Marginal bone resorption at different treatment concepts using Brånemark dental implants in anterior mandibles.

BACKGROUND: Different implant treatment modalities, one- and two-step surgery, and one-step surgery combined with early functional loading have successfully been used in the anterior mandible for rehabilitation of edentulism. However, the marginal bone remodeling has not been compared among the three different techniques. PURPOSE: The purpose was to compare the marginal bone level in a short- and long-term perspective study using Brånemark dental implants placed according to either a one- or a two-step surgical procedure or a one-step surgical procedure combined with early functional loading. MATERIALS AND METHODS: Seven patients were treated with a split-mouth technique with a one-step surgical technique on one side and a two-step technique on the other side. In this latter group, the fixtures were submerged during a 3- to 4-month healing period before abutment connection and loading. In 13 patients, following one-step surgery, the permanent prosthetic suprastructure was connected within 20 days from implant surgery. All patients were operated on by the same surgeon. The level of the marginal bone was radiographically measured relative to the fixture-abutment junction and was followed up to 5 years from fixture installation. RESULTS: After connection of the supraconstruction, the marginal bone resorption was significantly lower in the early functional loading group compared to the one- and two-step surgical technique groups. However, after 18 months and after 5 years, the marginal bone was located approximately 1 mm apical to the fixture-abutment level in all three groups. CONCLUSION: There was no difference in marginal bone resorption in a long-term perspective between one- and two-step surgical procedures and a one-step surgical procedure with early functional loading of Brånemark dental implants.

Immediate functional loading of Brånemark single tooth implants. An 18 months' clinical pilot follow-up study.

A clinical and radiographical study was performed to evaluate the treatment outcome of single tooth replacements with artificial crowns retained to implants installed according to a 1-stage surgical procedure and immediate loading (Experimental Group = EG) in comparison to the original 2-stage concept (Control Group = CG). The EG comprised 14 patients (= 14 implants) and the CG comprised 8 patients (= 8 implants), all with single tooth losses anterior to the molars. Beyond the non-smoking criterion the following criteria were adopted: i) the amount of bone had to allow for installation of a fixture with a minimum length of 13 mm and Ø = 3.75 mm, ii) the jaw relationship had to allow for bilateral occlusal stability, iii) the patients should be judged to be non-bruxers, and iv) the patients had to be available for the follow-up and maintenance programme. In the EG a temporary crown was connected to the implant within 24 h following fixture installation. Six months later this crown was replaced with a permanent one. In the CG the surgical and prosthetic treatment followed the standard protocol. Out of the 14 fixtures in the EG 2 were lost up to 5 months in function and were subsequently removed. All remaining 12 implants were stable at every subsequent follow-up examination. No fixture losses were recorded in the CG and all implants in this group were stable at the follow-ups. At the 6-month observation interval all the participating 20 patients were radiographically examined, an examination that was repeated at the 18-month follow-up. The analysis of the radiographs from the EG as well as from the CG disclosed that during the 12-month observation period the mean change of bone support was about 0.1 mm. Further studies, designed as controlled multicenter ones, have to be performed before the results of this pilot study can be recommended for more general use.

Early functional loading of Brånemark dental implants: 5-year clinical follow-up study.

BACKGROUND: Short-term clinical studies have indicated the possibility of one-stage surgery and early loading of machined titanium implants. However, long-term data comparing the outcome to the conventional two-stage technique are missing. PURPOSE: A clinical and radiographic study was performed to compare the outcome of oral rehabilitation of the edentulous mandible by fixed suprastructures connected to implants installed according to either (1) a one-stage surgical procedure and early loading (experimental group--EG) or (2) the original two-stage concept (reference group--RG). The EG and RG comprised 16 and 11 subjects, respectively. MATERIALS AND METHODS: The following specific inclusion criterion were adopted: (1) all patients had to consider themselves to be in good general health, (2) the amount of bone had to enable the installation of five to six, at least 10-mm long fixtures (Mk II fixtures; Nobel Biocare AB, Göteborg, Sweden) between the mental foramina, and (3) the patients had to be available for the follow-up and maintenance program. A total of 88 implants were placed in the EG compared to 30 in the RG. In the EG, fixed appliances were connected to the implants within 20 days following implant installation while the fixed appliances in the RG were connected about 4 months following fixture installation. At delivery of the suprastructures, all patients were radiographically examined, an examination that was repeated at the 18- and 60-month follow-ups. RESULTS: The analysis of the radiographs from the EG disclosed that during the observation period, between 18 and 60 months, the mean loss of bone support amounted to 0.2 mm (SD = 0.4). The corresponding value observed in the RG was 0.0 mm (SD = 0.5). During the 60-month observation period, no fixture was lost in any of the two groups examined. The implants under study as well as those in the reference material were at all observation intervals found to be clinically stable. CONCLUSIONS: This clinical study demonstrated that it is, at least based on a 5-year observation period, possible to successfully load via a permanent fixed rigid cross-arch suprastructure titanium dental implants soon after installation. However, such a treatment approach has to be strictly limited to the interforamina area of the edentulous mandible. Furthermore, the bone resorption was found to be within the same range around such implants as around implants installed and loaded according to the original two-stage protocol.

Immediate functional loading of Brånemark dental implants. An 18-month clinical follow-up study.

A clinical and radiographical study was performed to compare the outcome of oral rehabilitation in the edentulous mandible by fixed supraconstructions connected to implants installed according to either i) a 1-stage surgical procedure and immediate loading (Experimental Group-EG), or ii) the original 2-stage concept (Reference Group-RG). The EG comprised 16 subjects with edentulous mandibles. Beyond the non-smoking criteria the following specific inclusion criteria were adopted: i) all patients had to consider themselves to be in good general health, ii) the amount of bone had to enable the installation of 5-6, at least 10 mm long fixtures to be bicortically anchored (Mk II fixtures; Nobel Biocare AB, Göteborg, Sweden) between the mental foramina, and iii) the patients had to be available for the follow-up and maintenance programme. A total of 88 implants were placed in the EG (16 patients) compared to 30 in the RG (11 patients). In the EG, fixed appliances were connected to the implants within 20 days following implant installation while the fixed appliances in the RG were connected about 4 months following fixture installation. At the time for delivery of the supraconstructions all 27 patients were radiographically examined, an examination that was repeated at the 18-month follow-up. The analysis of the radiographs from the EG disclosed that during the 18-month observation period the mean loss of bone support amounted to 0.4 mm. The corresponding value observed in the RG was 0.8 mm. During the 18-month observation period no fixture was lost in any of the 2 groups examined. The implants under study as well as those in the reference material were at all observation intervals found to be clinically stable. The present clinical study demonstrated that it is, at least based on an 18-month observation period, possible to successfully load titanium dental implants immediately following installation via a permanent fixed rigid cross-arch supraconstruction. However, such a treatment approach has so far to be strictly limited to the inter-foramina area of the edentulous mandible.

Some clinical and radiographical features of submerged and non-submerged titanium implants. A 5-year follow-up study.

The present study reports on the results of a follow-up examination of patient material, 5 years after the installation of the fixed supraconstruction. The patient group comprised 11 individuals. Briefly, a split-mouth technique of treatment was used. In the right side of the mandible the traditional 2-step surgical approach for implant installation was used. In the left jaw quadrant a 1-step surgical procedure was used. A clinical and radiographical examination was performed 5 years after the initial connection of the supraconstruction to the implants. At the 5-year follow-up examination all 61 implants examined at the 18-month follow-up were still in service and found to be clinically stable irrespective of the surgical procedure used. Furthermore, the results of the present clinical and radiographical follow-up study demonstrate that the marginal bone level at implants placed anteriorly in the edentulous mandible and supporting fixed supraconstructions is stable between 18 and 60 months irrespective of whether placed according to a 1-step or 2-step surgical procedure.

The influence of the palatal major conccector on the rigidity of a conical crown retained denture.

The influence of the major connector on the rigidity of a maxillary conical crown retained denture was evaluated in vivo. A duplicate maxillary conical crown prosthesis carrying 9 electrical resistance strain gauges was manufactured for one partially dentate male. Clinical loading experiments were performed with the original construction design, after partial and complete removal of the major connector. The results showed that the separation of the major connector caused a general increase in the deformation level, particularly in the anterior region. In conclusion, the palatal major connector was found to increase the rigidity of a maxillary conical crown retained denture.

Clinical and radiographical features of submerged and nonsubmerged titanium implants.

A clinical and radiographical study was performed to evaluate whether initial submergence of titanium fixtures is an obligate treatment measure for the establishment of proper bone anchorage when implants a.m. Brånemark are used. The sample was comprised of 11 subjects with edentulous mandibles. A split-mouth design was employed; in the right mandibular quadrant a traditional 2-step procedure for fixture installation and abutment connection was utilized, while in the left quadrant a 1-step procedure was carried out, i.e., fixtures were placed and abutments were connected in one and the same session. Three to 4 months after fixture installation, fixed bridgeworks were fabricated and rigidly connected to the implants. Clinical examinations (including probing pocket depth, bleeding on probing and implant stability test) were performed after 12 and 18 months. Radiographs were taken following insertion of the bridges and at the 12- and 18-month re-examinations. The probing pocket depth, the bleeding on probing, the implant stability and the radiographic determinations were similar for the 2 groups of treatment alternatives. This indicates that titanium fixtures a.m. Brånemark can be properly anchored (osseointegrated) in mandibular bone and successfully used for bridge retention also when a 1-step procedure is used for implant installation.

On functional strain in fixed and removable partial dentures. An experimental in vivo study.

Three rosette strain gauges were attached to a fixed bilateral cantilevered crossarch maxillary bridge and one linear strain gauge to an attachment-retained removable partial denture (RPD), to study the functional deformation pattern in this combined reconstruction. The deformation under clinical conditions at maximum habitual biting and at maximum unilateral loading was very complex, with both elongation and contraction in different parts of the fixed reconstruction. Even though this complexity in the functional deformation was found both with and without the RPD incorporated, the RPD seemed to provide a more even and favorable distribution of the masticatory forces in the fixed reconstruction.

On clinical loading of osseointegrated implants. A methodological and clinical study.

Strain gauges were used to record in vivo and in vitro functional deformations in a fixed prosthetic appliance supported and retained by osseointegrated titanium implants. Four linear gauges were attached to each of totally 5 implant abutment cylinders and gauge signals were transferred into a computer via a digital converter. A computer program (ASYST) was used for collection, calibration and analysis of data obtained. Based on the results of a series of explorative in vitro tests, in vivo experiments were performed at maximum biting as well as during chewing on certain normally available food items. The results show fundamental differences between in vitro and in vivo testing conditions. Unexpectedly high bending of the implants was recorded in many of the in vivo loading situations.

On functional strain in some fixed and removable partial dentures. An experimental in vitro study.

An 11-unit fixed maxillary reconstruction with 2 bilateral cantilever pontics in combination with a removable partial denture (RPD) with a palatal bar was fabricated. The RPD was retained to the fixed reconstruction with precision attachments. A laboratory model system was constructed in such a manner that the mechanical properties of the biologic supporting tissues involved were simulated by artificial materials. By means of a strain-gauge technique the deformation was studied in both the fixed and the removable partial denture. In different laboratory loading situations with and without the RPD the deformation in the fixed dental appliance was more extensive and more complex when the RPD was excluded.

Influence of low-viscosity liners on the retention of three luting materials.

A number of materials are available to protect the pulp from postoperative sensitivity. The effect of a calcium hydroxide liner and a dentinal desensitizing agent (potassium oxalate) on crown retention was investigated. Gold crowns were cemented on standardized crown preparations with zinc phosphate cement, glass-ionomer cement, or one of two resin cements. A tensile force was applied until separation occurred. The mean applied force at rupture varied greatly among the groups, indicating that the pulpal protection agent may have a distinct effect on the retention of cast restorations. In addition, other clinical factors, such as angle of convergence, crown height, and total surface area of the tooth should be considered.

On the clinical deformation of maxillary complete dentures. Influence of denture-base design and shape of denture-bearing tissue.

This paper aimed to study the influence of denture base design and the shape of the denture-supporting area on the functional deformation of maxillary complete dentures. Six strain-gauged duplicate maxillary dentures were made for the study of two test subjects with different shapes of the palatal vault. Each subject was supplied with two polymethyl methacrylate dentures, one with a 1-mm-thick palatal base and the other 2 mm thick. A third denture was constructed with a cobalt-chromium base. The functional loading tests included maximum biting and the chewing of the food test samples. An analysis based on chewing time and total number of chewing cycles per test piece was also made. The results showed that surface straining is highly complex at the anterior part of the maxillary dentures constructed from polymethyl methacrylate and that increasing the denture thickness per se might not be accompanied by a reduction of strain. The results also suggest that high thrust to the supporting tissue is produced with high palatal vault dentures made in polymethyl methacrylate. The study proposes that cobalt-chromium bases may be used in maxillary dentures to reduce functional deformation and thrust to the supporting tissues at the anterior part of the maxilla.

On the clinical deformation of maxillary complete dentures. Influence of the processing techniques of acrylate-based polymers.

This paper aims to study the functional deformation patterns of complete maxillary dentures constructed in three different types of denture base materials and with two techniques of processing of dentures. The patients' evaluation of the fit of the dentures was also recorded. Thirty strain-gauged duplicate dentures were made for this study of five test subjects. The functional loading tests included maximum biting and the chewing of three food test samples. The results showed that there was no correlation between the patients' evaluation and acceptance of the fit of the dentures and the actual straining magnitudes and deformation of their dentures. The results also suggest that dentures manufactured from toughened or co-polymerized poly(methyl methacrylate) and processed by the injection molding technique deform to a lesser extent than when processed by by the compression molding technique. Standard poly(methyl methacrylate) seems to be less sensitive to the processing technique.

On cantilever loading of vital and non-vital teeth. An experimental clinical study.

Three healthy subjects with neighboring or contralateral vital and root-filled teeth requiring crown therapy were selected as test persons. All teeth had optimal alveolar bone support. The root-filled teeth were furnished with individual cast posts and cores, and veneer crowns were made on both the vital and non-vital teeth. Buccal extension bars were then soldered to the occlusal surfaces of these crowns, and weights were applied in different positions along the bars until the test persons experienced pain. The experiments were repeated under local anesthesia. The results showed that non-vital teeth had mean pain threshold levels that, on cantilever loading, were more than twice as high as those of their neighboring or contralateral vital teeth. The positions of the centers of rotational deformations of the loaded teeth, which were assumed to be mainly rotational, were calculated and found to be located inside the peripheries of the crowns for the vital teeth but extracoronally in markedly more peripheral positions for the non-vital teeth.

Technical failures and some related clinical complications in extensive fixed prosthodontics. An epidemiological study of long-term clinical quality.

Three hundred and sixteen fixed partial dentures made in 1975-1976 by 112 general practitioners in Malmö, Sweden, were selected for a questionnaire study of the technical failure rates after 6-7 years. Cariologic, periodontal, endodontic, and esthetic complications were also identified, as were those appearing in the stomatognathic system. The total material consisted of three groups with an approximately equal number of reconstructions. One group consisted of fixed partial dentures with distal abutment teeth, another was formed of fixed prostheses with single cantilever pontic/pontics, and a third consisted of double cantilever pontics. Excluding the 26 reconstructions, which had been made for patients who died (24) or emigrated (2) during the observation period, data was obtained for 97% of the selected restorations. The results showed high rates of cariologic (18-31%), endodontic (5-23%), periodontal (7-12%), esthetic (10-16%), and technical (8-34%) complications. Differences were noted between the groups. For all types of technical failures (fractures and loss of retention) higher frequencies were related to the extent of cantilevering. Direct relationships were found between the technical failure rate and the time in service, the sum of all cantilever extension pontics in the reconstructions, and the state of the pulps of the distal abutments. No relationship was found between the technical failure rate and the status of the dentition in the opposing jaw. The clinical significance of the results obtained is discussed.

On functional strain in fixed mandibular reconstructions. II. An in vivo study.

Six linear strain gauges and one rosette strain gauge were used on one partially dentate subject to study various types of functional deformation in a six-unit conventionally designed fixed mandibular bridge and a five-unit cantilever fixed mandibular bridge. The results of this study show that the clinical straining pattern was complex and different from those recorded in laboratory model studies of the same case. It was therefore concluded that functional deformations of fixed dental appliances can be studied accurately only in clinical experiments. Fundamentally different straining patterns were observed between the conventionally designed bridge and the cantilever one. The clinical significance of these results are discussed in relation to prosthetic treatment with various types of fixed-bridge constructions.

On functional strain in fixed mandibular reconstructions. I. An in vitro study.

Six linear strain gauges and one rosette strain gauge were used on three different types of models prepared from one partially dentate subject, to study loading deformation in a six-unit fixed mandibular bridge. The bridge was mounted on each of the models on an adjustable articulator and loaded in a universal testing machine at loading levels ranging from 0 to 491 N. The results showed considerable differences between the three types of model, with regard to both the magnitude of the recorded strains for the individual gauges and the calculated direction of the principal strains under the rosette gauges. The findings indicate that the mechanical properties and the design of the supporting structures have a major influence on the functional deformation of fixed dental appliances.