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PubMed2002

Evaluation of stability of titanium and hydroxyapatite-coated osseointegrated dental implants: a pilot study.

An endosseous implant is described as osseointegrated when it is immobile in function. Objective measures of stability testing have been described. The Periotest is a commercially available device that is used for this purpose. This study was designed to measure stability of endosseous implants placed in the mandible. Implants were placed in the mandibular canine or first premolar area to support an overdenture prosthesis. Stability was evaluated through the use of a Periotest device at the time of implant placement and following one year of functional loading. Implant designs were either a screw-shaped titanium alloy or a hydroxyapatite-coated cylinder. A total of 54 implants were placed, 37 were titanium screw-shaped implants, while the remaining 17 were hydroxyapatite cylinders. Initial measurements of stability showed no difference due to implant type. Following one year of functional loading, titanium screw-shaped implants were more stable than hydroxyapatite implants (P < 0.05). The difference in implant rigidity following a period of functional loading may be an indication of a difference in osseointegration between the two implants used in this study.

Aged↗
PubMed2003

Brånemark and ITI dental implants in the human bone-grafted maxilla: a comparative evaluation.

The development of new characteristics concerning implant surface makes it interesting to clinically compare different implant systems in the bone-grafted maxilla. The aim of this evaluation was to compare clinical data of a two-staged procedure on the augmented extremely atrophic maxilla using either Brånemark- or ITI-fixures. In 25 patients (18 females, seven males) the severely atrophied maxilla was reconstructed with autogenous iliac or mandibular bone and either Brånemark or ITI implants. Seventy-eight Brånemark implants and 80 SLA-ITI implants were inserted in the augmented bone and the patients were followed between 20 and 67 months post implantation. The bone graft was transplanted to add bony volume in the maxillary sinus, the anterior floor of the nose and/or the alveolar ridge. After a healing period of 4(1/2) months, dental implants were inserted and left for healing for 8 months. Twelve consecutive patients received machine-surfaced Brånemark fixtures and 13 consecutive patients received SLA-ITI fixtures. Gradual loading was applied after healing abutment application. After 6 months the permanent prosthetic reconstruction was provided to the patient, either as a fixed or removable bridge. Comparison in survival rate was performed: 15 machined Brånemark fixtures were lost, resulting in an overall survival rate of 81%. Two ITI fixtures were lost, resulting in an overall survival rate of 98%. The results of this evaluation show that sandblasted large grit acid etched surface-treated ITI implants has a significant higher survival rate than machine-surfaced Brånemark implants in autogenous grafted maxillary bone.

Adult↗
PubMed2002

Two-part implants inserted in a one-stage or a two-stage procedure. A prospective comparative study.

OBJECTIVE: The aim of this study was to evaluate the feasibility of using a two-part implant system in a one-stage procedure and to monitor the microflora in the peri-implant area in relation to clinical and radiographic outcome. MATERIAL AND METHODS: After randomisation, 40 edentulous patients (Cawood & Howell class V-VI) received two IMZ implants in the anterior mandible inserted by either a one-stage (n = 20) or a two-stage (n = 20) surgical procedure for overdenture treatment. A standardised clinical and radiographic evaluation was performed after denture insertion as well as 6 and 12 months thereafter. Twelve months after loading, peri-implant samples were collected and analysed for the presence of putative periodontal pathogens using culture technique. RESULTS: No striking differences were found between the two groups with regard to the clinical parameters during the evaluation period. The mean bone loss in the first year of functioning was 0.6 mm in both groups. With regard to the gingiva score, plaque score, bleeding score or bone loss between T0 and T12, no associations were found with the presence of the cultured microorganisms. An association was present between pockets >or= 4 mm and the presence of Peptostreptococcus micros in the two-stage group. CONCLUSIONS: The short-term results indicate that two-part implants inserted in a one-stage procedure may be as predictable as inserted in the common two-stage procedure. The peri-implant sulcus can and does harbour potential periodontal pathogens without significant signs of tissue breakdown.

Colony Count, Microbial↗
PubMed2002

Good occlusal practice in the provision of implant borne prostheses.

The increased use of endosseous dental implants means that many dentists will encounter patients with dental implants in their everyday practice. Dental practitioners might be actively involved in the provision of implant borne prostheses at both the surgical and restorative phases, or only at the restorative stage. This section is written for all dentists and aims to examine the subject of occlusion within implantology. It aims to provide guidelines of good occlusal practice to be used in the design of the prosthesis that is supported or retained by one or more implants. As implantology is a 'new' discipline of dentistry, there are fewer standard texts and this section, therefore, is much more extensively referenced than the subjects that have been considered to date.

Centric Relation↗
PubMed1996

Follow up and maintenance of implant supported prostheses: a comparison of 20 complete mandibular overdentures and 20 complete mandibular fixed cantilever prostheses.

Two independently selected groups of 20 patients who were edentulous in te mandible, were followed up on a regular basis over a 5-year period following restoration with a lower implant stabilised prosthesis and conventional upper denture. Significantly more treatment was required by those who received complete mandibular overdentures than those provided with complete fixed mandibular prostheses. In addition to adjustment for the relief of denture trauma to the mucosa, more mechanical problems arose with overdenture implant prostheses.

Dental Abutments↗
PubMed2003

Early loading of endosseous implants in the augmented maxilla: a 1-year prospective study.

In 10 patients, 68 endosseous implants were inserted in the augmented edentulous maxilla using a one-stage implant placement technique. Three months before implant insertion, the width and height of the alveolar crest were augmented with autologous bone grafts from the iliac crest. In all cases, the resulting bone volume was sufficient for implant insertion. According to an early loading protocol, the implant-supported overdenture was fabricated 2 months after insertion of the implants. Evaluation was performed according to a standardised protocol immediately and 1 year after fabrication of the prosthetic construction. The protocol included assessment of both clinical (bleeding score, pocket depth, implant mobility) and radiographic (marginal bone level on standardised radiographs) parameters. Three implants in two patients in the upper jaw were lost (survival rate: 95.6%). The peri-implant tissues had a healthy appearance and bone loss was minimal. Overall, the patients were very satisfied with the prosthetic construction. From this preliminary study, it is concluded that in selected cases, early loading of implants may develop into a predictable treatment modality after augmentation of the maxilla.

Adult↗
PubMed2003

Simultaneous or staged installation with guided bone augmentation of transmucosal titanium implants. A 3-year prospective cohort study.

A prospective cohort study of 45 nonsmoking consecutively admitted patients was studied for the treatment outcomes following jaw bone augmentation in conjunction with installment of oral implants. Twenty-eight patients were treated for both bone augmentation and implant treatment simultaneously, while 17 patients were treated with a staged approach with the bone augmentation being performed 6-8 months prior to implant installation. Three months following this, prosthetic reconstructions were incorporated. One year thereafter, baseline data and 3 years after reconstruction, follow-up data were obtained. Moderately low mean scores for the bleeding on probing percentage were found at baseline (24%) and after 3 years of function (17%), while the corresponding values at the implant sites were 40.6% and 52.4%, respectively. However, the modified gingival index (mGI) = 2 was found in only 4.8%, and 6.9% at the baseline and 3-year examinations. Peri-implant Probing depth (PPD) and level of attachment mean values did not vary between baseline and follow-up examinations. Only a small proportion of 1.8% yielded PPD = 6.0 mm after 3 years of function. Radiographic bone level measurements showed that 18.2% of the implants lost 0.5 mm during the observation period. Seventy percent of the sites were considered completely stable. It was concluded that predictable treatment outcomes resulted for oral implant installation combined with or staged after jawbone augmentation. Only 6.5% of the sites had lost 1.5% crestal bone with the staged approach while 14% of the sites had lost 1.5 mm, when the implants were placed simultaneously. This suggests that the staged approach may have a lower risk for greater amounts of crestal bone loss as the simultaneous approach. In general, crestal bone loss encountered in the present study corresponded very well with that reported following placement of the same implant system into nonaugmented bone.

Alveolar Bone Loss↗
PubMed1996

An in vivo quantitative analysis of the fit of Nobel Biocare implant superstructures.

Loss of osseointegration of implant fixtures and mechanical failure of superstructures have been attributed to failure to achieve a passive fit between the superstructure and the transmucosal abutment (TMA). The fit of five mandibular superstructures, fabricated on Nobel Biocare implants, was investigated in vivo, using a polyvinyl siloxane impression material to record the discrepancies. Following sectioning of the impressions, the vertical and horizontal discrepancies were analysed at four locations using a travelling microscope. The discrepancies obtained were measured both when the gold cylinder screws were maximally tightened by hand and when tightened with a torque driver to the recommended value of 10 Ncm. The vertical discrepancies for the hand tightened abutments ranged from 0 micron to 63 microns with a mean of 14 microns. In the mechanically tightened group, the vertical discrepancies ranged from 0 micron to 130 microns with a mean of 21 microns. The horizontal discrepancies for the mechanically tightened abutments ranged from 0 micron to 140 microns with a mean of 31 microns, compared with a mean of 46 microns and range of 0 micron to 113 microns, for the hand-tightened abutments. A close fit was seldom achieved. It is concluded that considerable discrepancies existed around superstructures that had been judged to have a clinically acceptable fit. These were reduced in the vertical direction by hand tightening of the gold screws.

Dental Abutments↗
PubMed2000

Comparison of the transfer precision of three different impression materials in combination with transfer caps for the Frialit-2 system.

Transfer of the precise position of implants to a master cast is a prerequisite for accurate and passive fit of the superstructure. Implants lack the mobility of natural teeth and, therefore, inaccurate frameworks result in stress within the mechanical parts and the implant-bone interface. Various impression methods have been described to achieve accurate reproduction of the intra-oral relation of the implants. The aim of this experimental study was to compare three different impression materials (polyether, polyvinyl siloxane, hydrocolloid) with the Frialit(R)-2 system and with the indirect technique. In addition, the use of transfer caps (TCs) to improve transfer precision was tested with all three materials. All measurements were performed using a three-dimensional (3D) co-ordinate measuring machine that is capable of locating points in space and calculating the relative distortions as angles of tilt (rot-XY, rot-XZ, rot-YZ) and 3D displacement. The results suggest that addition-silicone (a-silicone) and polyether are the materials of choice for implant transfer procedures. The use of TCs resulted in a significantly reduced rotation in the XY-plane but did not improve the absolute 3D displacement. A-silicone with the use of TCs proved to be most precise. Comparison between polyether and polyvinyl siloxane showed significant differences in the XY-rotation and the 3D displacement in favour of the silicone. Because the mean distortions between the original model and the master casts were about 100 microm, absolutely precise fit may be unattainable owing to the physical properties of the materials. Further studies will have to evaluate the amount of tolerable stress at the implant-bone interface.

Alginates↗
PubMed2001

Glass-fibre-reinforced-composite fixed partial dentures on dental implants.

UNLABELLED: The objective was to investigate the fracture strength and marginal fit of implant suprastructures made of fibre-reinforced composite which were fixed onto the implants using cementation or screws. A sample (n=8) of 4-unit bridges, made of the fibre-reinforced composite Vectris/Targis, were adhesively cemented onto titanium conical implant abutments. The second sample consisted of eight screwable Vectris/Targis bridges which were based on prototypes of titanium crown bases. After a 5 year simulation of thermal cycling and mechanical loading (TCML), all specimen were loaded to fracture. Marginal fit was investigated using a semiquantitative SEM analysis. The cemented 4-unit bridges showed a fracture strength of 1553 N (Q1=1498 N, Q3=1825 N) and the screw-fixed bridges had a median of 1457 N (Q1=1223 N, Q3= 1781 N). The analysis of the marginal adaptation showed similar results of cemented and screwed bridges. The bond between the Targis facing-material and the composite cement was significantly deteriorated after TCML. CONCLUSION: Suprastructures made of glass-fibre-reinforced composite could become an alternative to reconstructions with a metal-framework. Both, fixation onto the implants with screws or cementation, are possible.

Composite Resins↗
PubMed2002

Five years of aftercare of implant-retained mandibular overdentures and conventional dentures.

The purpose of this multicentre randomized clinical trial was to analyse surgical and prosthetic aftercare and clinical implant performance of edentulous patients with implant-retained mandibular overdentures and of patients with conventional dentures, either or not after pre-prosthetic vestibuloplasty and deepening of the floor of the mouth. The evaluation period was 5 years. The implant systems evaluated were the IMZ implant system, the Brånemark implant system and the Transmandibular Implant system. The centre in Groningen had five groups (n=149) and the centre in Nijmegen had three groups (n=86). The evaluation comprised of surgical and prosthetic aftercare, together with clinical implant performance (CIP). The highest implant loss (29%) is found in the Transmandibular Implant group. All groups had prosthetic revisions and complications according to the CIP-scale. The majority of the patients in the endosseous implant groups were subject to minor complications. The CIP-score of the Transmandibular Implant group is significantly higher than the scores of the other groups, because of the high number of lost posts. In 26;1% of the patients in this group score 4 is given, which means failure of the implant system. From this study it can be concluded that the endosseous implant systems used in this study have less surgical aftercare and a better clinical implant performance than the Transmandibular Implant system and are therefore the systems of choice for the edentulous mandible.

Aftercare↗
PubMed2002

The influence of the location of load transfer on strains around implants supporting four unit cement-retained fixed prostheses: in vitro evaluation of axial versus off-set loading.

Prudent control of the biomechanical load on dental implants is imperative to achieve long-term clinical success. The design of the final prosthesis and location of force transmission have a definitive influence on the quantification of induced strains and load partitioning among implants. While axial loading of implants generate an even distribution of stresses in the bone around implants, off-set loading, which is particularly observed in screw retained prosthesis increases the stresses at the bone-implant interface. This study evaluated the cervical strains on dental implants supporting four unit cement retained fixed prostheses under 50 N static axial and off-set loading conditions. As the type of strains are also dependent on the point of load transfer, design of the prosthesis and implant positioning, the study comprised the evaluation of induced strains through a simulation of five cement retained prosthetic options. The results revealed that off-set loading increases the magnitude of strains. However, it was not significant for all configurations (P < 0.05). This finding emphasizes the accompanying effect of implant location, angulation and macrogeometry of the prosthesis and, that the biomechanical evaluation of affecting factors is a multifaceted phenomenon.

Analysis of Variance↗
PubMed2001

Implant-retained mandibular overdentures: 6-year results of a multicenter clinical trial on 3 different implant systems.

PURPOSE: The goal of this multicenter prospective clinical trial was to compare clinical outcome and post-treatment care and patient satisfaction with different implant systems used for mandibular overdenture treatment during a 6-year follow-up period. PATIENTS AND METHODS: A total of 87 edentulous patients with a severely resorbed mandible (bone height, 8 to 15 mm) received treatment involving either 2 Intra Mobiele Zylinder implants (IMZ group, n = 41) (Friedrichsfeld AG, Mannheim, Germany), 2 Brånemark implants (Brå group, n = 17) (Nobel Biocare AB, Gothenburg, Sweden) or a Transmandibular Implant (TMI; Krijnen Medical, Beesd, The Netherlands) (TMI group, n = 29). The evaluation involved clinical parameters, radiographs, surgical and prosthetic post-treatment care, clinical implant performance (CIP scale), and patient satisfaction. RESULTS: After 6 years, there was a significant difference in the mean plaque index:the mean plaque index of the TMI group was significantly higher than that of the IMZ and Brå groups. Other clinical parameters showed no significant differences. The implant survival rate of 97.5% was noted in the IMZ group, 97.1% in the Brå group, and 72.0% in the TMI group. The CIP scale were significantly worse for the TMI group. CONCLUSION: It was concluded that the IMZ and the Brånemark implant systems have a better survival rate and clinical implant performance than the TMI system. Based on these data, these systems should be the choice for the edentulous mandible with a height between 8 and 15 mm.

Alveolar Bone Loss↗
PubMed2002

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone.

PURPOSE: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. PATIENTS AND METHODS: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. RESULTS: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. CONCLUSIONS: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption.

Aged↗
PubMed2003

Survival rate of IMZ implants: a prospective 10-year analysis.

PURPOSE: The purpose of this study was to determine the success of IMZ implants after prosthodontic rehabilitation. PATIENTS AND METHODS: A prospective study analysis was made of the treatment results for 541 patients after the insertion of a total of 1,250 IMZ implants at 2 practicing dentists' offices over a period of 13 years. The most frequent treatment situations were insertion in the totally edentulous lower jaw (44.1%) and in a distal edentulous region (37.6%). The statistical survival rate assessment was made using Kaplan-Meier survival analysis. The results were compared with the cumulative survival rates for all implants during a period of 10 years. RESULTS: At 5 years after insertion, 96.0% of all implants were in situ and noninflamed; after 10 years, the survival rate was 82.4%. For both the upper and the lower jaw, better results were recorded in the posterior part of the jaw than in the anterior part. CONCLUSIONS: The IMZ implant system showed a good 10-year-survival rate.

Adult↗
PubMed2000

Effect of anchorage systems and extension base contact on load transfer with mandibular implant-retained overdentures.

STATEMENT OF PROBLEM: Controversy exists regarding the effect of anchorage systems and extension base contact on stress transfer to multiple implants by mandibular overdentures. PURPOSE: This simulation study measured photoelastically the biologic behavior of 4 implants retaining a mandibular overdenture. The purpose of the investigation was to compare the load transfer characteristics of different mandibular-retained overdenture designs, with and without edentulous ridge contact. MATERIAL AND METHODS: A photoelastic model of a human edentulous mandible was fabricated having 4 screw-type implants (3.75 x 10 mm) embedded in the parasymphyseal area. Substructure designs utilizing a cantilevered bar, spark erosion framework, noncantilevered bar, and solitary anchors were fabricated. A vertical load of 30 lb was applied to the first molar unilaterally on each of the 4 standardized overdenture prostheses, with and without a silicone tissue spacer, for a total of 8 tested conditions. Stresses that developed in the supporting structure were monitored photoelastically and recorded photographically. RESULTS: Without the simulated tissue contact on the posterior edentulous ridge, the cantilevered bar framework caused the highest stresses to the terminal implant, followed by spark erosion framework, non-cantilevered bar, and solitary anchor design. With simulated tissue contact under the extension base, stress transfer to the distal implant was uniformly reduced to a low level. CONCLUSION: Without intimate extension base contact with the posterior edentulous ridge, the cantilevered anchorage systems generated the highest stresses, under load, to the ipsilateral terminal implant and the solitary anchor design transferred the least. With simulated intimate extension base contact, all anchorage systems transferred low stress to the distal implant region. For all conditions and designs, low stress was transferred to the contralateral side of the arch.

Alveolar Process↗
PubMed2002

Peri-implant tissue response of immediately loaded, threaded, HA-coated implants: 1-year results.

STATEMENT OF PROBLEM: Although high success rates have been reported with immediately loaded implants, the peri-implant tissue response has not been well documented. PURPOSE: This study evaluated implant success and peri-implant tissue response of immediately loaded, threaded, hydroxyapatite (HA)-coated root-form implants supporting mandibular bar overdentures with opposing conventional maxillary complete dentures in humans. MATERIAL AND METHODS: Five patients (3 men, 2 women; mean age 61 years) each received 4 HA-coated endosseous root-form implants in the interforaminal region in the mandible. The implants were rigidly splinted with a metal framework within 24 hours. The final EDS clip prosthesis was placed 1 to 2 weeks thereafter. The implants and peri-implant tissues were evaluated clinically and radiographically 0, 1, 3, 6, and 12 months after prosthesis placement. Data were analyzed with a repeated measures 1-way analysis of variance (P<.05). RESULTS: All implants were stable at the end of the observation period (mean Periotest value = -5.9 +/- 1.4). No peri-implant radiolucencies were noted, and no implants were lost. The mean marginal bone changes were -0.42 plus minus 0.34, -0.84 +/- 0.55, -1.14 +/- 0.80, and -1.16 +/- 0.89 mm at the 1-, 3-, 6-, and 12-month follow-ups, respectively (P<.001). Significant declines in the rates of marginal bone changes at each time interval were noted (P<.001). In addition, there were significant decreases in probing depth (P<.001) and plaque index (P<.001) but no significant difference in the frequency of bleeding upon probing (P=.64). CONCLUSION: Within the limitations of this study, the peri-implant tissue response of immediately loaded, HA-coated implants was favorable and comparable to that of conventional, delayed-loaded implants after 1 year.

Aged↗