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PubMed2006

Fabrication of a cement- and screw-retained multiunit implant restoration.

Retrieval of cemented implant restorations can be difficult for both the patient and the dentist. The method described in this article combines the advantages of cement- and screw-retained restorations. Abutment screws can be easily reached by the screw access channel prepared in the waxing phase; the restoration can be retrieved without destroying the implants and prosthesis. This article describes a simple and reliable method to fabricate a retrievable cemented prosthesis.

Cementation↗
PubMed2004

Evaluation of the adaptation interface of one-piece implant-supported superstructures obtained in Ni-Cr-Ti and Pd-Ag alloys.

Several formulations of alternative alloys have been proposed for the substitution of gold-based alloys used in Dentistry. Recently, a Ni-Cr-Ti-based alloy has been introduced. The purpose of this work was to verify the marginal adaptation obtained with one-piece superstructures for implant-supported prostheses obtained in Ni-Cr-Ti alloy, compared to a semi-noble alloy Pd-Ag. Eight superstructures for each alloy were produced over 4 implants in the anterior region of the mandible. The superstructures were placed in a torquemeter and the fixation screw of implant #1 was tightened with a 20 Ncm load with the others loosened (Sheffield test). The unfitness (in mm) was measured using a three-dimensional optical measurer in each implant, in the buccal and lingual aspects. The obtained data were submitted to statistical analysis by the analysis of variance and Tukey's test at 5% level. Significant differences were found for the factors material (p< or =0.05), with Ni-Cr-Ti pieces better than Pd-Ag ones, and implants (p< or =0.01). There were no significant differences for the factor position and interactions among factors (p>0.05). Based on the analysis of the data, it is possible to conclude that the Ni-Cr-Ti alloy makes possible the obtainment of one-piece implant-supported superstructures with a smaller misfit compared to the one obtained in Pd-Ag alloy, traditionally indicated for this situation. Additional tests may verify the superiority of the Ni-Cr-Ti alloy.

Chromium Alloys↗
PubMed2001

Internal contamination of a 2-component implant system after occlusal loading and provisionally luted reconstruction with or without a washer device.

BACKGROUND: Microbial internal contamination of oral implants has been suggested as being responsible for inflammatory infiltration of peri-implant tissues at the fixture-abutment interface of 2-stage and 2-component implant systems; it is also considered as a potential source of pathogens. The present in vivo study evaluated contamination of the inner abutment-implant retaining screw, after occlusal loading and provisionally-luted reconstruction with or without a washer device. METHODS: Eight 2-component oral implants sealed with an o-ring silicon washer device and 9 without a seal were placed in 7 patients with high oral hygiene standards. Two months after prosthetic reconstruction, crowns and internal screws were removed, and organic and inorganic screw contamination was examined by scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS) analysis. RESULTS: An amorphous and crystalline contamination, suggestive of calcium and phosphate compounds, was seen on all screw surfaces. Microbial contamination was more frequently observed in the unsealed group. No differences in bacterial morphotypes were observed between the sealed and unsealed implants. Cocci were the most representative morphotypes, while rods were seldom seen. CONCLUSIONS: In clinical situations, leakage occurs at the implant-abutment interface, although bacterial contamination is limited in patients with high oral hygiene standards. Contamination may be reduced by using a washer device.

Analysis of Variance↗
PubMed2002

Implant placement in maxillary first premolar fresh extraction sockets: description of technique and report of preliminary results.

BACKGROUND: The postextraction morphology of the maxillary first premolar extraction socket presents a number of challenges to clinicians seeking ideal implant position, including the morphology of the lateral walls of the extraction socket and the presence of the interradicular septum. A technique for simplification of implant placement at the time of maxillary first premolar extraction is described. METHODS: Sixty-three implants were placed in maxillary first premolar immediate extraction sockets in 57 patients (36 females and 21 males), utilizing a technique which includes removal of residual interradicular bone prior to preparing the osteotomy, use of the removed interradicular bone in the extraction socket defect surrounding the implant, and swaging of the buccal and palatal osseous plates against the implant. RESULTS: All implants demonstrated clinical stability upon uncovering. Forty-one of the implants placed have been restored and in function for a period of up to 2 years. CONCLUSIONS: The technique described affords a simplified and predictable manner for placement of implants into immediate maxillary first premolar extraction sockets. Further studies should be carried out to document long-term success and failure rates of implants placed utilizing this technique, and subsequently restored.

Adult↗
PubMed2004

Osseointegration in a sinus augmented with bovine porous bone mineral: histological results in an implant retrieved 4 years after insertion. A case report.

BACKGROUND: A subject of controversy in implant dentistry is what is the most appropriate material for sinus augmentation. Little is known about the healing pattern and the osseointegration processes at the interface of implants placed in different grafting materials in man. Bovine porous bone mineral (BPBM) is a xenogenic material similar to human cancellous bone with a high biocompatibility and osteoconductivity. METHODS: A 50-year-old patient presented a posterior left maxilla with an insufficient bone height for implant insertion. In January 1999, a sinus lifting procedure was performed and the left sinus was augmented with BPBM; in November 1999, three implants were inserted, and in July 2000 a fixed prosthetic restoration was positioned. In June 2003 the connecting screw of the middle implant fractured and it was decided to remove the implant using a 5 mm trephine bur. RESULTS: All BPBM particles were surrounded by newly formed bone. No BPBM particle was in direct contact with the implant surface, and between the implant surface and the particles there was newly-formed bone. BPBM seemed to undergo a very slow resorption; the particles constituted 36% +/- 3% of the peri-implant tissues. The bone-implant contact percentage was 72% +/- 4%. CONCLUSIONS: In our specimens, we found an intimate, direct contact between bone and implant without an interposition of the graft material particles. A very high bone-to-implant contact percentage was present. Our results show that the slow resorption of the graft particles did not jeopardize the osseointegration of the implant.

Animals↗
PubMed2006

The effects of interimplant distances on papilla formation and crestal resorption in implants with a morse cone connection and a platform switch: a histomorphometric study in dogs.

BACKGROUND: Implant esthetics have been the focus of attention for the last few years, and one of the most important points is the effect that interimplant distances can have on papilla formation and bone loss. The aim of this study was to evaluate the effect that distances of 1, 2, and 3 mm between implants after prosthetic restoration will have on crestal bone resorption (from the top of the implant to the bone crest [TI-BC]) and bone resorption (from the top of the implant to the first bone-to-implant contact TI-BIC) in two-stage implants used in a submerged and non-submerged protocol. METHODS: The mandibular bilateral premolars of seven dogs were extracted, and after 12 weeks, each dog received eight implants. The implants were placed so that three interimplant contact points were created, with 1-mm (group 1), 2-mm (group 2), and 3-mm (group 3) distances constructed on each side. The sides and the position of the groups were randomly selected. After 12 weeks, the implants received metallic prostheses with 5 mm between the contact point and the bone crest. After 8 weeks more, the animals were sacrificed. RESULTS: The TI-BC was 0.20 and 0.18 mm for group 1, 0.15 and 0.14 mm for group 2, and 0.15 and 0.15 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BC was 0.16 mm for non-submerged and 0.16 mm for submerged implants. The TI-BIC was 0.32 and 0.30 mm for group 1, 0.19 and 0.21 mm for group 2, and 0.30 and 0.24 mm for group 3 for non-submerged and submerged implants, respectively. At the proximal region, the TI-BIC was 0.26 mm for non-submerged and 0.25 mm for submerged implants. There was no statistical difference for any of the parameters (analysis of variance [ANOVA]). CONCLUSION: Distances of 1, 2, and 3 mm between implants do not result in statistically significant differences on TI-BC and TI-BIC around submerged or non-submerged implants with a Morse cone connection and a platform switch.

Alveolar Bone Loss↗
PubMedDate not supplied

Clinical experiences with laser-welded titanium frameworks supported by implants in the edentulous mandible: a 5-year follow-up study.

PURPOSE: The purpose of this study was to report the 5-year clinical performance of implant-supported prostheses with laser-welded titanium frameworks and to compare their performance with that of prostheses provided with conventional cast frameworks. MATERIALS AND METHODS: On a routine basis, a consecutive group of 824 edentulous patients were provided with fixed prostheses supported by implants in the edentulous mandible. In addition to conventional gold-alloy castings, patients were at random provided with 2 kinds of laser-welded titanium frameworks. In all, 155 patients were included in the 2 titanium framework groups. A control group of 53 randomly selected patients with conventional gold-alloy castings was used for comparison. Clinical and radiographic 5-year data was collected for the 3 groups. RESULTS: All followed patients still had fixed prostheses in the mandible after 5 years. The overall cumulative success rates were 95.9% and 99.7% for titanium-framework prostheses and implants, respectively. The corresponding success rates for the control group were 100% and 99.6%, respectively. Bone loss was 0.5 mm on average during the 5-year follow-up period. The most common complications for titanium frameworks were resin or tooth fractures, gingival inflammation, and fractures of the metal frames (10%). One of the cast frameworks fractured and was resoldered. Loose and fractured implant screw components were few (< 1%). CONCLUSION: Even though the cast frameworks had a higher success rate, the overall titanium framework treatment result was well in accordance with the result of the control group. The test groups performed better after clinicians had gained some experience with the technique, and laser-welded titanium frameworks seem to be a viable alternative to conventional castings in the edentulous mandible.

Adult↗
PubMedDate not supplied

A 3-year prospective multicenter follow-up report on the immediate and delayed-immediate placement of implants.

A total of 264 implants was placed in 143 patients using different immediate or delayed-immediate implant placement techniques in 12 different centers participating in a prospective multicenter study. The reason for tooth extraction was evaluated; bone quality and quantity were classified; socket depths were registered; and data on implant type, size, and position were collected. One hundred thirty-nine suprastructures were placed on 228 implants in 126 patients. A follow-up evaluation was done on 125 patients after 1 year of loading and on 107 patients after 3 years of loading. Clinical parameters (bleeding or not bleeding, pocket depth, and implant mobility) were evaluated after 1 and 3 years, and the marginal bone level after 1 year of loading was measured on radiographs. Clinical comparisons were performed to evaluate implant loss in relation to implant type, size, position, bone quality and quantity, socket depth, reason for tooth extraction, and placement method. In addition, life table analysis was done for cumulative implant survival rates. There was no clinical difference with respect to socket depth or when comparing the different placement methods. A higher failure rate was found for short implants in the posterior region of the maxilla and when periodontitis was cited as a reason for tooth extraction. Mean marginal bone resorption from the time of loading to the 1-year follow-up was 0.8 mm in the maxilla and 0.5 mm in the mandible. Over a period of 3 years, the implant survival rate was 92.4% in the maxilla and 94.7% in the mandible.

Bone Density↗
PubMed1998

Long-lasting osseointegration of immediately loaded, bar-connected TPS screws after 12 years of function: a histologic case report of a 95-year-old patient.

The present case report provides histologic findings on four titanium plasma-sprayed screw implants after 12 years of incorporation and functional load in a 95-year-old patient. At the time of implant placement, the four implants were immediately connected with a bar and functionally loaded with a bar-supported overdenture. The histologic analysis demonstrated excellent osseointegration in either cortical or cancellous bone for all implants. The histomorphometric analysis showed direct bone-implant contact of approximately 70% to 80% at the interface. Close to the implant surface, signs of ongoing bone remodeling activities were present. The present histologic case report confirms the validity of the applied treatment concept--to immediately load titanium implants with a titanium plasma-sprayed surface in the anterior region of the mandible--if a minimum of four implants can be inserted and if the four implants are splinted with a bar.

Aged↗
PubMed1999

New techniques in spark erosion: the solution to an accurately fitting screw-retained implant restoration.

How accurate is today's method of casting in the dental laboratory? Normally it is good enough, but what happens if the dental technician is confronted with an extensive restoration or has to deal with the precision of prefabricated implant abutments? In either case, he or she is headed for trouble. So what is to be done, especially if both of these components come together? The force transferred to the osseointegrated endosseous implants is naturally undesirable and the main reason for premature loss of the implants. The present article describes the production of an implant-related restoration for a 50-year-old patient. The plans were to make a partially removable, implant abutment-- connected, base metal framework and to administer spark-erosion machining to achieve a passive fit.

Dental Casting Technique↗
PubMedDate not supplied

Strength and mode of failure of single implant all-ceramic abutment restorations under static load.

The strength and mode of failure of three different designs of custom-made all-ceramic implant abutments fabricated by milling of In-Ceram sintered ceramic blocks were compared with the conventional CeraOne system under static load. Four test groups were formed with different locations of abutment screws. In three test groups, In-Ceram crowns were fabricated for placement on the all-ceramic abutments, and in one test group, a veneer porcelain was fired directly on the abutment; crowns in the control group were fabricated using the CeraOne system. Ten-mm-long Brånemark implants were placed into a brass block that allowed loading at a 30-degree angle to the long axis. The test group in which the veneer porcelain was fired directly on the all-ceramic abutments was the weakest, and it showed fractures at a mean value of 236 N. The fracture strength of the three other test groups was dependent on the extension of the crown margin relative to the location of the screw head. The test group that had the screw on the top compressing the entire ceramic abutment showed a mean value of 422 N that was similar to the results that were achieved with the CeraOne system (427 N). The weakest link in the all-ceramic single implant restorations was the abutment screw in which the bending began at approximately 190 N.

Aluminum Oxide↗
PubMedDate not supplied

Implant/tooth-connected restorations utilizing screw-fixed attachments: a survey of 3,096 sites in function for 3 to 14 years.

Numerous problems have been reported following various therapies used to attach natural teeth to implants beneath a fixed prosthesis. This study documents the results of 843 consecutive patients treated with 1,206 natural tooth/implant-supported prostheses utilizing 3,096 screw-fixed attachments. After 3 to 14 years in function, only 9 intrusion problems were noted. All problems were associated with fractured or lost screws. This report demonstrates the efficacy of such a treatment approach when a natural tooth/implant-supported fixed prosthesis is contemplated.

Dental Abutments↗
PubMed1999

Evaluation of the implant master cast by means of the Periotest method.

Accurate master casts are essential for the construction of implant-supported prostheses with a precision of fit. The stability of the abutment replicas in the master cast is critical in the accurate reproduction of the patient's oral presentation. The Periotest method is an objective method of quantifying mobility in a tooth and implant. Eighteen gypsum implant master casts containing two brass abutment replicas per cast were evaluated. The abutment replicas were measured three times each for a total of 108 measurements. The mean periotest values and standard deviations were calculated for the master casts and the abutment replicas. The abutment replicas displayed mean periotest values that ranged from +1.3 to -8.0. The study shows that there are significant differences between stable and unstable implant master casts (P = 0.0001, ANOVA-Fisher's protected least significant difference) and abutment replicas (P = 0.0001, Contrast test). The Periotest method will quantify differences in gypsum stone implant master casts as well as the prosthesis supporting brass abutment replicas that are an integral part of the master cast.

Analysis of Variance↗
PubMed1999

In vitro stress analyses of dental implants supporting screw-retained and cement-retained prostheses.

A photoelastic and strain gauge analysis was performed to evaluate the stress transferred to implants through the provisional-cement-retained, the permanent-cement-retained, and the screw-retained prostheses. The deflections of the prostheses at the time of the loading were also measured. In the single crown test, the provisional-cement-retained crowns transferred less stress. In the two-unit fixed partial denture test, there were no differences between the three different prostheses. In the two-implant supported distal cantilevered prostheses, the screw-type and the permanent-cement-retained prostheses developed more stress around the apex of both implants. The permanent-cement-retained prostheses acted almost the same as the screw-type.

Birefringence↗
PubMed1999

Study of the effect of using mini-transitional implants as temporary abutments in implant overdenture cases.

In an attempt to improve patient satisfaction during the healing period after placement of implants, mini-transitional implants (MTIs) have been advocated to allow immediate use of temporary dentures and to prevent transmucosal loads over the definitive implants. Twelve edentulous patients received two screw implants each in the predetermined mandibular canine region. At the time of surgery, six patients had two MTIs placed medially to the permanent ones. The flap was repositioned allowing transmucosal penetration of MTIs. Patients left the operating room wearing their relined lower dentures. The results indicated that MTIs integrated sufficiently in bone, giving successful immediate support for the transitional prosthesis and allowing proper mucosal healing. Two of these transitional implants showed mobility three months after phase I surgery. After loading the final implants, patients who had MTI-supported dentures showed bone loss that was not significantly different from the control group.

Cuspid↗
PubMed1999

A new paradigm for the construction and service of fixed prosthodontics.

Some of the most disheartening things that can happen to restorative dentists is to be faced with problems, complications, and failures in their own fixed prosthodontics. A highly advantageous technique for removing existing restorations and creating removable cement-retained fixed prosthodontics has been described. In the history of crown and bridge prosthodontics, there has not been a proven precision technique to remove these restorations, with the exception of screw-retained implant prostheses, which exhibit many disadvantages. This new paradigm provides a new dimension to the practice of dentistry and allows for the repair, service, and maintenance of restorations in ways that have never been done in the past. Removing crowns and fixed bridges can be learned like any other dental skill, such as endodontics or taking accurate impressions. Skill and confidence comes when the technique has been performed on a large variety of cases. Being able to quickly and easily remove these restorations can certainly be rewarding and reduce a lot of stress.

Dental Prosthesis Retention↗
PubMedDate not supplied

Mechanics of the implant-abutment connection: an 8-degree taper compared to a butt joint connection.

This paper presents aa comparison between the 8-degree Morse Taper and the butt joint aa connections between an implant and an abutment. Three-dimensional, non-linear finite element models were created to compare the 2 connection principles under equal conditions. The loading configuration was thereby modeled according to a test setup actually used for the dynamic long-term testing of dental implants as required for regulatory purposes. The results give insight into the mechanics involved in each type of connection and are compared to actual findings with the testing machine. The comparison indicates the superior mechanics of conical abutment connections and helps to explain their significantly better long-term stability in the clinical application.

Dental Abutments↗