a 7 mm coronal thread with a passive serrated apical end. All systems tested were titanium alloy except the SP system, which was stainless steel. The purpose of this study was to compare an active and a passive post design to the experimental designs of the XT-7 active post and the combined active/passive design of the XT-10. This study clearly demonstrated highest retention for the active post system, least retention for the passive post, with an intermediate retentiveness for the combined design.

Analysis of Variance↗
PubMed1991

Periotest: an objective clinical diagnosis of bone apposition toward implants.

Implant mobility as an indicator of failing close bone apposition is generally known. Whereas a clearly visible mobility can always be correlated with an interposition of soft tissue, the range from a clinically firm implant to just tangible implant mobility represents the actual problem zone. Thirty consecutive patients who had mandibles restored with osseointegrated implants ad modum Brånemark were tested with the Periotest device for damping characteristics of the implants and the peri-implant tissues as a whole. The mean Periotest value (PTV) was -1.74. The characteristics of the mandible, the peri-implant tissue, and the abutment length are the determining factors for the PTV. Fixture length, dolder bar, and length of time in function had no significant influence on the PTV.

Adult↗
PubMed1993

The applicability of osseointegrated implants in the treatment of partially edentulous patients: three-year results of a prospective multicenter study.

Nine clinical centers using the Brånemark System participated in a prospective study of 159 partially edentulous patients between 18 and 70 years of age. Clinical parameters evaluated were Plaque Index, gingivitis, pocket depth, Bleeding Index, tooth mobility, prosthesis stability, and stomatognathic function. Change in bone height around fixtures was measured radiographically. After 3 years, 460 loaded fixtures, supporting 174 prostheses in 139 patients, remain in the study. The complications, failures, and technical problems are presented. After 3 years of this 5-year study, results suggest that implant-based treatment of partially edentulous patients may achieve a success rate comparable to that obtained in edentulous patients.

Adolescent↗
PubMed1993

Quality of fixed prosthodontics after 15 years.

Interviews and/or clinical examinations by means of the California Dental Association quality evaluation system were carried out in a group of persons who had received extensive restorative treatments with fixed partial dentures 15 years before this study. The studied group consisted of 77 persons who agreed to participate from an original group of 150 persons selected at random from the Swedish Dental Insurance System records. Of the original group 20 had died, 17 were not traceable or not able to participate for medical reasons, and 36 declined to participate. Thirty-two per cent of the recorded reconstructions had been lost, and 8% partially lost during the 15-year period. Thirty-five per cent of the reconstructions were rated as Satisfactory, whereas the remaining ones had mixed clinical quality ratings. Failures and Not Acceptable quality ratings were found to be caused mainly by fractures, loss of retention, and/or dental caries.

Adult↗
PubMed1993

Retentive characteristics of an internally threaded post system.

Internally threaded, stainless steel posts 10 mm in length and 1.82 mm in diameter or stainless-steel Para-Post dowels 1.7 mm in diameter were cemented in extracted human teeth with zinc phosphate cement. Titanium alloy screws 1.5 mm in diameter were placed in the internally threaded posts and tensile force was applied to the screws or Para-Post dowels until dislodgment of the post or fracture. The retention of the Para-Post system was significantly greater than the experimental posts. Although all screws exhibited deformation, there was no breakage or distortion of the internally threaded posts or Para-Post dowels. Retention for both systems exceeded reported forces generated in humans.

Analysis of Variance↗
PubMed1993

Comparison of the retention of endodontic posts after preparation with EDTA.

Significant differences in the retention of preformed endodontic posts for endodontically treated teeth were determined with (1) parallel-sided, passively placed Para-Post dowel versus mechanically engaging, threaded Flexi-Post dowel; (2) irrigation of canals with EDTA; (3) cementation with urethane dimethacrylate resinous or zinc phosphate cement. It was hypothesized that EDTA would substantially increase retention by removing the smear layer on the prepared canal wall and create micromechanical retention in the dentin. Extracted teeth were prepared with endodontic posts and divided in groups representing combinations of variables. The forces for post removal and the locations of the retentive bond failures were recorded. The results indicated that EDTA did not significantly affect retention. The Flexi-Post dowel was significantly more retentive than the Para-Post dowel but also exhibited a greater potential for tooth damage compared with the Para-Post dowel during retentive failure loads.

Analysis of Variance↗
PubMed2005

Effect of an adhesive resin luting agent on the dowel-head retention of three different core materials.

STATEMENT OF PROBLEM: A dowel-and-core restoration may fail due to failure at either the dowel-tooth or dowel head-core material interface. Long-term clinical success of a dowel-and-core restoration depends on retention of both the dowel to the tooth and the dowel head to the core material. Thus, strengthening of the dowel head-core interface is important. PURPOSE: This study evaluated the retention between a prefabricated dowel and 3 different core materials with or without a dual-polymerized adhesive resin luting agent. MATERIAL AND METHODS: Sixty prefabricated dowels (Gold Plated Anchorage Post) were divided into 3 groups (n=20) consisting of 1 of 3 core materials, amalgam (Standalloy F), light-polymerized resin composite (Clearfil Ray), or glass ionomer (Chelon-Silver). Each core group was divided into 2 subgroups (n=10), and a dual-polymerized adhesive resin luting agent (Panavia F) was applied to the dowel heads of 1 of these subgroups before application of the core material. The manufacturing procedure was standardized by using a plastic index (4.5-mm internal diameter and 5-mm height) and a custom-made dowel holder, which held the dowel head. Prepared specimens were stored in water at room temperature for 3 months and then loaded to fracture in a universal testing machine with a crosshead speed of 0.05 mm/min until failure. Bond strengths were recorded (MPa). Data were analyzed with 2-way analysis of variance (ANOVA) in a 2 x 3 factorial randomized design (alpha=.05). Afterward, core material differences were computed with 1-way ANOVA for both of the bonded and nonbonded groups. Post hoc multiple comparisons were made with the Dunnett C multiple range test. RESULTS: Dowel-head retention values (MPa) of the tested core materials (mean +/- SD) from the highest to the lowest were as follows: bonded amalgam core, 296.1 +/- 108; bonded composite core, 284.3 +/- 38.3; nonbonded composite core, 177.0 +/- 53.7; nonbonded amalgam core, 128.5 +/- 35.0; bonded glass-ionomer core (GIC), 128.0 +/- 24.5; nonbonded GIC, 61.8 +/- 13.3. Two-way ANOVA revealed significant differences between the core material groups and between the bonded and nonbonded groups (P <.001). The interaction between the core material and bond variables was also significant (P =.018). One-way ANOVA revealed statistically significant differences between the bonded (P <.001) and also between the nonbonded core material groups (P <.001). Post hoc multiple comparisons showed that the dowel-head retention of the GIC was significantly weaker than the post-head retention for amalgam and resin composite, whether bonded or not. CONCLUSION: Within the limitations of this study, the adhesive resin luting agent tested appeared to have a significant strengthening effect on the dowel-head retention of the core materials.

Adhesives↗
PubMed2005

Comparison of two luting agents used for the retention of cast dowel and cores.

PURPOSE: The first purpose of this study was to compare the retentive values of zinc phosphate and Panavia F resin cements when used for luting cast dowel and cores. The second purpose was to determine whether the use of a lubricant when making the resin pattern for a custom dowel and core would have an effect on the final retention of dowels cemented with either zinc phosphate or Panavia F cements. METHODS AND MATERIALS: Sixty-three caries-free extracted single-rooted human teeth were randomly divided into three groups of 21. Root canal preparations were standardized for all 63 teeth. Clinical protocols for fabricating and cementing dowel and core restorations were examined, comparing zinc phosphate and Panavia F resin cements. Direct dowel patterns were fabricated using the Para Post system and cast in a noble metal alloy. Group I dowel spaces were lubricated with GC lubricant prior to dowel pattern fabrication and cleaned with Cavidry solvent before cementing the cast dowel and core with zinc phosphate cement. Group II dowel spaces were rinsed with water only prior to dowel pattern fabrication. The dowels and cores in this group were cemented with Panavia F resin cement. Group III dowel spaces were lubricated with GC lubricant prior to dowel pattern fabrication; the dowel spaces were cleaned with Cavidry solvent before the cast dowel and cores were cemented with Panavia F cement. The tensile force necessary to remove the cast dowel and cores was determined using a universal testing machine. Results were statistically analyzed using one-way ANOVA and Tukey's HSD test. RESULTS: The dowels and cores in Group I had significantly higher retentive values than either of the two Panavia F groups (p< or = 0.001). No difference in retentive values (p > 0.05) was found between dowels luted with either of the lubricating agents in the Panavia F groups. CONCLUSIONS: Zinc phosphate cement had higher retentive values when cementing cast dowel and cores than Panavia F. The type of lubricant used for the resin dowel fabrication (water or GC lubricant that was removed with a solvent) had no effect on the retention of cast dowels cemented with Panavia F.

Analysis of Variance↗
PubMed2002

Retention of posts luted with phosphate monomer-based composite cement in canals obturated using a eugenol sealer.

PURPOSE: To examine the effect post-obturation sequencing had on retention of endodontic posts luted with a phosphate monomer-based resin cement into canals previously obturated using a eugenol-based sealer. MATERIALS AND METHODS: 64 single-rooted teeth were decoronated, and root canals were filed, cleaned, and shaped with a size 5 Gates Glidden drill and 0.12 taper rotary instrumentation. Teeth were then divided into 4 groups of 16 specimens each. Group 1 was not obturated, and served as a control. The other three groups were obturated with gutta percha and a eugenol-based sealer. Post space preparation and post cementation were completed at three different post-obturation intervals - immediate (Group 2), 1 week (Group 3), and 4 weeks (Group 4). Ten-mm deep post spaces were prepared with a size 6 Gates Glidden drill, and size 5 Paraposts were cemented with Panavia 21 OP. Following 48-hour of storage, specimens were mounted in PVC pipe with acrylic, and the posts were removed in tensile mode using a universal testing machine at 1 mm min(-1), with data recorded in kilograms. RESULTS: Group 1 (controls) mean = 61.80, SD = 16.21; Group 2 (immediate) mean = 38.70, SD = 12.97; Group 3 (1 week) mean = 43.15, SD = 14.66; Group 4 (4 weeks) mean = 18.82, SD = 8.00. Using ANOVA and Bonferroni tests, Group 1 demonstrated significantly greater mean retention strength values than Groups 2 and 3 (P < 0.05), which in turn had significantly greater mean retention strength values than Group 4 (P < 0.05).

Analysis of Variance↗
PubMedDate not supplied

Retention and failure morphology of prefabricated posts.

PURPOSE: This study evaluated the effect of cement, post material, surface treatment, and shape (1) on the retention of posts luted in the root canals of extracted human teeth and (2) on the failure morphology. MATERIALS AND METHODS: Posts of titanium alloy (ParaPost XH), glass fiber (ParaPost Fiber White), and zirconia (Cerapost) received one of several surface treatments-sandblasting, CoJet treatment, application of Metalprimer II, or sandblasting followed by silane application-and were then luted in the prepared root canal of human incisors and canines (n = 10). Following water storage at 37 degrees C for 7 days, retention was determined by extraction of the posts. Failure morphology of extracted posts was analyzed and quantified stereomicroscopically. RESULTS: Type of luting cement, post material, and shape of post influenced the retention and failure morphology of the posts. Because of limited adherence of the cement to the root canal, surface treatments did not always have a positive effect on retention. CONCLUSION: Choice of luting cement was critical for all three types of posts. Parallel posts showed superior retention to tapered posts.

Analysis of Variance↗
PubMed1993

Effect of surface design on retention of dowels cemented with a resin.

This study compared the retentive ability of endodontic dowels cemented with a resin when the surfaces of the dowels were varied. Dowels of standardized material, shape, length, and diameter were cemented with an unfilled Bis-GMA resin. Four dowel surface configurations were tested: transverse serrated, crosshatched, threaded, and longitudinal spirals. The results indicated that the dowel surface design can significantly influence the retention of a resin-cemented dowel. Dowels with transverse serrations or crosshatching were retained better than dowels with longitudinal spirals or threads.

Analysis of Variance↗
PubMed1992

A study of 589 consecutive implants supporting complete fixed prostheses. Part I: Periodontal aspects.

Ninety-one consecutive edentulous patients who had been treated by means of fixed prostheses (n = 103) supported by Brånemark implants (n = 589) were examined. Eighteen fixtures (3%) failed to integrate. After a mean loading time of 32 (range 6 to 80) and 38 months (range 5 to 83) for fixtures in the maxilla and mandible, respectively, an additional 12 fixtures lost integration. The cumulative failure rate for individual fixtures after 6 years was 8.4% and 5% for maxillae and mandibles, respectively. Only one patient had to revert to complete dentures. For fixtures in the maxillae, the mean marginal bone loss was 0.7, 0.1, and 0.2 mm for each of the first 3 years of loading, respectively; for fixtures in mandibles, the corresponding values were 0.7, 0.2, and 0.1 mm. The loss in marginal bone height was equal in both jaws and was not related to bleeding on probing or to the preoperative resorption anatomy.

Adolescent↗
PubMed1995

Accuracy and precision in the radiographic diagnosis of clinical instability in Brånemark dental implants.

The aim was to evaluate accuracy and precision in the radiographic diagnosis of clinical instability in Brånemark dental implants. In two clinics specialized in the Brånemark osseointegration technique we identified all patients in whom lack of clinical stability of one or more fixtures had been observed during a 5-year period. Radiographs of these fixtures (n=62) were mixed with radiographs of clinically stable fixtures (n=158). Eight observers were asked to determine whether or not a perifixtural radiolucency was seen by means of a 5-point rating scale expressing the confidence with which the presence or absence of a radiolucency was determined. Receiver operator characteristic analysis was used to calculate the A(z) values and the variability in A(z) values between and within observers was determined. In addition, we evaluated the agreement in rating codes within observers between repeat examinations. The A(z) values (mean=0.844 at the first reading and 0.856 at the second) indicated that the accuracy in radiographic diagnosis of clinical fixture instability was at least as good as that associated with other radiographic tasks such as approximal caries diagnosis and diagnosis of small periodontal bone lesions. Interobserver variability was larger than intraobserver variability. Intraobserver agreement in rating codes was relatively high and less than an average of 6% of all ratings differed with two rating codes or more. Despite the relatively good diagnostic accuracy, the probability of predicting clinical fixture instability from a radiographic examination can be low in populations with a low prevalence of fixtures showing clinical instability.

Alveolar Process↗
PubMed1994

Retention of posts cemented with various dentinal bonding cements.

This investigation evaluated the retention of preformed posts with four different cements: C & B Metabond, Panavia, All-Bond 2, and Ketac-Cem. Sixty intact maxillary canines were selected for the study. The clinical crowns were removed and endodontic therapy done on each root, which was then prepared to receive prefabricated posts. The 60 samples were divided into four groups of 15, and the posts in each group were cemented with one of the four cements. The roots were mounted in acrylic resin blocks and the posts were separated from the canals with an Instron testing machine. Analysis of the forces needed to dislodge the posts with analysis of variance and Student-Newman-Keuls test disclosed that C & B Metabond cement was the most retentive (p < 0.05). No difference in retention was recorded between Ketac-Cem and Panavia cements. All-Bond 2 cement was the least retentive of cements.

Analysis of Variance↗
PubMed1999

Comparison of the retentive and photoelastic properties of two prefabricated endodontic post systems.

This in vitro study compared the retention and photoelastic stress patterns from two loading conditions, vertical (133.2 N, 30 pounds) and oblique at a 26 degrees angle (133.2 N, 30 pounds) for two prefabricated post systems. The post studied were: (1) Flexi-Post (a split-shank threaded post) and (2) C-Post (a carbon fibre bound in an epoxy resin, passive double taper tier post). Two groups with 10 specimens per group were subjected to retentive forces with a universal testing machine (MTS 810 Material Testing Machine). In addition, two photoelastic test blocks were prepared with simulated root canals for each post studied. After cementation the photoelastic blocks were photographed before vertical and oblique loading and after loading. One-way analysis of variance (ANOVA) for retention data revealed a highly significant difference (P<0.0001) between groups. The Flexi-Post had a statistically higher mean retention force of 1180.6 N (265.9 pounds), while the C-Post had a mean of 171.8 N (38.7 pounds). Photoelastic analysis indicated minimal stresses for both the Flexi-Post and C-Post in the unloaded state. The C-Post showed asymmetrical apically stress patterns, while loaded in both states. The multi-tiered system of the Flexi-Post clearly distributes stress symmetrically, while the C-Post distributes stresses asymmetrically. The symmetric, even stresses and statistically higher retentive strength for Flexi-Post are more favourable than the asymmetric, uneven stresses and relatively low retentive strength for the C-Post.

Analysis of Variance↗