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PubMed2006

The comparison of provisional luting agents and abutment surface roughness on the retention of provisional implant-supported crowns.

STATEMENT OF PROBLEM: In immediate implant loading, it is important to keep provisional restorations in place during early-phase healing. Current luting agents for provisional restorations may provide inadequate retention, creating a clinical challenge. PURPOSE: This study compared the retention of provisional autopolymerizing acrylic resin implant-supported single restorations with combinations of different implant abutment surface conditions and provisional luting agents. MATERIAL AND METHODS: Thirty solid titanium implant abutments (ITI), 4 mm high, were divided into 3 groups. Ten abutments were unaltered, 10 were airborne-particle abraded with 50-microm aluminum oxide, and 10 were roughened with a medium-roughness diamond rotary cutting instrument. Thirty implant analogs (ITI) were mounted in autopolymerizing acrylic resin blocks. A solid titanium implant abutment was placed in each implant analog and torqued to 35 N.cm. After fabrication of 4 provisional acrylic resin crowns for each abutment, provisional luting agents TempBond, TempBond NE, Life, and Zone were used to secure the provisional crowns to the respective abutments. All specimens were luted with one of the provisional luting agents for a given test. After ultrasonic cleaning of the abutments, another provisional crown was luted with another luting agent. All specimens were stored in 100% humidity environment for 1 day at 37 degrees C prior to testing. Each provisional acrylic resin crown was pulled from the abutment with a 500-kg load cell in a universal testing machine at a crosshead speed of 0.5 cm/minute, and tensile strength was recorded (N). Data were analyzed using analysis of variance (ANOVA) and the Scheffe test (alpha=.05). RESULTS: Tensile strength was significantly higher for Life and TempBond NE than for TempBond and Zone, regardless of the surface conditions (P=.0001). The result of the 2-way ANOVA indicated that a significant interaction existed between the provisional luting agents and surface conditions (P=.0039). TempBond NE showed significantly higher tensile strength when combined with airborne-particle-abraded surfaces compared to other combinations (P=.011). However, no difference was found in tensile strength of Life and Zone between different combinations. The tensile strength of TempBond was lower when used with the unaltered surface compared to other combinations (P=.001). CONCLUSION: Surface modification of an implant abutment by airborne-particle abrasion or diamond rotary cutting instrument did not improve retention of a provisional acrylic crown when Life or Zone was used as the luting agent. Airborne-particle abrasion may be an effective method to increase retention of a provisional acrylic crown when TempBond NE is used.

Acrylic Resins↗
PubMed2004

Treatment options for the edentulous mandible: clinical application of the two-implant overdenture.

Edentulism is a public health concern that affects millions of individuals. While this condition has been treated for years with implant-supported hybrid prostheses, this modality does not always represent the optimal restorative solution for all patients. The two-implant mandibular overdenture provides greater retention than does a conventional mandibular denture and, due to its cost and efficacy, can significantly improve an edentulous patient's quality of life. This article reviews the nutritional and social aspects of edentulism in affected patients and its treatment with two-implant overdentures.

Dental Prosthesis Design↗
PubMedDate not supplied

Single-tooth replacement with the Frialit-2 system: a retrospective clinical analysis of 146 implants.

PURPOSE: This study was intended to provide a report of experience and results with Frialit-2 implants used for single-tooth replacement. MATERIALS AND METHODS: Over a 7-year period (1994-2000), 146 single-tooth implants (84 maxilla, 62 mandible) were placed in 112 patients (67 females, 45 males; 31.2 +/- 16.4 years). The sites included maxillary anterior teeth (n = 38) as well as the mandibular premolars and molars (n = 57). Ninety-three crowns were cemented and 53 crowns were screw mounted (22 with vertical, 31 with horizontal screws) on standard abutments. The follow-up time varied between 3 and 80 months (35.8 +/- 16.5 months). RESULTS: Two implants (1.4%) were lost, 1 during early loading and the other after 6 years. The most frequent prosthetic complication was isolated crown loosening of cemented crowns requiring recementation of 9 crowns (9.9%). Crowns with vertical screws showed no crown and/or screw loosening. Four crowns (2.8%) were replaced because of ceramic fracture. DISCUSSION: Peri-implant soft tissue condition, bone resorption, and Periotest values indicated satisfactory results. The cumulative implant survival rate during the follow-up period was 97.3%, and that of the crowns 96.4% (total cumulative survival rate 93.7%). CONCLUSIONS: With the low number of abutment screw loosenings (3.5%), the deep internal hexagonal retention compared favorably to external retention methods. The predominant use of long implants (98.4% > or = 13 mm) allowed a favorable implant/crown ratio with the potential for problem-free, long-term results.

Adult↗
PubMed1998

Retrievable cemented implant restorations.

Prostheses can be attached to implants or implant abutments by screw retention, cementation, or with the use of set-screws. The indications for non-screw-retained restorations are discussed with respect to implant body position and surgical limitations for implant placement. The advantages and disadvantages of each method are outlined. A technique that uses a screw threaded into the implant restoration to displace the cemented restoration is presented. Use of this technique will allow predictable removal of the cemented restorations without damage to the prosthesis or abutment.

Cementation↗
PubMed1997

Repair of a fractured implant-supported mesiostructure bar.

Osseointegrated implants are often used for mandibular denture retention. Although clinical success rates are high, complications can occur. A specific clinically relevant example of a fractured bar is presented along with a procedure for its repair. This procedure allows the repair to be done in a timely and cost-efficient manner.

Dental Casting Technique↗
PubMed1997

A randomised clinical trial on the influence of splinted and unsplinted oral implants in mandibular overdenture therapy. A 3-year report.

A randomised clinical trial was performed to investigate whether there is a need or advantage to splint two implants in the mandible retaining a hinging overdenture. Furthermore, patient satisfaction was evaluated for different attachment systems retaining the overdenture. Thirty-six edentulous patients were randomised into three groups of equal size and treated with either magnets, ball attachments or straight bars (reference group). After 3 years of observation no implants were lost in any of the groups. Besides, no statistically significant differences were noted for the peri-implant outcome. Although the bar group presented the highest retention force, the general satisfaction of the patients in the three groups did not differ. The patients with bar retentions showed less prosthetic complications of the retention elements but more at the level of the denture-supporting mucosa. Finally, the clinical outcome of all groups confirms that overdenture treatment demands regular controls with limited time intervals.

Adult↗
PubMed1999

Clinical methods for adjusting retention force of cast clasps.

Careless adjusting methods to increase or decrease retention by grinding, polishing, or bending the clasp arm can lead to instability of the removable partial denture, damage to the surrounding tissues, and fracture of the clasp arm. This article describes systematic evaluation criteria and adjusting methods of retention force of a cast clasp. Excessive retention can be reduced by using a proper adjustment method, which depends on the cause. Poor retention can be increased temporarily, but it will decrease again. Evaluations and adjustment of poor retention will contribute to the diagnosis of the cause and will establish clinical and laboratory procedures that will lead to making clasps with proper retention in the future.

Dental Clasps↗
PubMed2003

Implant therapy to improve quality of life.

Excessive alveolar bone atrophy often confounds a conventional therapy with complete dentures. Implant therapy has found a way to solve the problem through enhanced stability and retention, thus increasing its functionality, leading to improved patient satisfaction and a higher quality of life. This article describes an implant-supported restoration of a patient with reduced oral health and high Oral Health Impact Profile values (OHIP-14). Upon improvement of oral hygiene and the compliance of the patient, the residual dentition was extracted and four implants were inserted, both in the maxillary and the mandibular arches. After the healing period was completed, two implant-supported prostheses with rigid bars for retention were fabricated. The patient's esthetics, phonetics, and masticatory function were properly restored at the time of delivery. A significant improvement in the patient's quality of life was noticed. In comparison to conventional dentures, the implant-supported overdentures offer better function and comfort for many patients.

Aged↗
PubMed2005

Retentive strength of metal copings on prefabricated abutments with five different cements.

BACKGROUND: Despite their wide use in implant dentistry, there is insufficient information concerning the retentive strength of cement-retained superstructures. PURPOSE: This study compared the retentive strength of metal copings on prefabricated abutments with five different luting cements. MATERIALS AND METHODS: Eight prefabricated abutments were placed on titanium screw implants torqued to 35 Ncm. Metal copings were cast with Au-Pt-Pd alloy (DeguDent Universal, Degussa, Hanau, Germany) using burnt-out plastic copings. Cements used were zinc oxide-eugenol-free temporary (ZO), zinc phosphate (ZP), glass ionomer (GI), resin-reinforced glass ionomer (RG), and composite resin (CR) cements. Retentive strength was measured with a universal testing machine. The means of each group were compared by one-way analysis of variance and Tukey-Kramer multiple-comparison intervals at a significance level of p < .05. RESULTS: The mean +/- SD retentive strength of the cements in Newtons was ZO 56 +/- 12 (Tukey group C), ZP 158 +/- 79 (Tukey group B), GI 132 +/- 29 (Tukey group B), RG 477 +/- 52 (Tukey group A), and CR 478 +/- 50 (Tukey group A). CONCLUSION: The retentive strength of metal copings on implant abutments is somewhat different from those of conventional cemented restorations on natural teeth. These differences may be influenced by differences in surface roughness and the height of the abutment.

Composite Resins↗
PubMed2003

The effects of abutment taper, length and cement type on resistance to dislodgement of cement-retained, implant-supported restorations.

PURPOSE: The purpose of this study was to compare the effect of 20 degrees and 30 degrees of total occlusal convergence (TOC), the occlusocervical dimension, and the type of cement on the tensile resistance to dislodgement of cement-retained, implant-supported restorations. MATERIALS AND METHODS: Cylindrical preparations with TOC angles of 20 degrees and 30 degrees and occlusocervical dimensions of 4 mm (S) and 8 mm (L) were made through a machining process. The cylinders had a shoulder finish line of 1.0 mm in depth. Eight impressions were made of each machined cylinder and poured in type IV dental stone, for a total of 32 dies. Die spacer was applied to each die. A master wax pattern was designed, and the 32 wax patterns were marginated, invested, and cast in type IV gold alloy (n = 8). The gold crowns were cemented with Fleck's cement (zinc phosphate cement), Temp-Bond (zinc oxide eugenol cement), Temp-Bond plus Vaseline (30% by weight), and IMProv temporary cement (acrylic/urethane cement) under a 10-kg load and placed in a humidor at 37 degrees C for 1 hour before testing. A uniaxial tensile force was applied to the crown using an Instron machine with a crosshead speed of 5 mm/min until cement failure occurred. Analysis of variance models were fit to determine the effect of TOC, occlusocervical dimension, and cement type of the restorations on the mean tensile strength. RESULTS: For each type of cement, the mean tensile strengths were significantly higher at 20 degrees of TOC and 8 mm of occlusocervical dimension compared with the other preparations. At this preparation, IMProv had the highest mean tensile resistance to dislodgement (47.7 +/- 8.4 kg), followed by Fleck's (38.2 +/- 8.8 kg), Temp-Bond (35.9 +/- 4.4 kg), and Temp-Bond plus Vaseline (8.2 +/- 2.2 kg). No statistically significant difference was observed between Temp-Bond and Fleck's zinc phosphate cement when 20 degrees of TOC and 8 mm of occlusocervical dimension was used. There was no statistical difference in the mean tensile resistance to dislodgement for Temp-Bond plus Vaseline with different preparation designs (p > 0.05) except when 20 degrees of TOC and 8 mm of occlusocervical dimension was used. The mean tensile strength was significantly different between Temp-Bond and Temp-Bond plus Vaseline for each of the 4 preparation designs (p < 0.05). Among the cements tested, IMProv exhibited higher values, which were statistically different (p < 0.05). Restorations with greater occlusocervical dimension and less TOC exhibited higher tensile resistance to dislodgement. CONCLUSIONS: Preparations with 20 degrees of TOC and 8 mm of occlusocervical dimension had significantly higher mean retentive values for all of the cements tested. Significant differences in mean tensile strength were observed, with the highest tensile resistance seen with IMProv, followed by Fleck's cement, and the lowest tensile resistance seen with Temp-Bond plus Vaseline.

Analysis of Variance↗
PubMed2002

Comparative evaluation of casting retention using the ITI solid abutment with six cements.

OBJECTIVE: The purpose of this study was to test the retention of metal copings fabricated to fit on the one-groove, one flat-sided solid titanium abutment using six different cements. MATERIALS AND METHODS: Ten hollow screw 3.8 mm ITI implants were mounted in acrylic resin blocks. A solid titanium abutment was placed on each implant and torqued at 35 Ncm. Prefabricated burn-out caps were placed on the titanium abutment and wax loops added to the occlusal surface to allow for subsequent retention testing. All plastic caps were embedded in phosphate-bonded investment and cast with noble alloy. Castings were inspected for surface irregularities using a stereomicroscope at 10x magnification. The six cements were: 1) eugenol-free zinc oxide (Temp Bond NE); 2) zinc-oxide eugenol (IRM); 3) zinc phosphate (Hy-Bond); 4) resin-modified glass ionomer (Protec Cem); 5) zinc polycarboxylate (Durelon) and 6) 10-methacryloyloxydecyl dihydrogen phosphate resin (Panavia 21). After cementation, implant-abutment-casting assemblies were stored for 24 h in 100% humidity. Samples were subjected to a pull-out test using an Instron universal testing machine at a crosshead speed of 0.5 mm/min. The load required to de-cement each coping was recorded and mean values for each group calculated. Means and standard deviations of loads at failure were analyzed using ANOVA and a Tukey studentized test. Statistical significance was set at P < or = 0.05. RESULTS: The mean values (+/- SD) of loads in kilograms at failure (n = 10) for the various cements were as follows: Temp Bond 3.18 (+/- 1.1) (Tukey group D), IRM 9.25 (+/- 3.83) (Tukey group CD), HY-Bond 10.9 (+/- 6.52) (Tukey group C), Protec Cem 18.98 (+/- 6.23) (Tukey group B), Durelon 23.55 (+/- 4.29) (Tukey group B) and Panavia 21, 36.53 (+/- 8.1) (Tukey group A). Means with the same letter in the Tukey grouping are not significantly different. CONCLUSIONS: The retention values of castings cemented to ITI solid abutments have not been reported in the literature. Within the limitations of this in vitro study, the results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the castings. This ranking is somehow different than that obtained when the same cements are used on natural teeth. The material and surface characteristics of the implant abutment are likely responsible for this difference. Cement retention values obtained from studies that use teeth as abutments may be misleading when used in cement-retained implant-supported crowns. It is at the clinician's discretion to use a certain type of cement, based on the situation at hand.

Analysis of Variance↗
PubMedDate not supplied

The importance of dental implants.

Implant dentistry has evolved into the mainstream of restorative practices all over the world. Maintenance of bone after tooth loss to improve or maintain facial esthetics and improved retention, function, and performance of removable restorations are only some of the advantages for the edentulous patient. No longer are implants considered only when traditional restorations cannot be fabricated. Evidence-based reports indicate implant restorations last longer than those on teeth and the abutment teeth are at less risk of loss or complication.

Adult↗
PubMed1998

New ways of designing suprastructures for fixed implant-supported prostheses.

The replacement of lost teeth and tooth-bearing tissues with implant-supported prostheses often forced both dentist and technician to choose removable overdentures because they were the only treatment modality possible. By means of a clinical case, this article demonstrates a new approach in framework design that not only expands the limitations of conventional ceramometal implant prostheses, but also eliminates a great number of the hazards that cause implant failure with a new type of suprastructure. The technique enables both the clinician and the technician to apply all of the esthetic possibilities of tooth-supported metal ceramic crown and bridge techniques. This technique combines screw and cementation retention without changing the original treatment protocol. A new casting technique introduced by Sonntag and a new specially developed alloy was used. Essentially, the reconstructive body has been broken down into a screw-retained soft tissue/bone-replacing part using a one-piece casting technique, and a crown-replacing part to be provisionally cemented with a large variety of new possibilities.

Aged↗
PubMed2003

A crown venting technique for the cementation of implant-supported crowns.

With the increased use of implant systems for the replacement of single teeth, some dental practitioners are choosing to permanently cement the final restoration instead of using the screw-retention modality. Many of these restorations have subgingival margins; therefore, the cementation technique becomes a critical procedure because incomplete seating of the restoration or excess cement can be lodged in the gingival sulcus. The use of a cement escape way or venting technique for the cementation of an implant-supported restoration is described.

Cementation↗
PubMed2007

Cementable implant crowns composed of cast superstructure frameworks luted to electroformed primary copings: an in vitro retention study.

OBJECTIVE: The aim of this in vitro study was to investigate, on ITI solid abutments, the retention values of single crowns fabricated using an alternative prosthetic solution: secondary cast superstructure luted to an electroformed primary coping. MATERIALS AND METHODS: Fifty standard 4.1 mm ITI implants and 5.5 mm high ITI machined abutments were assembled and mounted in acrylic resin. Implant/abutment assemblies were randomly divided into two groups. In the test group, primary galvanic caps were directly fabricated on implant abutments (A.G.C. Micro machine), and a secondary cast noble alloy superstructure was luted on each primary galvanic cap with a resin cement (Nimetic Cem). In the control group, prefabricated burn-out caps were used for casting the metal frameworks. Test and control crowns were cemented using a resin cement (Panavia 21). After storage at 37 degrees for 24 h, the specimens were subjected to a pull-out test using an Instron universal testing machine. The load required to dislodge each sample and the respective mode of failure were recorded. Means and standard deviations of loads at failure were analyzed using ANOVA. Statistical significance was set at P< or =0.05. RESULTS: The retention values (+/-SD) of loads at failure were 67.26 (+/-16.61) for the test group and 44.03 (+/-9.45) for the control group. In the test group no separation occurred between the electroformed (galvanic) primary cap and the secondary superstructure. CONCLUSIONS: The results showed that this prosthetic solution is superior on retentive performance than the conventional cast framework. An added clinical advantage of this novel method is its potential to provide a totally passive fit. Further in vitro and in vivo studies involving multiple-unit restorations are needed in order to more generally validate this prosthetic concept.

Cementation↗
PubMed2004

Cement fixation and screw retention: parameters of passive fit. An in vitro study of three-unit implant-supported fixed partial dentures.

It is generally assumed that passively fitting superstructures are a prerequisite for long-lasting implant success. In the study presented, the strain development of three-unit implant fixed partial dentures (FPDs) was evaluated at the bone surrounding the implant and on the superstructure using a strain gauge technique. Six groups of three-unit FPDs representing the commonly used techniques of bridge fabrication were investigated with 10 samples each, in order to quantify the influence of impression technique, mode of fabrication and retention mechanism on superstructure fit. Two ITI implants (Straumann, Waldenburg, Switzerland) were anchored in a measurement model according to a real-life patient situation and strain gauges were fixed mesially and distally adjacent to the implants and on the bridge pontics. The developing strains were recorded during cement setting and screw fixation. For statistical analysis, multivariate two sample tests were performed setting the level of significance at P=0.1. None of the investigated bridges revealed a truly passive fit without strains occurring. About 50% of the measured strains were found to be due to impression taking and model fabrication, whereas the remaining 50% were related to laboratory inaccuracies. The two impression techniques used did not reveal any significant differences in terms of precision. Both modes of fixation--i.e. cement and screw retention--provoked equally high stress levels. In the fabrication of screw-retained FPDs, similar results were obtained from the use of burn-out plastic copings and the technique of casting wax moulds to premachined components. Bonding bridge frames onto gold cylinders directly on the implants significantly reduces strain development.

Aged↗
PubMed2004

An alternative method for the fabrication of customised abutments for single tooth replacements. A clinical follow-up after 18 months.

The present paper describes an alternative method (The Cresco ST-method) for the fabrication of customised abutments designated for implant supported single-tooth (ST) replacements. The method is based on the conventional lost wax technology. 29 ST-replacements/crowns fabricated according to the method were tested/evaluated clinically during an 18 months period. The test was focused on mechanical complications. All crowns were supported by Cresco solid screw implants. Only one mechanical complication (retention screw loosening) was reported during the observation period. Based on the results it was concluded that the Cresco ST-method for fabrication of customised abutments is accurate and reliable. The influence of the interlocking features between implant and abutment and the advantages with customised abutments were discussed.

Adult↗
PubMed1999

Classification system for implant-supported overdentures.

A classification system for implant-supported overdentures is proposed in this article. Various types of implant-supported overdentures have been described in the literature, but there is considerable difference in the function of these designs. For example, an overdenture supported by freestanding implants does not have the retentive elements provided by a bar and, therefore, is less retentive than an overdenture supported by a straight bar. If more than two implants are configured in an arch, and if indirect retention is incorporated into the bar and overdenture design, function is improved over that of a straight-bar design. Another classification of overdenture is one that receives all of its support from an implant-supported bar with tissue contact to provide a mucosal seal. This tissue contact does not provide any actual support. By accepting and using this classification system, the clinician can design an overdenture that is appropriate for the functional requirements of the patient being treated.

Dental Prosthesis Design↗