Bone resorption around fixtures in edentulous patients treated with mandibular fixed tissue-integrated prostheses

Immediate Implant Placement After Removal of a Failed Implant: A Clinical and Histological Case Report

The purpose of this study was to evaluate the clinical success of an implant placed immediately after the explantation of a fractured blade implant. A healthy 58-year-old male nonsmoker presented with a fractured blade implant that had been subjected to biomechanical overload. A new blade implant was placed immediately after the removal of the fractured one. The new implant was placed with a composite graft of collagen gel and corticocancellous porcine bone and covered with a bioabsorbable membrane. Radiographic evaluation at 6 months postoperation showed complete bone healing. No residual bone defect was observed or probed during the uncovering phase; moreover, no mobility, pain, suppuration, or presence of peri-implant radiolucency were observed at the second-stage surgery.

The change in retentive values of locator attachments and hader clips over time

PURPOSE

The aim of this study was to examine early changes in retentive values of implant overdenture attachments during multiple pulls.

MATERIALS AND METHODS

Two implant attachment systems (Hader bar and clip, Locator system) were used in this study. The experimental groups were divided into yellow Hader clips, white Locator attachments, and green Locator attachments. Each group consisted of 21 matrix attachments. The attachments were placed into a custom-made acrylic resin block seated passively on another acrylic block containing a Hader bar or two Locator abutments with different angulations. Each attachment was subjected to 20 consecutive pulls using a universal testing machine. The peak load-to-dislodgement of the attachments after each pull was documented, and the percent reduction of the peak load-to-dislodgement was calculated. One-way ANOVA and Tukey's honestly significant difference test were used for data analyses. A p < or = 0.05 was considered significant.

RESULTS

There was a significant difference in the percent reduction in peak load-to-dislodgement between the attachments after the first pull (p= 0.005) and after the final pull (p= 0.0001). The yellow Hader clips exhibited the least percent reduction in peak load-to-dislodgement (6.50 +/- 3.59%) after the first pull, followed by the white Locator attachments (8.60 +/- 4.42%); the green Locator attachments exhibited the greatest reduction (11.05 +/- 4.94%).

CONCLUSION

The results of this in vitro study demonstrate that retentive values of the Locator attachments are reduced significantly after multiple pulls. Although this reduction might not be noticeable to the patient, it is recommended that the clinician place and remove the overdenture multiple times before delivery.

Should edentulous patients be constrained to removable complete dentures? The use of dental implants to improve the quality of life for edentulous patients

BACKGROUND

Nowadays, there is some speculation among dental educators that the need for complete dentures will significantly decrease in the future and that training in their provision should be removed from the dental curriculum.

OBJECTIVE

To sensitise the reader to the functional shortcomings of complete denture therapy in the edentulous patient and present restorative options including implants to improve edentulous quality of life in these patients.

METHODS

Information retrieval followed a systematic approach using PubMed. English articles published from 1964 to 2008, in which the masticatory performance of patients with implant-supported dentures was assessed by objective methods and compared with performance with conventional dentures, were included.

RESULTS

National epidemiological survey data suggested that the adult population in need of one or two complete dentures will increase from 35.4 million adults in 2000 to 37.9 million adults in 2020. Clinical studies have showed that the ratings of general satisfaction were significantly better in the patients treated with implant overdentures post-delivery compared with the complete denture users. In addition, the implant group gave significantly higher ratings on comfort, stability and ability to chew. Furthermore, patients who received mandibular implant overdentures had significantly fewer oral health-related quality of life problems than did the conventional group.

CONCLUSION

Implant-supported dentures including either complete overdentures or a hybrid prosthesis significantly improve the quality of life for edentulous patients compared with conventional removable complete dentures. Therefore, the contemporary dental practitioner should consider other options as well as conventional removable complete dentures to restore edentulous patients.

Integrin mediated attachment of periodontal ligament to titanium surfaces

OBJECTIVE

Reducing the force between the implant and the bone by recapitulating a similar matrix has the potential to reduce implant failure. To begin to pursue the goal of creating a periodontal ligament interface between a dental implant and bone, the mechanism of cellular attachment to dental implant surfaces must be characterized.

METHODS

In this study we examined the role of integrin receptors in the attachment of periodontal ligament fibroblasts to titanium surfaces utilized on dental implants; those surfaces included smooth polished titanium, acid pickled titanium, ground titanium, sandblasted and acid etched titanium, non-oxidized titanium that has been sandblasted and acid etched, hydroxyapatite coated titanium, titanium plasma sprayed or uncoated titanium. For these studies integrin mediated fibroblast attachment was blocked by the integrin blocking peptide GRGDSP or anti-integrin beta1 antibody or a combination of the two. Quantitation of periodontal ligament fibroblast attachment was completed by counting cells on the various implant surfaces after culturing in vitro for 24h with and without the integrin receptor blockers.

RESULTS

Antibody and peptide treatment significantly reduced the number of fibroblasts cells attached to the various implant surfaces but this effect varied significantly depending on the surface. Moreover, increased levels of peptide further decreased fibroblasts attachment in a dose dependent manner.

SIGNIFICANCE

Blocking studies suggest first, that integrin receptors function in periodontal ligament attachment to titanium surfaces and second, that different integrin subunits are important in attachment to a particular surface.

A 10-year prospective study of ITI dental implants placed in the posterior region. II: Influence of the crown-to-implant ratio and different prosthetic treatment modalities on crestal bone loss

OBJECTIVE

To evaluate the influence of the crown-to-implant ratio (C/I) ratio and different implant prosthetic treatment modalities on crestal bone loss around dental implants placed in the posterior region.

MATERIAL AND METHODS

A total of 192 ITI dental implants were consecutively placed in premolars and molars of 83 partially edentulous patients. All implants were restored by means of ceramic-to-metal fused fixed partial dentures or a single crown. Patients were followed as part of a prospective longitudinal study focusing on implant success. Surgical, radiographic and clinical variables were collected at the 1-year recall after implant placement and at the most recent clinical evaluation. Radiographic parameters were evaluated on periapical radiographs taken with a standardized long-cone paralleling technique. Implant restorations were divided into three groups according to their respective clinical C/I ratios: (a) 0-0.99, (b) 1-1.99 and (c) >or=2.

RESULTS

The mean clinical C/I ratio was 1.77+/-0.56 mm. A total of 51 implants (26.5%) showed a clinical C/I ratio equal to or greater than 2. In this group, three implants failed, giving a cumulative survival rate of 94.1%. Crestal bone loss was -0.34+/-0.27 mm in group a, -0.03+/-0.15 mm in group b and -0.02+/-0.26 mm in group c. Differences among groups were statistically significant (P=0.009). Mode of retention, splinting or presence of cantilever extensions did not have an effect on crestal bone loss around ITI dental implants.

CONCLUSIONS

Implant restorations with C/I ratios between 2 and 3 may be successfully used in the posterior areas of the jaw.

Bone level changes at axial- and non-axial-positioned implants supporting fixed partial dentures. A 5-year retrospective longitudinal study

AIM

The aim of this study was to retrospectively analyze the potential influence of implant inclination on marginal bone loss at freestanding, implant-supported, fixed partial dentures (FPDs) over a 5-year period of functional loading.

MATERIAL AND METHODS

The material comprised 38 periodontally treated, partially dentate patients with a total of 42 free-standing FPDs supported by implants of the Astra Tech System. Mesio-distal inclination of the implants in relation to a vertical axis perpendicular to the occlusal plane was measured with a protractor on standardized photographs of the master cast. The two tail quartiles of the distribution of the implants with regard to the implant inclination were defined as axial-positioned (mean 2.4 degrees; range 0-4 degrees) and non-axial-positioned implants (mean 17.1 degrees; range 11-30 degrees), respectively. For FPDs supported by two implants, both the mesial-distal and buccal-lingual inter-implant inclination was measured. The primary outcome variable was change in peri-implant bone level from the time of FPD placement to the 5-year follow-up examination. Comparison between axial- and non-axial-positioned implants was performed by the use of a Mann-Whitney U-test. Spearman's correlation analysis was used to analyze relationships between inter-implant inclination (mesial-distal and buccal-lingual) and 5-year bone level change on the FPD level.

RESULTS

The 5-year mean bone level change amounted to 0.4 mm (SD 0.97) for the axial and 0.5 mm (0.95) for non-axial-positioned implants (P>0.05). For the FPDs supported by two implants, the mean inter-implant inclination was 9.2 degrees (1-36 degrees) in the mesial-distal direction and 6.7 degrees (0-24 degrees) in the buccal-lingual direction. Correlation analysis revealed lack of statistically significant correlation between inter-implant inclination (mesial-distal and buccal-lingual) and 5-year bone level change (r=-0.19 and r=-0.32, respectively).

CONCLUSION

The study failed to support the hypothesis that implant inclination has an effect on peri-implant bone loss.

Impact of implant overloading on the peri-implant bone in inflamed and non-inflamed peri-implant mucosa

OBJECTIVE

To assess the impact of overloading on peri-implant bone level and the bone-to-implant contact (BIC) in the presence of healthy or inflamed peri-implant tissues.

MATERIALS AND METHODS

Four screw-shaped machined implants were placed bilaterally in the mandible of four beagle dogs and left submerged for 3 months. Prosthetic abutments were connected either in supra-occlusal contact with the opposite teeth (overloaded) or in infra-occlusal position (unloaded). In each dog, cotton floss ligatures were placed unilaterally around abutments to promote plaque accumulation; the contralateral side was brushed three times a week. There were four experimental sites, two implants in each: loaded uninflamed (LU), loaded inflamed (LI), unloaded uninflamed (UU), and unloaded inflamed (UI). Clinical and radiographic parameters were recorded at baseline and every 3 months throughout the observation period. At 12 months, the dogs were sacrificed and histomorphometric analysis was performed.

RESULTS

Implants with ligature-induced peri-implantitis presented high inflammatory indices throughout the observation period. Clinical parameters did not change from baseline for both LU and UU. Loading significantly increased the percentage of BIC (BIC%) (P<0.05) and slightly increased crestal bone resorption, but not apical to the implant neck. Both LI and UI groups showed significant peri-implant bone loss (P<0.01), mostly horizontal on the buccal aspect and angular on the lingual aspect, which exposed implant threads. Loading significantly (P<0.05) increased implant thread exposure due to buccal and lingual vertical bone resorption.

CONCLUSIONS

In the presence of uninflamed peri-implant mucosa, overloading of implants in the dog model increased BIC% and slightly reduced marginal bone level. However, resorption did not progress beyond the implant neck. Overloading aggravated the plaque-induced bone resorption when peri-implant inflammation was present.

Radiological and clinical follow-up of machined- and anodized-surface implants after mean functional loading for 33 months

The purpose of this retrospective study was to compare peri-implant bone loss and mucosal conditions around machined-surface (MS) and anodized-surface (AS) interforaminal implants in the mandible at least 30 months after placement. Fifty patients, each treated with four interforaminal screw-type implants consecutively, were included. Thirty-one patients (62%) with a total number of 124 implants (64 MS and 60 AS implants, both Brånemark type MKIII) were available for follow-up. Rotational panoramic radiographs were used for evaluating marginal bone loss. Clinically, marginal plaque index (mPI), bleeding on probing (BOP) and pocket probing depth (PPD) were evaluated. AS implants showed significantly less marginal bone loss than MS implants (-1.17+/-0.13 vs. -1.42+/-0.13 mm; P=0.03). Marginal bone loss around distal implants was less pronounced at AS implants (-1.05+/-0.14 mm) when compared with MS implants (-1.46+/-0.14 mm; P=0.05). Within the smoking group, there was less peri-implant bone loss around AS implants than around MS implants (-1.08+/-0.27 vs. -1.83+/-0.2; P=0.04). No differences between MS and AS implants were found with respect to mPI (57% vs. 67%), BOP (21% vs. 17%) and mean PPD (2.59+/-0.29 vs. 2.56+/-0.28 mm). Overall, both types of implants, in combination with bar-supported overdentures, can produce excellent long-term results in the interforaminal edentulous mandible with less peri-implant bone loss around rough implant surfaces, which had beneficial effects at distal implants and in smokers.

Influence of interimplant distance on papilla formation and bone resorption: a clinical-radiographic study in dogs

Implant esthetics has been the focus of attention for the past decade, and one vital issue is the effect of interimplant distance on interimplant papilla formation and crestal bone loss. The aim of this study was to evaluate the effect of 1, 2, and 3 mm of interimplant distance on papilla formation and crestal resorption in submerged and nonsubmerged Ankylos implants after prosthetic restoration. Bilateral mandibular premolars of 7 dogs were extracted, and after 12 weeks each dog received 8 implants. Implants were placed so that 3 interimplant distances were created at 1 mm (group 1), 2 mm (group 2), and 3 mm (group 3). The sides and the position of the groups were randomly selected. Twelve weeks after placement, the implants received metallic prostheses that allowed 5 mm of space between the prosthetic contact point (CP) and the crestal bone (CB). After 8 weeks, the distance between the CP and the papilla (CP-P) and the gingival height at the distal proximal aspect of the prosthesis (CP-DE) was clinically measured. Radiographic images were obtained to measure the distance of the CP to the CB within the interimplant surfaces (CP-IP) and adjacent to the edentulous surfaces (CP-ED). The clinical measurement of CP-P for submerged and nonsubmerged implants was 3.57+/-1.17 mm and 3.10+/-0.82 mm for group 1, 3.57+/-0.78 mm and 3.16+/- 0.87 mm for group 2, and 3.35+/- 0.55 mm and 3.07+/-0.93 mm for group 3. The CP-DE was 3.25+/-0.77 mm for submerged and 2.78+/- 0.64 mm for nonsubmerged implants. The CP-IP for the submerged and nonsubmerged implants was 6.91+/-0.95 mm and 7.68+/-2.73 mm for group 1, 7.46+/-1.43 mm and 5.87+/-1.71 mm for group 2, and 7.72+/-0.81 mm and 7.59+/-1.33 mm for group 3. The CP-ED was 6.77+/-1.33 mm for submerged implants and 6.03+/-1.58 mm for nonsubmerged implants. There were no statistical significant differences for any of the measured parameters. We conclude that when the distance from the CP to the CB was 5 mm, interimplant distances of 1 to 3 mm did not affect papilla formation or crestal resorption of submerged or nonsubmerged implants in the dog model.

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.

Influence of forces on peri-implant bone

Occlusal forces affect an oral implant and the surrounding bone. According to bone physiology theories, bones carrying mechanical loads adapt their strength to the load applied on it by bone modeling/remodeling. This also applies to bone surrounding an oral implant. The response to an increased mechanical stress below a certain threshold will be a strengthening of the bone by increasing the bone density or apposition of bone. On the other hand, fatigue micro-damage resulting in bone resorption may be the result of mechanical stress beyond this threshold. In the present paper literature dealing with the relationship between forces on oral implants and the surrounding bone is reviewed. Randomized controlled as well as prospective cohorts studies were not found. Although the results are conflicting, animal experimental studies have shown that occlusal load might result in marginal bone loss around oral implants or complete loss of osseointegration. In clinical studies an association between the loading conditions and marginal bone loss around oral implants or complete loss of osseointegration has been stated, but a causative relationship has not been shown.

Implant maintenance

Endosseous root-form implants have become an integral part of dental reconstruction in partially and fully edentulous patients. The long-term prognosis of an implant is related directly to routine assessment and effective preventive care. To maintain healthy tis-sues around dental implants, it is important to institute an effective maintenance regimen. Different regimens have been suggested, but it is unclear which are the most effective. This article evaluates the literature regarding implant maintenance. Factors affecting the soft tissue surrounding endosseous root-form implants are discussed, and procedures for assessment of the implant and the treatment of reversible disease in implant maintenance are outlined.

Tissue Characteristics at Microthreaded Implants: An Experimental Study in Dogs

PURPOSE

The aim of the present study was to analyze bone tissue reactions at implants with and without a microthread configuration.

MATERIALS AND METHODS

In six beagle dogs, one test and two control implants were installed in one side of the mandible. While both implant types had a similar dimension and surface roughness, the test implants were designed with a microthread configuration in the marginal portion. Abutment connection was performed after 3 months. Another 3 months later, fixed partial dentures (FPDs) were cemented to the maxillary canine and premolars and FPDs were connected to the implants in the mandible. Ten months later, the animals were sacrificed and biopsies from each implant region were processed for histological analysis. Radiographs were obtained at implant placement after FPD connection and at the termination of the experiment.

RESULTS

The radiographic examination revealed that the marginal bone level was well preserved at both test and control implants during the entire 16-month period. The degree of bone-implant contact within the marginal portion of the implants was significantly higher at the test (microthread) implants (81.8%) than at the control implants (72.8%).

CONCLUSIONS

It was suggested that the microthread configuration offered improved conditions for osseointegration.

Syncrystallization: A Technique for Temporization of Immediately Loaded Implants with Metal-Reinforced Acrylic Resin Restorations

BACKGROUND

Rigid temporization has been recognized to have a significant impact on the peri-implant tissue response in immediate implant loading since it reduces the mechanical stress exerted on each implant.

PURPOSE

A successful protocol for immediate loading of multiple implants depends on an adequate fixation and immobility of the implants to prevent the risk of micromovements in relation to the surrounding bone. The objective of this article was to evaluate a prosthetic concept for an accelerated rigid splinting of multiple implants for same-day immediate loading with metal-reinforced provisional restorations using a technique of welding temporary implant abutments with a prefabricated titanium bar directly in the oral cavity (syncrystallization).

MATERIALS AND METHODS

Between June 2004 and January 2005, immediate loading of threaded implants with a metal- reinforced acrylic resin provisional restoration at stage 1 surgery was evaluated in 40 consecutive patients. A total of 192 implants were placed in selected edentulous or partially edentulous patients using the syncrystallization technique. Once the titanium bar was welded intraorally to the abutments, opaque was applied and the provisional restoration was relined and screw-retained the same day. In addition, a comparison of deformations and stress distributions in implant-supported, metal-reinforced and nonmetal-reinforced resin provisional restorations was analyzed in the edentulous mandible by a three-dimensional finite element model (FEM).

RESULTS

All of the 192 rigidly temporized immediately loaded implants osseointegrated. An implant success rate of 100% was achieved over a period of 6 months postplacement. No fracture or luting cement failure of the provisional restoration occurred during the observation time. Compared to mere acrylic superstructures, a significant reduction of deformation and strain within metal-reinforced provisional restorations was detected by FEM analysis.

CONCLUSION

The results of this study indicate that the syncrystallization technique allows an expedite and adequate rigid splinting of multiple immediately loaded implants. The advantages of the technique are: (1) reduction of treatment time for immediate temporization at stage 1 surgery; (2) predictable fixation and immobility of implants in the early stages of bone healing; and (3) less time for repairing provisional restorations as a result of no or rare fracture.

Bacterial Plaque Colonization Around Dental Implant Surfaces

PURPOSE

To examine the distribution of bacteria into the internal and external surfaces of failed implants using histologic analysis.

MATERIALS AND METHODS

There were 10 failed pure titanium and 5 failed hydroxyapatite-coated titanium implants consecutively removed various years after their placement. Criteria for fixture removal were peri-implant radiolucency and clinical mobility. The mobile fixtures were retrieved with the patients under local anesthesia. Fixtures were removed maintaining the abutments with the aim to observe the bacterial infiltration at the level of abutment/implant interface and on the implant surface.

RESULTS

A thin radiolucent space was always present around all the failed implants. The abutments screws were tightly secured in all clinical cases. The bacterial cells were composed of cocci and filaments, which were adherent to the implant surface with an orientation perpendicular to the long axis of the implant. All the specimens included in this study showed bacteria at the level of implant/abutment interface.

CONCLUSIONS

Histologic analysis at the level of abutment/implant interface in 2-stage implants identified heavy bacterial colonization. These findings appear to support those studies showing bacteria penetration at the level of the micro-gap, which can legitimate the hypothesis that the micro-gap at the bone level could present a risk for bone loss caused by bacterial colonization.

Dental implants in patients with bruxing habits

Bruxism (teeth grinding and clenching) is generally considered a contraindication for dental implants, although the evidence for this is usually based on clinical experience only. So far, studies to the possible cause-and-effect relationship between bruxism and implant failure do not yield consistent and specific outcomes. This is partly because of the large variation in the literature in terms of both the technical aspects and the biological aspects of the study material. Although there is still no proof for the suggestion that bruxism causes an overload of dental implants and of their suprastructures, a careful approach is recommended. There are a few practical guidelines as to minimize the chance of implant failure. Besides the recommendation to reduce or eliminate bruxism itself, these guidelines concern the number and dimensions of the implants, the design of the occlusion and articulation patterns, and the protection of the final result with a hard occlusal stabilization splint (night guard).

Bone reactions to longstanding functional load at implants: an experimental study in dogs

OBJECTIVES

The aims of the present investigation were (i) to study marginal bone level alterations following implant installation, abutment connection and functional loading and (ii) to analyse bone tissue reactions to functional load.

MATERIAL AND METHODS

Six beagle dogs, about 1-year old, were used. All mandibular pre-molars were extracted. Three months later four implants of the Astra Tech Implants Dental System were installed in one side of the mandible and four standard fixtures of the Brånemark System were placed in the contralateral side of the mandible. Abutment connection was performed 3 months later and a plaque control programme was initiated. Three months after abutment connection fixed partial dentures (FPDs) made in gold were cemented to the maxillary canines and pre-molars. FPDs were also connected to the three posterior implants in each side of the mandible, while the mesial implant in each side was used as an unloaded control. Radiographs were obtained from all implant sites following implant installation, abutment connection and FPD placement. Ten months after the FPD placement the radiographic examination was repeated. The animals were sacrificed and biopsies from all implant sites were obtained and prepared for histological analysis.

RESULTS

The radiographic analysis revealed that largest amount of bone loss occurred following implant installation and abutment connection and that this loss was more pronounced at Brånemark than at Astra implants. The bone level alterations that were observed at implants exposed to 10 months of functional load in both implant systems were small and did not differ from control sites. The histological analysis revealed that implants exposed to functional load exhibited a higher degree of bone-to-implant contact than control implants in both implant systems.

CONCLUSION

It is suggested that functional load at implants may enhance osseointegration and does not result in marginal bone loss.

Influence of alcohol and tobacco habits on peri-implant marginal bone loss: a prospective study

A prospective clinical study was conducted to explore the possible link between peri-implant bone loss and the widespread habits of tobacco smoking and alcohol consumption. One hundred and eighty-five patients who received 514 implants were followed up for 3 years. Peri-implant marginal bone loss was evaluated by digital panoramic radiography and image analysis techniques. Multivariate analysis showed that peri-implant marginal bone loss was significantly related to a daily consumption of >10 g of alcohol, tobacco use and increased plaque levels and gingival inflammation. The present results indicate that daily alcohol consumption and tobacco use may have a negative influence on predictable long-term implant treatment outcomes, producing peri-implant bone loss and compromising restorative treatment with implant-supported prostheses.

A Positive Correlation Between Occlusal Trauma and Peri-implant Bone Loss: Literature Support

The relationship between occlusal overload and peri-implant bone loss remains a controversial topic in implant dentistry. A causal relationship between the incidence of marginal bone loss next to an implant and occlusal overload implies a treatment plan and occlusal scheme would benefit from a force management approach. A MEDLINE-assisted and hand search of peer-reviewed English literature and relative textbooks were used for a selective review of articles addressing biomechanical stress and bone loss in cellular biomechanics, engineering principles, mechanical properties of bone, animal studies, clinical reports, bone physiology, and implant design biomechanics. These papers demonstrate occlusal overload on implants may increase the incidence of marginal bone loss.

Functional Restoration of Implants on the Day of Surgical Placement in the Fully Edentulous Mandible: A Case Series

PURPOSE

The purpose of this article is to report the clinical experience and outcome of a study of the functional rehabilitation of 16 completely edentulous mandibles with immediately loaded cross-arch screw-retained hybrid prostheses at the University of Southern California.

MATERIALS AND METHODS

After signing informed consent forms 16 patients (9 male, 7 female) aged 47 to 84 years (mean age, 62.6+/-11.6 years) received 90 Brånemark System Mk III dental implants (Nobel Biocare USA, Yorba Linda, CA, USA). Stability and radiographs of the dental implants were evaluated at the time of surgery, at 3 months, at 1 year, and at 3 years post loading.

RESULTS

Three implants failed to meet the criteria of success, bringing the cumulative success rate to 96.6%, with a 100% prosthetic success rate at 3 years. Thirty-nine (43.3%) of the dental implants placed were 15 mm in length. Seventy-seven (85.5%) of the dental implants were placed in high-density bone. At 3 years post loading, the average bone loss was -1.2+/-0.1 mm.

CONCLUSION

Within the limitations of this study, restoration of implants by unreinforced hybrid prostheses at the time of placement provided satisfactory results. The outcome was stable at 3 years post restoration. Mandibular rehabilitation by functional loading of the implants on the day of the insertion requires the comprehension and proper application of surgical and restorative principles.

Bone level change at implant-supported fixed partial dentures with and without cantilever extension after 5 years in function

OBJECTIVE

The aim of this study was to retrospectively analyze whether the inclusion of cantilever extensions increased the amount of marginal bone loss at free-standing, implant-supported, fixed partial dentures (FPDs) over a 5-year period of functional loading.

MATERIAL AND METHODS

The patient material comprised 45 periodontally treated, partially dentate patients with a total of 50 free-standing FPDs supported by implants of the Astra Tech System. Following FPD placement (baseline) the patients were enrolled in an individually designed supportive care program. A set of criteria was collected at baseline to characterize the FPDs. The primary outcome variable was change in peri-implant bone level from the time of FPD placement to the 5-year follow-up examination. The comparison between FPDs with and without cantilevers was performed at three levels: FPD level, implant level, and surface level. Bivariate analysis was performed by the use of the Mann-Whitney U-test and stepwise regression analysis was utilized to evaluate the potential influence of confounding factors on the change in peri-implant bone level.

RESULTS

The overall mean marginal bone loss for the implant-supported FPDs after 5 years in function was 0.4 mm (SD, 0.76). The bone level change at FPDs placed in the maxilla was significantly greater than that for FPDs in the mandible (0.6 versus 0.2 mm; p<0.05). No statistically significant differences were found with regard to peri-implant bone level change over the 5 years between FPDs with and without cantilevers at any of the levels of comparisons. The multivariate analysis revealed that the variables jaw of treatment and smoking had a significant influence on peri-implant bone level change on the FPD level, but not on the implant or surface levels. The model explained only 10% of the observed variance in the bone level change.

CONCLUSION

The study failed to demonstrate that the presence of cantilever extensions in an FPD had an effect on peri-implant bone loss.

A review of selected dental literature on evidence-based treatment planning for dental implants: Report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics

This literature review summarizes research with the aim of providing dentists with evidence-based guidelines to apply when planning treatment with osseointegrated implants. Peer-reviewed literature published in the English language between 1969 and 2003 was reviewed using Medline and hand searches. Topics reviewed include systemic host factors such as age, gender, various medical conditions, and patient habits, local host factors involving the quantity and quality of bone and soft tissue, presence of present or past infection and occlusion, prosthetic design factors, including the number and arrangement of implants, size and coatings of implants, cantilevers and connections to natural teeth, and methods to improve outcomes of implant treatment in each category. The review demonstrated that there is no systemic factor or habit that is an absolute contraindication to the placement of osseointegrated implants in the adult patient, although cessation of smoking can improve outcome significantly. The most important local patient factor for successful treatment is the quality and quantity of bone available at the implant site. Specific design criteria are provided, including guidelines for spacing of implants, size, materials, occlusion, and fit. Limitations in the current body of knowledge are identified, and directions for future research are suggested.

Therapy of peri-implantitis with resective surgery

The purpose of this randomized clinical trial was to compare the clinical outcome of two different surgical approaches for the treatment of peri-implantitis. Seventeen patients with ITI(R) implants were included consecutively over a period of 5 years. The patients were randomized with a lottery assignment. Ten patients were treated with resective surgery and modification of surface topography (test group). The remaining seven patients were treated with resective surgery only (control group). Clinical parameters (suppuration, modified plaque index - mPI, modified bleeding index - mBI, probing pocket depth - PPD, pseudopocket - DIM, mucosal recession - REC, probing attachment level - PAL) were recorded at baseline, as well as 6, 12, 24 and 36 months after treatment. The cumulative survival rate for the implants of the test group was 100% after 3 years. After 24 months, two hollow-screw implants of control group were removed because of mobility. Consequently, the cumulative survival rate was 87.5%. The recession index in the control group was significantly lower than in the test group at 24 months (Student's t-value of -2.14). On the contrary, control group showed higher PPD, PAL and mBI indexes than test group (Student's t-values of +5.5, +2.4 and +9.61, respectively). The PPD and mBI indexes for the implants of the control group were significantly higher at baseline than 24 months later (Student's t-values of +3.18 and +3.33, respectively). Recession and PAL indexes resulted in values significantly lower than baseline (Student's t-values of -4.62 and -2.77, respectively). For the implants of the test group PPD and mBI indexes were significantly higher at baseline than 36 months after (Student's t-values of +11.63 and +16.02, respectively). Recession index resulted in values significantly lower at baseline (Student's t-value of -5.05). No statistically significant differences were found between PAL index measurement at baseline and 36 months later (Student's t-value of +0.89). In conclusion, resective therapy associated with implantoplasty seems to influence positively the survival of oral implants affected by inflammatory processes.

Occlusal considerations in implant therapy: clinical guidelines with biomechanical rationale

Due to lack of the periodontal ligament, osseointegrated implants, unlike natural teeth, react biomechanically in a different fashion to occlusal force. It is therefore believed that dental implants may be more prone to occlusal overloading, which is often regarded as one of the potential causes for peri-implant bone loss and failure of the implant/implant prosthesis. Overloading factors that may negatively influence on implant longevity include large cantilevers, parafunctions, improper occlusal designs, and premature contacts. Hence, it is important to control implant occlusion within physiologic limit and thus provide optimal implant load to ensure a long-term implant success. The purposes of this paper are to discuss the importance of implant occlusion for implant longevity and to provide clinical guidelines of optimal implant occlusion and possible solutions managing complications related to implant occlusion. It must be emphasized that currently there is no evidence-based, implant-specific concept of occlusion. Future studies in this area are needed to clarify the relationship between occlusion and implant success.

Reversible and Irreversible Peri-implant Lesions: Report and Etiopathogenic Analysis of 7 Cases

The purpose of this report is to review the aberrations in the integration process of cylindrical endosseous implants, though such aberrations are seldom observed. These issues are treated according to the following scheme: (1) infectious lesions, which consist of peri-implantitis, intraosseous infectious foci, and septic voids; (2) transitory lesions; (3) lesions related to occlusal overload; and (4) healing defects. In this report, we illustrate these categories with patient histories and discuss the clinical findings and etiopathogenies.

The safety and efficacy of a powered toothbrush on soft tissues in patients with implant-supported fixed prostheses

The safety, efficacy and acceptability of an oscillating/rotating powered toothbrush was assessed in patients rehabilitated with fixed prostheses on implants. One hundred consecutive patients (aged 18-80; mean 56.3; 51 females), who met the inclusion/exclusion criteria and who participated in a regular annual recall scheme, were enrolled. They were instructed on how to use the powered toothbrush, as well as on classical interdental plaque control. The electric toothbrush had to be used twice daily for 2 min. The following periodontal parameters were measured at baseline and at 3 months, 6 months and 12 months: presence/absence of gingival and/or mucosal ulceration/desquamation; sulcus bleeding index; probing pocket depth; periodontal pocket-bleeding index and gingival recession. At 3 months and at the end of the study, patients completed a questionnaire concerning the overall acceptability and convenience of the powered toothbrush, as compared with their habitual manual toothbrush. A total of 80 patients completed the study. No dropouts were related to the use of the powered toothbrush. All parameters improved over the course of the study. The mean overall pocket depth decreased from 3.3 mm at baseline to 3.0 mm at 12 months, while the mean decrease in recession was 0.1 mm at 12 months. During the 1-year observation, there was a slight gain in periodontal attachment level. Gingival ulcerations were not observed at any point in the study. High scores for convenience and comfort of the powered toothbrush were reported, and the majority (95%) said that they would continue to use it for habitual oral hygiene. It is concluded that the powered toothbrush investigated is effective, safe and comfortable for patients rehabilitated by means of oral implant-supported prostheses.

Does excessive occlusal load affect osseointegration? An experimental study in the dog

AIM

The purpose of this study was to evaluate the effect of excessive occlusal load following placement of titanium implants in the presence of healthy peri-implant mucosal tissues.

MATERIALS AND METHODS

Mandibular bilateral recipient sites in six Labrador dogs were established by extracting premolars and molars. After 3 months, two TPS (titanium plasma sprayed) implants and two SLA (sandblasted, large grit, acid etched) implants were placed on each side of the mandible in each dog. Three implants were lost in the initial healing phase, leaving 45 implants for evaluation. Following 6 months of healing, gold crowns were placed on implants on the test side of the mandible. The crowns were in supra-occlusal contact with the opposing teeth in order to create excessive occlusal load. Implants on the control side were not loaded. Plaque control was performed throughout the experimental period. Clinical measurements and standardised radiographs were obtained at baseline and 1, 3 and 8 months after loading. At 8 months, the dogs were killed and histologic analyses were performed.

RESULTS

At 8 months, all implants were osseointegrated. The mean probing depth was 2.5+/-0.3 and 2.6+/-0.3 mm at unloaded and loaded implants, respectively. Radiographically, the mean distance from the implant shoulder to the marginal bone level was 3.6+/-0.4 mm in the control group and 3.7+/-0.2 mm in the test group. Control and test groups were compared using paired non-parametric analyses. There were no statistically significant changes for any of the parameters from baseline to 8 months in the loaded and unloaded implants. Histologic evaluation showed a mean mineralised bone-to-implant contact of 73% in the control implants and 74% in the test implants, with no statistically significant difference between test and control implants.

CONCLUSION

In the presence of peri-implant mucosal health, a period of 8 months of excessive occlusal load on titanium implants did not result in loss of osseointegration or marginal bone loss when compared with non-loaded implants.

Implant Biomechanics in Grafted Sinus: A Finite Element Analysis

This in vitro study investigated the stress distribution in the bone surrounding an implant that is placed in a posterior edentulous maxilla with a sinus graft. The standard threaded implant and anatomy of the crestal cortical bone, cancellous bone, sinus floor cortical bone, and grafted bone were represented in the 3-dimensional finite element models. The thickness of the crestal cortical bone and stiffness of the graft were varied in the models to simulate different clinical scenarios, representing variation in the anatomy and graft quality. Axial and lateral loads were considered and the stresses developed in the supporting structures were analyzed. The finite element models showed different stress patterns associated with helical threads. The von Mises stress distribution indicated that stress was maximal around the top of the implant with varying intensities in both loading cases. The stress was highest in the cortical bone, lower in the grafted bone, and lowest in the cancellous bone. When the stiffness of the grafted bone approximated the cortical bone, axial loading resulted in stress reduction in all the native bone layers; however, lateral loading produced stress reduction in only the cancellous bone. When the stiffness of the graft was less than that of the cancellous bone, the graft assumed a lesser proportion of axial loads. Thus, it caused a concomitant stress increase in all the native bones, whereas this phenomenon was observed in only the cancellous bone with lateral loading. The crestal cortical bone, though receiving the highest intensity stresses, affected the overall stress distribution less than the grafted bone. The stress from the lateral load was up to 11 times higher than that of the axial load around the implant. These findings suggest that the type of loading affects the load distribution more than the variations in bone, and native bone is the primary supporting structure.

The Use of Implantoplasty and Guided Bone Regeneration in the Treatment of Peri-implantitis: Two Case Reports

A variety of treatment modalities have been proposed for the management of peri-implantitis. These are mostly based on empiric experience and use the systemic administration of an antibiotic in conjunction with surgical intervention. To ensure decontamination of the affected implant surface(s), chemical and/or mechanical debridement is used. For textured implant surfaces, detoxification using implantoplasty could also give favorable results when used as part of the procedure. Two cases are reported in which implants developed localized peri-implantitis lesions. Implantoplasty followed by topical tetracycline decontamination was used in conjunction with guided bone regeneration. In both cases, the procedures were effective in arresting disease and regenerating lost bone. These results suggest that the technique holds promise and should be investigated further.

Barrier membrane and bone graft treatments of dehiscence-type defect at existing implant: a case report

Dehiscence-type bony defects may occur after implant application because of microbial action as well as of biomechanical and occlusal overload. The aim of the treatment of a periimplant defect is to arrest the progression of the bone loss and to achieve a maintainable site for the implant. In these situations, barrier membranes and bone graft materials can be used to achieve complete bone healing around dental implants. Bone regeneration is possible in a periimplant bony defect of a functioning implant if the proper surgical technique is utilized and the etiologic cause is eradicated. This study presents the surgical coverage of a periimplant bony defect around an implant that was inserted 7 years ago. The surgical correction was made using a barrier membrane in conjunction with bone graft materials. A follow-up of 6 months seemed to reveal radiographic bone regeneration.

Split-frame implant prosthesis designed to compensate for mandibular flexure: a clinical report

When an edentulous mandible is restored with 4 or more implants connected by a metal bar and retained with screws, mandibular flexure may cause screw loosening and unnecessary stresses and strains on the prosthesis and implants. Separating the prosthesis at the midline can relieve these stresses and strains. This article describes the separation of a hybrid mandibular denture at the midline.

The anterior cantilever in the implant-supported screw-retained mandibular prosthesis

STATEMENT OF PROBLEM

When implants are placed interforaminally in mandibular implant-supported screw-retained prostheses, the most anterior implant is usually positioned lingual to the incisors of the prosthesis. This creates an anterior cantilever with the entire prosthesis acting as a class I lever and possibly placing the anterior implant under alternating tension and compression during function.

PURPOSE

The purpose of this study was to measure the anterior cantilever of randomly chosen patients with restored mandibular implant-supported fixed prostheses, and to establish the proportions of anterior to posterior cantilever lengths relative to the anteroposterior spread.

MATERIAL AND METHODS

Thirteen edentulous patients were recruited from the University of Minnesota's dental implant program. Each patient had been restored with a maxillary complete denture and a mandibular implant-supported screw-retained prosthesis supported by 5 endosseous implants. Each patient had 1 mandibular impression made with irreversible hydrocolloid, which was poured in type III gypsum. A FaroArm precision 3D measuring stylus was used to make multiple-axis (X-Y-Z) measurements (mm) on the casts of the dental implants, of anteroposterior spread, and anterior and posterior cantilevers. Presence or absence of screw loosening was noted using a screwdriver with finger pressure. Data were analyzed using a 1-way analysis of variance to compare prostheses with loose screws to prostheses without loose screws, for each of 3 outcome measures: length of anterior cantilever, length of posterior cantilever, and anteroposterior spread (P<.05).

RESULTS

Mandibular anterior cantilever lengths ranged from 5.5 to 14.4 mm with a mean of 8.78 mm. Combined posterior cantilever lengths ranged from 9.2 to 20.9 mm with a mean of 16.2 mm. Anteroposterior spread ranged from 5.2 to 12.3 mm with a mean of 7.9 mm. From a total of 65 retaining screws, 7 were found to be completely loose. No apparent correlation was found between length of mandibular anterior cantilever and screw loosening (P=.45), although the ratio of posterior cantilever to anteroposterior spread (2:4) was significantly associated with screw loosening (P=.006).

CONCLUSION

Within the limitations of this study, anterior cantilevers in mandibular implant-supported screw-retained prostheses were frequent and appeared to depend on implant placement and prosthesis design. The ratio of anterior to posterior cantilever lengths was approximately 1:2.

Mandibular flexure and stress build-up in mandibular full-arch fixed prostheses supported by osseointegrated implants

The biomechanical effect of mandibular functional flexure on stress build-up in implant-supported fixed restorations is discussed. The relative deformations and stress distributions in six different designs of implant-supported prosthetic systems (six or four implants, with or without distal cantilevers, cross-arch or midline-divided bar into two free-standing bridges) were analysed by a three-dimensional finite element (FE) model of a human edentulous mandible. A significant amount of stress in the more distal implants and the superstructure at the symphysis arises as a consequence of mandible functional flexure. The analysis of the stress distributions generated by the different restorative patterns suggests that a division of the superstructure at the level of the symphysis significantly restores the natural functional flexure of the mandible.

Biomechanical stress in bone surrounding an implant under simulated chewing

The concept of reducing nonaxial loading of dental implants has been widely regarded as the standard procedure. The aim of this study was to reveal the biomechanical stress distribution in supporting bone around an implant and a natural tooth under chewing function. Three-dimensional finite element models of the mandibular first molar and the titanium implant both with the mandible in the molar region were constructed. The directions of displacement constraints were determined according to the angles of the closing pathways of chopping type and grinding type chewing patterns. The tooth model showed smooth stress distribution in the supporting bone with low stress concentration around the neck of the tooth. The implant model showed stress concentration in the supporting bone around the neck of the implant, especially in the buccal area. The grinding type model of the implant showed higher tensile stress concentration than the chopping type model at the lingual neck of the implant. The results of this study suggested the importance of considering occlusion under chewing function for understanding the biomechanics of oral implants.

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.

Dog model for study of supracrestal bone apposition around partially inserted implants

A dog model for study of supracrestal bone growth around partially inserted implants is described. The mandibular premolar teeth (P1, P2, P3 and P4) were extracted on both sides of the mandible in four dogs. At a surgical exposure 12 weeks later, two 10 mm titanium implants were partially inserted on each side, 15 mm apart, in the areas of the P1 and the P3 so that five threads protruded from the bone crest. A titanium mesh was fastened to the coronal aspect of the two fixtures and covered with an ePTFE membrane. Thus, a space for potential bone formation was created between the two implants. The surgical flaps were coronally positioned and secured with vertical mattress sutures. After 12 weeks of healing, biopsy specimens were retrieved and examined histologically. In three of the four dogs under study, the partially inserted implants had integrated and the intended large wound spaces had been created around the noninserted parts of the implants. However, bone was not formed around the protruding implants. Accordingly, this experimental model may prove useful for future studies on the use of various procedures that hypothetically may enhance bone formation.

Influence Of Patient Characteristics On Finnish Dentists’ Decision-Making In Implant Therapy

The purpose of this survey was to evaluate the association of various patient characteristics or possible contraindications with dentists' treatment decisions in oral implantology among general practitioners (GPs) and dental teachers (DTs) in Finland. A questionnaire was mailed to 400 GPs, selected by stratified randomization by gender and main occupation (public vs private sector), and to all full-time DTs (n = 47) representing clinical disciplines other than surgery and orthodontics. The questionnaire included a clinical description of a situation optimal for implant therapy. The same situation was modified with 10 variations (cases) according to patient characteristics or possible contraindications, later classified into three categories: (1) oral factors, (2) medical factors, and (3) personal factors. Respondents were asked whether or not they would recommend implant therapy for each of the cases separately. For all 10 cases, the public sector dentists recommended implant therapy on average for 48%, the private sector dentists for 57% (P < 0.01), and the DTs for 50%. For cases with periodontal pockets or untreated caries lesions, the private sector dentists recommended implant therapy more frequently than did the public sector dentists (27 vs 16%, P = 0.01, 46 vs 26%, P = 0.000, respectively). In the case of a smoking patient, 15% of DTs, but almost half of the GPs, recommended implant therapy (P = 0.002). Because some treatment decisions in implant therapy varied so widely between the dentist groups surveyed, a national database of dental implants would offer an important forum for the sharing of information and evidence among clinicians in various countries.

Peri-implant bone tissue strains in cases of dehiscence: a finite element study

When patients with a narrow alveolar bone ridge are treated with oral implants, a dehiscence can occur. The lack of bony support at the buccal or lingual side of the implant may present an unfavourable situation from a biomechanical point of view. The hypothesis as to whether the presence of dehiscence leads to an increased risk of marginal bone overload was tested by means of the finite element method. Three different situations for a cylindrical oral implant, which was placed in a mandible, were modelled: i) no dehiscence, ii) a dehiscence at the buccal side and iii) dehiscences at the buccal and lingual sides. It was found that the presence of buccal and/or lingual dehiscences led to a marked increase in marginal bone strains at the mesial and distal sides of the implant, thus increasing the risk of bone tissue overload at these locations. Marginal bone strains at the buccal and/or lingual sides, however, did not increase.

Bone level changes proximal to oral implants supporting fixed partial prostheses

The success of oral implant treatment relies on the presence and maintenance of bone adjacent to implants. The monitoring of radiographic bone level changes provides valuable insight into the longevity of oral implants. The purpose of this study was to measure radiographic bone level changes proximal (mesial and distal) to Brånemark System) implants (Nobel Biocare AB, Göteborg, Sweden) supporting fixed partial prostheses. Measurements were used to determine mean bone loss for the first year of loading by the prosthesis and the mean annual bone loss for subsequent years. These results were then compared and contrasted with various characteristics of the individuals, treatment, and treatment outcomes. Fifty-five subjects with 69 fixed partial prostheses supported by 160 implants were followed over a 1 to 12-year period. A mean bone loss of 0.33 mm (SD 0.59) was measured for the first year of loading and a mean annual bone loss of 0.00 mm (SD 0.11) after the first year. The radiographic bone loss calculated for implants at the first year of loading was positively correlated with the mean annual bone loss thereafter. Males, younger individuals and those implants supporting distal extension prostheses lost significantly more bone in the first year of loading. Larger numbers of implants followed for longer periods of time are needed to further explore the effects of various aspects of treatment on bone loss.

Relative effectiveness of powered and manual toothbrushes in elderly patients with implant-supported mandibular overdentures

AIM

The aim of this study was to compare the clinical effectiveness of a powered toothbrush (Braun Oral-B Plaque Remover 3-D) and a manual soft toothbrush (Oral-B Squish-grip brush) for the control of supragingival plaque and soft tissue inflammation around implants supporting mandibular overdentures.

MATERIAL AND METHODS

The study sample involved 40 edentulous subjects, aged 55-80 years, having 2 unsplinted mandibular implants supporting a complete removable overdenture opposed by a maxillary complete denture. In this single-blinded, randomised, cross-over clinical trial, two 6-week experimental phases were separated by a 2-week wash-out period. 2 weeks prior to each experimental phase (pre-entry visits), implant abutments were polished to remove all plaque and a standardised instruction in the use of the toothbrush was given. Modified plaque and bleeding indices were recorded at the start and end of each experimental period. Mean index scores at each phase were analysed using paired t-test, and the mean number of sites showing a change in plaque or mucositis were compared using the Mann-Whitney U-test. Combined data from 2 different implant systems were considered after controlling for implant type.

RESULTS

Only minor changes in plaque and bleeding scores were observed following the two test periods. There were no statistically significant differences between the manual and powered toothbrushes.

CONCLUSION

Manual and powered brushes were found to be of comparable efficacy with regard to improvement in peri-implant bleeding and plaque indices.

A review of guidelines for implant rehabilitation of the edentulous maxilla

This review suggests some guidelines and protocols for treatment of the edentulous maxilla with osseointegrated implants. Evidence-based treatment options are discussed with reference to risk assessment. Developing technologies applicable to diagnosis, clinical procedures, and laboratory techniques are also discussed. Osseointegrated implants are increasingly advocated as a treatment option for maxillary edentulism and in many situations are the treatment of choice.

The causes of early implant bone loss: myth or science?

The success of dental implants is highly dependent on integration between the implant and intraoral hard/soft tissue. Initial breakdown of the implant-tissue interface generally begins at the crestal region in successfully osseointegrated endosteal implants, regardless of surgical approaches (submerged or nonsubmerged). Early crestal bone loss is often observed after the first year of function, followed by minimal bone loss (< or =0.2 mm) annually thereafter. Six plausible etiologic factors are hypothesized, including surgical trauma, occlusal overload, peri-implantitis, microgap, biologic width, and implant crest module. It is the purpose of this article to review and discuss each factor Based upon currently available literature, the reformation of biologic width around dental implants, microgap if placed at or below the bone crest, occlusal overload, and implant crest module may be the most likely causes of early implant bone loss. Furthermore, it is important to note that other contributing factors, such as surgical trauma and penimplantitis, may also play a role in the process of early implant bone loss. Future randomized, well-controlled clinical trials comparing the effect of each plausible factor are needed to clarify the causes of early implant bone loss.