Damping characteristics of bone‐to‐implant interface; A clinical study with the Periotest® device.

The Periotest® device was used to evaluate the damping characteristics of different bone‐to‐implant interfaces of Brånemark implants. Implant and abutment lengths were found to have a significant influence on Periotest value (PTV). There was no statistical difference between PTVs of implants located in the anterior and posterior areas of the same jaw at abutment connection. No differences were found between PTVs of standard and self‐tapping implants. PTVs at abutment connection were highly influenced by the bone quality. The contact with two corticals, one at each extremity of the implant, was of a greater influence in the maxillary than in the mandibular jaw, indicating a firmer anchorage between the bicortical implants and the surrounding bone. A proaressive decrease of PTVs over time was observed, significant up to 5 years of loading.     

Peri‐implant mucosal aspects of ITI implants supporting overdentures. A five‐year longitudinal study.

Sixty‐six ITI implants placed in the mandible of 33 edentulous elderly patients (mean age: 69 years) were observed longitudinally for 5 years. The implants served as overdenture anchorage either by means of a connecting bar or single spherical attachments. During the study period, 2 implants failed (one because of a peri‐implant lesion and one because of a fracture) and had to be removed. At the beginning of the study, all implants were osseointegrated and had successfully been in function for 335 months. Oral hygiene practices and the peri‐implant mucosal status were assessed according to the criteria of conventional periodontal parameters. Approximately 50% of the implants had been installed into lining mucosa and hence were to surrounded by keratinized mucosa. The peri‐implant mucosal tissue was maintained healthy during the whole observation period, and no or only minimal loss of attachment was observed. The probing depths averaged approximately 3 mm. At the end of the study, orthopantomographic radiographs were obtained from all patients to assess the peri‐implant bony structures. Small local angular bony defects were detected on 16 implants (22%) in 12 patients. Slightly increased probing depths were observed when angular bony defects were present. Loss of attachment was significantly less frequent when the implants had been placed following a prolonged period of edentulousness (<5 years). This study demonstrated that advanced age, reduced dexterity of elderly patients and environmental conditions of overdentures do not represent a 1 higher risk for the development of peri‐implant lesions.     

Non‐submerged implants in the treatment of the edentulous lower jaw. A 2‐year longitudinal study.

Non‐submerged ITI Bonefit implants ITI Dental Implant System) were inserted in edentulous lower jaws of 46 patients. The patients were provided with either a fixed prosthesis or an overdenture, and has been followed during a 2‐year‐period. At the 1‐year examination, the suprastructures were removed permitting test of the individual implant stability. Radiographic examinations were performed in connection with the loading of the implants and at the 1‐year examination. In total 216 implants were inserted. 4 implants were lost before loading and 4 during the 2nd year of function, which gives a survival rate after 1 year of 98% and after 2 years of 96%. The mean marginal bone loss during the first year of function was 0.1mm. However, the marginal bone changes had a high degree of variation and four implants showed a severe bone loss. The intention is to follow this patient group with annual examinations during 5 years.     

Short‐ and long‐term animal studies with a plasma‐sprayed calcium phosphate‐coated implant

A commercially available hydroxyapatite(HA)‐coating was investigated in a 4‐ and 24‐week animal study. HA‐coated and uncoated commercially pure (c.p.) titanium threaded implants were inserted in rabbit tibia and femur. Qualitative histology showed giant cells and macrophages around both types of implants. Histomorphometry demonstrated significantly more bone in contact to the HA‐coated specimens at both follow‐up periods. In contrast, bone area measurements (the amount of bone inside and/or outside the threads) revealed significantly higher percentages of bone around the uncoated c.p. titanium controls after 6 months of follow‐up. The inferior amount of bone around the HA‐coated implants in the longer‐term perspective may relate to macrophage‐induced resorption.     

Use of 5‐mm‐diameter implants: Periotest® values related to a clinical and radiographic evaluation

A modified design of the original Brånemark implant consisting of a cp. Titanium 5.0‐mm‐diameter self‐tapping implant threaded up to the marginal platform has been proposed for specific indications. From February 1992 to November 1995, a total of 185 machined screw implants (Nobel Biocare, Gothenburg, Sweden) were installed in 45 patients to withstand 58 prostheses. Of these, 91 were 3.75mm diameter and 94 were 5.0mm wide. Most of the implants were placed in type B and C bone quantity and type 2 and 3 bone quality. A retrospective evaluation with regard to indications, marginal bone remodelling, Periotest® values (ID) and survival rate is presented. PTv and radiographic measurements were made at abutment connection and repeated 3, 6 and 12 months later and thereafter every year. The follow‐up ranged from 16 to 55 months (mean 32.9 months) post‐loading. Three patients with 8 5.0mm implants dropped‐out of the study at different stages. Out of the wide implants, 1 was expelled during the healing period; 3 were found mobile at the abutment connection; 1 lost its osseointegration suddenly after 2 years of function; 4 belonging to 1 patient did not meet the success criteria due to continuous marginal bone loss. The cumulative success rate of 5.0mm implants (CSR) after 1 year of function was 97.2% for upper jaws and 88.4% in mandibles, whereas the CSR in maxilla after 48 months was 97.2% and 83.4% in mandibles. The obtained PTv from 5.0mm‐wide fixtures in maxilla and mandibles were respectively 1.1 and 0.6 units lower than those obtained PTv for 3.75mm‐diameter implants in the same patients. The hypothesis that there are differences in the damping capacity of the bone surrounding a 5.0mm‐wide implant compared to the 3.75mm‐diameter implant is supported by the PTv results.     

Bone healing capacity of titanium plasma‐sprayed and hydroxylapatite‐coated oral implants

The influence of surface quality, in particular surface topography and implant material, was evaluated by inserting titanium‐ and hydroxylapatite plasma‐sprayed coated implants into the maxilla of 10 goats. Three types of plasma‐spray coatings were applied to tapered, screw shaped implants; titanium plasma‐spray coating (TPS), titanium plasma‐spray coating with additional acid passivation (TPSA) and a bilayered coating (TPS/HA) consisting of titanium plasma‐spray coating (TPS) and a hydroxylapatite part (HA). In addition, as machined implants (TIM) were used as control. A total of 40 implants were inserted according a balanced split plot design. At the end of a 3‐month healing period, it appeared that 5 implants (2 TPS, 1 TPSA, 1 TPS/HA and 1 TiM) were lost. Histological examination revealed a stronger bone response to TPS/HA coated implants. Even the TPS/HA coated implants induced bone formation on the part of the implant inserted into the sinus. No signs of delamination of the TPS coatings were visible. The HA part of the dual coating showed signs of degradation. Histomorphometrical analysis confirmed these findings. A significant difference in bone contact ( P <0.05) was measured between the TPS/HA coated implants and the other types of implants. Linear regression ( r >0.2) showed no correlation between the inscrew values at the base line and the bone contact measurements 3 months after healing. On the basis of these results, we can conclude that the chemical composition of the HA coating has a positive influence on the bone reaction. The influence of roughness is less evident.     

Endosseous titanium implants during and after orthodontic load ‐ an experimental study in the dog

An experiment was carried out to determine whether endosseous titanium implants (Brånemarks®) retain their clinical stability throughout a 26‐week period of continuously applied force (2 N) and what kind of marginal peri‐implant bone changes occur in the process. For this purpose 6 premolars (P3: mandible/maxilla and P4: mandible) were extracted from each of 2 foxhounds, and 12 implants (6 per dog) were positioned in the edentulous maxillary and mandibular areas after the alveolar healing period. Following a 25‐week implant healing period, 8 fixtures (P3 areas) were used as anchoring elements for distalization of the 2nd premolars over a period of 26 weeks: 4 implants served as a control group (P4areas of the mandible). There were no clinical or histological signs of implant dislocation after the load application period. In the presence of mild peri‐implant gingivitis, no increase was found in the incidence of marginal bone resorption adjacent to the loaded implants compared with the non‐loaded implants. In the absence of marginal resorption, subperiosteal bone apposition was detected especially around the test implants in the mandible. This suggests that endosseous titanium implants are suitable as anchoring units for longer‐term orthodontic tooth movements. The applied force may moreover induce marginal bone appositions adjacent I to the implants.     

Comparison of Brånemark fixture integration and short‐term survival using one‐stage or two‐stage surgery in completely and partially edentulous mandibles

The aim of this prospective study was to compare the clinical integration and survival of Brånemark fixtures when using the conventional 2‐stage surgical procedure to a 1‐stage surgical approach in completely and partially edentulous mandibles. A total of 85 patients were consecutively treated for partial ( n =35) or complete ( n =50) mandibular edentulousness. Fixtures removed because of mobility, pain or infection were counted as failures. The first 10 patients of each group were selected for radiographical analysis of crestal bone changes 1 year after prosthesis insertion. In 33 patients with edentulous mandibles, 170 fixtures were placed in a 1‐stage approach. In this group, 4 fixtures (2.4%) were lost prior to prosthetic restoration. Seventeen edentulous patients received a total of 70 fixtures in a 2‐stage procedure. Out of these, 5 fixtures (7.1%) were lost at abutment connection. In 17 partially edentulous patients, 41 fixtures were inserted in a 1‐stage approach. Two fixtures (5%) were lost in this group. Finally, 18 partially edentulous patients received a total of 49 fixtures in a 2‐stage procedure. Out of these, 6 fixtures (12%) were lost at abutment connection. In total 313 of the 330 installed mandibular implants were loaded between 6 and 12 months (94.8% success). No further losses occurred in the implants functioning at least 1 year (267 implants) or at least 2 years (59 implants). Statistical analysis (Chi square test) revealed no difference in fixture survival between the treatment modalities. Radiographical analysis after 1 year of functional loading showed the typical bone resorption changes up to the most coronal implant thread in both modalities. Although this study pertains to relatively early loading of 2 years, the results seem to indicate that in the mandible a 1‐stage surgical approach with Brinemark fixtures may be as predictable as the conventional 2‐stage procedure.     

Evaluation of an endosseous titanium implant with a sandblasted and acid‐etched surface in the canine mandible: radiographic results

Previous studies have demonstrated in short‐term experiments that a sandblasted and acid‐etched (SLA) titanium implant had a greater bone‐to‐implant contact than a titanium plasma‐sprayed (TPS) implant in non‐oral bone. In the present study, an SLA implant was compared radiographically to a TPS implant under unloaded and loaded conditions in the canine mandible for up to 15 months. 69 implants were placed in 6 foxhounds. Standardized radiographs were taken at baseline, preload, 3, 6, 9, and 12 months of loading. Loaded implants were restored with gold crowns similar to the natural dentition. Radiographic assessment of the bone response to the implants was carried out by measuring the distance between the implant shoulder and the most coronal bone‐to‐implant contact (DIB) and by evaluation of bone density changes using computer‐assisted densitometric image analysis (CADIA). 5 different areas‐of‐interest (AOI) were defined coronally and apically along the implant. DIB measurements revealed that SLA implants had significantly less bone height loss (0.52mm) than TPS implants (0.69mm) at the preload evaluation ( p =0.0142) as well as at 3 months of loading (0.73mm/1.06mm: p =0.0337). This difference was maintained between the implant types during the 1‐year follow‐up period. The same trend was also evident for CADIA measurements with SLA implants showing higher crestal bone density values when comparing preload to baseline data ( p =0.0890) and 3 months to baseline data ( p =0.0912). No measurable bone density changes were apparent in the apical areas of either implant. These results suggest that SLA implants are superior to TPS implants as measured radiographically in oral bone under unloaded and loaded conditions.     

Evaluation of implant‐supported carbon/graphite fiber‐reinforced poly (methyl methacrylate) prostheses. A longitudinal multicenter study.

Carbon/graphite fiber‐reinforced poly (methyl methacrylate)(CGFP) has been suggested as an alternative framework material for implant‐supported fixed prostheses. The aim of this study was to evaluate CGFP prostheses clinically over time in patients treated with titanium implants of the Brånemark type and to study the handling of the material in the technical production. Twenty‐five patients were fitted with 27 CGFP prostheses supported by 119 implants. Three implants, all in the upper jaw, were lost after loading. After a mean functioning time of 44 months (range 32–56(, 19 prostheses (70%) were still in situ. In all, 5 prostheses fractured, of which 3 were exchanged whereas 2 could be repaired. The fractures were discovered early after loading and located close to the end abutment cylinders. During the follow‐up period, the bone loss around the implants was about the same as earlier reported values for fixed prostheses with cast frameworks. It is concluded that a CGFP framework can be used to form the biocompatible superstructure of implant‐supported prostheses with high precision at a low material cost and with good aesthetic results. The mechanical properties are so far not satisfactory but the method has the potential to be further developed and standardized.     

Initial healing in the dog of submerged versus non‐submerged porous‐coated endosseous dental implants

It has previously been reported that porous‐coated root form endosseous dental implants, became well integrated when used in the traditional 2‐stage surgical approach. In this study, the placement of the implant in a 1‐stage (non‐submerged)technique was to be explored. Implants were placed in the mandibles of dogs, and 2 designs were used differing only in that one (experimental) had a 3mm transgingival extension, permitting it to be exposed lo the oral cavity from the outset. 12 (3 per animal) non‐submerged implants were placed on I side of 4 beagle dogs and 12 control (submerged) implants were placed contralaterally. All implants were allowed to heal for 6 weeks, after which histological preparations were made. 2 of 12 non‐submerged implants were lost due to post‐operative complications: otherwise, all implants healed uneventfully. Histomorphometric analysis revealed bone‐implant contact, as assessed by absolute bone contact (ABC) and contact length fraction (CLF). to be greater for the submerged design, suggesting that bone healing may be delayed with the non‐submerged approach. As well. at this early stage of healing, for both implant designs, ABC and CLF were significantly greater on proximal than on buccal and lingual aspects.     

Bone anchor systems for orthodontic application: a systematic review

This systematic review was performed to investigate the usefulness and clinical effectiveness of skeletal anchorage devices to determine the most effective bone anchor system for orthodontic tooth movement. Literature on bone anchorage devices was selected from PubMed and the Cochrane Library from January 1966 to June 2010. 55 publications regarding miniplates, miniscrews, palatal implants and dental implants as orthodontic anchorage were identified for further analysis. All bone anchorage devices were found to have relatively high success rates and demonstrated their ability to provide absolute anchorage for orthodontic tooth movement. Significant tooth movement could be achieved with low morbidities and good patient acceptance. The reported success rates for the four groups of anchorage systems were generally high with slight variability (miniplates 91.4–100%; palatal implants 74–93.3%; miniscrews 61–100%; dental implants 100%). It was concluded that bone anchorage systems can achieve effective orthodontic movement with low morbidities. The success rate is generally high with slight variability between miniplates, palatal implants, miniscrews and dental implants. Owing to the lack of randomized controlled trials, there is no strong evidence to confirm which bone anchor system is the most effective for orthodontic tooth movement.     

Orthodontic anchorage capacity of short titanium screw implants in the maxilla. An experimental study in the dog.

The aim of this study was to investigate experimentally the effect of long term orthodontic loading on the stability as well as on the peri‐implant bone findings of short titanium screw implants (Bonefit®, submersion depth 6 mm, Ø 4 mm) inserted in regions with reduced vertical bone height. For this purpose, 6 maxillary premolars (₁P₁, ₂P₂, ₃P₃) were extracted from each of 2 foxhounds and reduction of alveolar bone height was performed by osteotomy. After a l6‐week healing period, 8 implants (4 per dog) were inserted in the edentulous areas. Simultaneously, 2 implants (1 per dog) were positioned in the palatal suture (one‐stage surgery). After an 5‐week implant healing period, the fixtures in the Pl/P2 areas ( n = 4) and the palate ( n = 2rpar; were loaded (test implants) by means of transpalatal bars running anteriorly, fixed on the implants in the Pl/P2 areas, and Sentalloy traction springs (‐2 N continuous force) inserted midsagittally between palatal implants and bars (force application period: 26 weeks). The fixtures in the P2/P3 areas served as controls ( n = 4). Clinical measurements and histological evaluation revealed no implant dislocation of the loaded fixtures. These results suggest that short titanium screw implants inserted in the alveolar bone and palatal suture region retain their stability during long‐term orthodontic loading, even following a relatively short unloaded implant healing period. Furthermore, it seems that long‐term orthodontic loading may induce marginal bone apposition adjacent to the implants.     

Long‐term stability of osseointegrated implants in bone regenerted with the membrane technique. 5‐year results of a prospective study with 12 implants.

The purpose of the present clinical study was to evalutate the 5‐year results of the first 12 implants inserted at the University of Berne in regenerated bone following successful ridge augmentation with the membrane technique. The patients were recalled and examined with clinical and radiographic paramenters routinely utilized in prospective studies with standard implants in non‐regenerated bone. Based on clinical and radiographic findings, all 12 implants were considered successfully integrated according to strict criteria of success. The detailed analysis of clinical parameters revealed no differences to results of prospective studies on standard implants in non‐regenerated bone. All implants demonstrated ankylotic stability which was confirmed by a mean Periotest value of ‐2.08. The radiographic analysis showed stable bone crest levels with a mean bone loss between the 1‐ and 5‐year examination of 0.30 mm. However, 2 implants exhibited a bone loss of more than 1 mm between the 1‐ and 5‐year examination. Therefore, the prognosis of these 2 implants seems questionable at the present time. It can be concluded that bone regenerated with the membrane technique reacts to implant placement like non-regenerated bone, since all 12 implants achieved successful tissue integration with functional ankylosis. Furthermore, this bone is also load‐bearing, since all 12 implants maintained osseointegration over a 5‐year period.     

Short epithetic implants for orthodontic anchorage in the paramedian region of the palate

Orthodontic movement of teeth often requires maximum anchorage, so that additional resistance must be added to teeth to avoid reaction to reciprocal forces. Thus, use of endosseous implants may be a valuable alternative for ensuring stable intraoral anchorage. This study was designed to evaluate the efficacy of short epithetic implants for orthodontic anchorage in the paramedian region of the palate. Twenty-one patients (15 female, 6 male; mean age 25.8+/-9.9 yrs, min 12.7, max. 48.1) were included in this study. Following adequate preoperative planning, an implant system with reduced length, which had already been used for anchorage of epitheses, was placed in the paramedian region avoiding the anterior palatine suture. After a mean period of 4 months with unloaded healing, the implants were subjected to direct or indirect orthodontic loading. Despite varying bone quality and varying vertical bone volume in this region, adequate primary stability was achieved for all of the implants. No implant was lost during the healing period. Three out of the 21 implants placed were considered as failures. Two implants loosened shortly after the start of orthodontic loading. One of these was lost at a later stage due to peri-implant inflammation, while the other one was left in place during the 9-month follow-up period because no inflammation developed and this implant is still indirectly included in the orthodontic treatment. Another implant loosening was observed after 8.5 months following direct loading with 8 N. This implant was also lost due to peri-implant inflammation. The time-related survival probability was 84.8% after 22.9 months. As yet, 4 implants have been removed due to completion of orthodontic treatment. The results of this study indicate that short epithetic implants are suitable to achieve maximum anchorage in the paramedian region of the hard palate in orthodontic treatment.     

The reliability of pocket probing around screw‐type implants

This study involved 108 patients (age 38–82 years) rehabilitated with overdentures in the lower jaw supported by 2 endosseous screw‐shaped implants. At each follow‐up visit, the clinical attachment level (PAL) around the implants was assessed with a Merrit‐B probe or a constant force electronic probe, Peri‐probe, and biannually parallel long‐cone radiographs were taken to locate the marginal bone level. These data were used to examine the relationship between bone and attachment level estimations around implants. As a mean, bone level was scored 1.4 mm apically of PAL and this difference remained constant with time. The Pearson correlation coefficient between bone level and PAL, for mesial and distal sites, was 0.67 and 0.61 for the Merrit‐B probe, and 0.76 and 0.65, respectively for the Peri‐probe. The highest correlations were obtained for sites with a healthy gingiva or in absence of intra‐bony craters. Duplicate PAL registrations showed a standard deviation for the intra‐examiner variability of 0.37 (Peri‐probe) or 0.40 mm (Merrit‐B probe) with more than 90% of the variation within 0.5 mm. The mean difference in PAL between Merrit‐B probe or Peri‐probe was 0.05 mm. It was concluded that the clinical attachment level determination is a reliable indicator for bone level around implants with a moderate healthy gingiva.     

Initial interfacial healing events around calcium phosphate (Ca‐P) coated oral implants

The bone response to different calcium phosphate (Ca‐P) coated and non‐coated titanium implants was evaluated in a goat animal model. Two types of Ca‐P coatings have been investigated: an experimental plasma‐spray bi‐layered Ca‐P coating (FA‐HA) and an amorphous RF magnetron sputter coating (Ca‐P‐a). Fifty‐four conical screw shaped implants were inserted in the lateral and medial femoral condyles of 18 Saanen goats. After implantation periods of 3, 12 and 24 days, the bone‐implant interface was evaluated histologically and histomorphometrically. Light microscopical evaluation revealed that bone formation on the Ca‐P coated implants proceeded faster. At 24 days higher percentages of bone contact were measured for both Ca‐P coated implants than for non‐coated implants. However, this difference was only significant for the FA‐HA coated implants. On basis of these findings. we concluded that Ca‐P coatings show improved bone response due to an initial difference in bone cell response.     

Single‐tooth replacement by osseointegrated Brånemark implants. A retrospective study of 82 implants.

The aim of the study was to evaluate the outcome of single‐tooth restorations on Brånemark implants performed during the period 1986–1989. The material comprised 58 consecutive patients with 82 implants. The observation period varied from 1 to 5 years. Two implants were lost. both of them before loading. The overall survival rate was 97.6%. Radiographic follow‐up was performed for 72 implants after 1 year and for 51 implants after 2 years. The bone loss during the first year was on average 0.6±0.1 mm and during the second year 0.1±0.1 mm. Although the observation time for most of the patients was only 2 years, the results indicate that the outcome of single‐tooth restorations may be as favorable as for implants in edentulous jaws.     

Peri-implant bone response to orthodontic loading: Part 1. A histomorphometric study of the effects of implant surface design.

INTRODUCTION: Bone response to orthodontic loading was compared histomorphometrically around 2 different types of osseointegrated implants (porous surfaced and machined threaded) to determine their suitability for orthodontic anchorage. METHODS: Five beagles each received 3 implants of each design in contralateral mandibular locations. After a 6-week initial healing period, abutments were placed, and, 1 week later, the 2 mesial implants on each side were orthodontically loaded for 22 weeks. All implants remained osseointegrated throughout orthodontic loading except for 1 threaded implant that loosened. Light miscroscopy and back-scattered scanning electron microscopy were used to compare responses around the 2 implant designs. RESULTS: Porous-surfaced implants had higher marginal bone levels (P +/- .025) and less relative implant displacement than threaded implants. CONCLUSIONS: Differences in implant surface design can lead to differences in peri-implant bone height and bone-to-implant contact. Porous-surfaced implants might be successful as orthodontic anchorage units.     

Direct versus indirect loading of orthodontic miniscrew implants—an FEM analysis

Objective

The mesialization of molars in the lower jaw represents a particularly demanding scenario for the quality of orthodontic anchorage. The use of miniscrew implants has proven particularly effective; whereby, these orthodontic implants are either directly loaded (direct anchorage) or employed indirectly to stabilize a dental anchorage block (indirect anchorage). The objective of this study was to analyze the biomechanical differences between direct and indirect anchorage and their effects on the primary stability of the miniscrew implants.

Materials and methods

For this purpose, several computer-aided design/computer-aided manufacturing (CAD-CAM)-models were prepared from the CT data of a 21-year-old patient, and these were combined with virtually constructed models of brackets, arches, and miniscrew implants. Based on this, four finite element method (FEM) models were generated by three-dimensional meshing. Material properties, boundary conditions, and the quality of applied forces (direction and magnitude) were defined. After solving the FEM equations, strain values were recorded at predefined measuring points. The calculations made using the FEM models with direct and indirect anchorage were statistically evaluated.

Results

The loading of the compact bone in the proximity of the miniscrew was clearly greater with direct than it was with indirect anchorage. The more anchor teeth were integrated into the anchoring block with indirect anchorage, the smaller was the peri-implant loading of the bone.

Conclusions

Indirect miniscrew anchorage is a reliable possibility to reduce the peri-implant loading of the bone and to reduce the risk of losing the miniscrew. The more teeth are integrated into the anchoring block, the higher is this protective effect.

Clinical relevance

In clinical situations requiring major orthodontic forces, it is better to choose an indirect anchorage in order to minimize the risk of losing the miniscrew.