The effect of surface roughening on the success of orthodontic mini-implants: A systematic review and meta-analysis.

INTRODUCTION: Orthodontic mini-implants are a widely accepted treatment modality in orthodontics; however, the failure rate is moderately high. Surface roughening is the golden standard in conventional oral implantology, and this may prove beneficial for orthodontic mini-implants as well. The objective of this systematic review is to assess the effect of surface roughening on the success rate of orthodontic mini-implants in both adolescent and adult patients undergoing orthodontic treatment. METHODS: Randomized studies comparing the success of surface-roughened and smooth, machined-surface orthodontic mini-implants were included. A literature search was conducted for 6 electronic databases (Pubmed/Medline, Embase, Cochrane, CINAHL, Web of Science, and Scopus), Clinical trial registry (https://www. CLINICALTRIALS: gov), and grey literature (Google Scholar). A manual search of the reference lists of included studies was performed. Two authors independently performed the screening, data extraction, risk of bias, and quality assessments. The risk of bias was assessed with the Cochrane risk-of-bias 2.0 Tool. Data were synthesized using a random effect model meta-analysis presented as a forest plot. The certainty in the body of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool. RESULTS: A total of 4226 unique records were screened, and 6 of these were included in the quantitative analysis. Four additional articles were selected for a secondary outcome. A total of 364 orthodontic mini-implants were included in the primary outcome analysis. There was no statistically significant effect of surface roughening on the success of orthodontic mini-implants (odds ratio = 0.63 favoring roughened orthodontic mini-implants; 95% confidence interval, 0.35-1.14). The secondary outcome (ie, the overall failure rate of roughened orthodontic mini-implants) was 6% based on studies with high heterogeneity. Limitations of this study were the risk of bias, study imprecision, and possible publication bias, leading to a very low certainty in the body of evidence. CONCLUSIONS: There is very low-quality evidence that there is no statistically significant effect of surface roughening on the success of orthodontic mini-implants in humans. The overall failure rate of surface-roughened orthodontic mini-implants was 6%. FUNDING: No funding was received for this review. REGISTRATION: This study was preregistered in the Prospective Register of Systematic Reviews (CRD42022371830).

Maxillofacial prosthetic rehabilitation: A survey on the quality of life.

STATEMENT OF PROBLEM: Maxillofacial prostheses, especially those supported by endosseous implants, are regarded as a viable, secure treatment for the reconstruction of facial defects to restore quality of life. The long-term quality of life of patients treated with facial prostheses with different retentive systems is unclear. PURPOSE: The purpose of this clinical study was to assess the long-term quality of life of patients treated with facial prostheses with different retentive systems over a 14-year period at a Dutch oral and maxillofacial surgery unit. MATERIAL AND METHODS: A total of 66 patients with facial prostheses were inventoried and categorized based on anatomic location and type of retention. A 62-item questionnaire was designed to survey the daily prosthetic use, care, quality, durability, longevity, and reliability of retention. Furthermore, issues relating to general satisfaction, self-image, and socialization frequency were addressed. RESULTS: Completed validated questionnaires were returned by 52 patients. Of the prosthetic replacements, 23% (n=12) were orbital, 33% (n=17) nasal, and 44% (n=23) auricular prostheses. The survey showed that a prosthetic reconstruction led to high satisfaction scores with regard to wearing comfort, anatomic fit, color, and anatomic form. A significant difference was shown for implant-retained facial prostheses, which provided enhanced retention and increased ease of placement and removal (Fisher exact test P=.01 and P=.04). Patients with nasal prostheses were less satisfied with the junction of their prostheses to the surrounding soft tissue and more aware of others noticing their prosthetic rehabilitation. Patients with auricular defects were less embarrassed (P=.01) by their prostheses. Although auricular prostheses were less frequently cleaned (P=.01), no significant difference was found in minor soft tissue complications between different anatomic locations and the various retentive systems. CONCLUSIONS: Implant-retained prostheses have advantages over adhesive-retained prostheses in terms of ease of handling. However, improvements in prosthetic material properties, including color stability and durability, are needed to increase the longevity of facial prostheses.

Costs and clinical outcomes of implant placement during ablative surgery and postponed implant placement in curative oral oncology: a five-year retrospective cohort study.

OBJECTIVES: The aim of this study was to compare costs and clinical outcomes of two protocols for implant placement in edentulous oral cancer patients: implant placement during ablative surgery and postponed implant placement. MATERIAL AND METHODS: All edentulous patients who underwent curative tumor surgery between 2007 and 2009 at the Radboud university medical center (Radboudumc) and UMC Utrecht, both in the Netherlands, were included retrospectively. At the Radboudumc, 79 of 98 patients received implants during ablative surgery. At the UMC Utrecht, 18 of 95 patients received implants after a disease-free period of at least 6 months, because satisfying conventional dentures could not be made. Costs, implant details and clinical outcomes were recorded retrospectively up to 5 years after tumor surgery. RESULTS: Individual costs of implant placement were lower in the during-ablative-surgery protocol (€2235 vs. €4152), while implant failure and loading were comparable to the postponed-placement protocol. In the during-ablative-surgery protocol, more patients received implant-retained overdentures (62% vs. 17%) and more patients had functioning dentures (65% vs. 47%), which were placed at an earlier stage (291 vs. 389 days after surgery). Overall costs of the during-ablative-surgery protocol were higher, as more patients received implants and functioning implant-retained dentures, which were more expensive than conventional dentures. CONCLUSIONS: Placing implants during ablative surgery lowered the individual costs of implant placement and led to more patients with functioning dentures, while implant failure and loading were comparable to postponed placement.

Microstructured ß-Tricalcium Phosphate Putty Versus Autologous Bone for Repair of Alveolar Clefts in a Goat Model.

For the first time it was demonstrated that an osteoinductive calcium phosphate-based putty is effective in the restoration of complex maxillofacial defects. In these defects, adequate mechanical confinement by multiple bony walls and osteoconduction from multiple surfaces are usually lacking. This study compares the efficacy of a microstructured beta-tricalcium phosphate (ß-TCP) putty with autologous bone for the repair of alveolar cleft defects. A total of 10 Dutch milk goats were operated on in a split-mouth study design in which two-wall bony alveolar clefts were created and successively repaired with autologous bone (the gold standard) at one side and ß-TCP putty at the other. After 24 weeks of implantation, histomorphometric and micro-computer tomography analyses proved that the ß-TCP putty group showed equal bone quality and volume to clefts reconstructed with autologous bone. In addition, surgical handling of the putty is superior to the use of calcium phosphates in a granular form. Therefore, the results of this study open a clear trajectory for the clinical use of ß-TCP putty in the reconstruction of the alveolar cleft and other challenging two-wall bony defects.

Comparison of different surface modifications for titanium implants installed into the goat iliac crest.

OBJECTIVES: This in vivo study with implants installed in the goat iliac crest was performed to determine whether the biological and mechanical properties of the bone-to-implant interface are influenced by (i) the type of implant anchorage (i.e., mono- vs. bicortical placement), and (ii) the presence of a bioactive hydroxyapatite (HA) or composite HA/bioactive glass (BG) coatings. MATERIALS AND METHODS: A total of 96 titanium (Ti) implants w/- coatings (Ti, Ti-HA & Ti-HABG; n = 8) were mono- or bicortically placed in the iliac crest of eight goats. At installation and after 4 weeks, implant stability was determined using insertion and removal torque testing (ITQ & RTQ). The peri-implant bone response was histologically and histomorphometrically evaluated by means of bone-to-implant contact (BIC%) and bone area (BA%). RESULTS: Monocortical implants demonstrated significantly lower RTQ values in comparison to ITQ values, whereas for bicortical implant placement RTQ and ITQ were similar. Further, mean RTQ values for monocortical implants were significantly lower in comparison to bicortical implants. Histomorphometrical evaluation demonstrated higher BIC% and BA% for bicortical implants compared to monocortical implants. For bicortical implants, BA% in the inner peri-implant region (0-500 µm) was significantly higher compared to the middle (500-1000 µm) and outer (1000-1500 µm) region. Also, a significant correlation was observed for monocortical implants between RTQ and BIC% and BA%. For surface modifications, no significant differences were found in ITQ and RTQ, for neither mono- nor bicortical implants. Histomorphometrically, HABG-coated implants demonstrated significantly higher BIC% compared to GAE surfaces for both mono- and bicortical implants. Bicortical HA-coated implants revealed significant higher BA% in the inner peri-implant region (0-500 µm) in comparison to bicortical GAE implants. CONCLUSIONS: This study demonstrated that bicortical implant placement beneficially affects implant stability during the early phase of osseointegration. A significant correlation between removal torque and bone-to-implant contact and bone area for monocortical implants was observed, but not for bicortical implants. Therefore, histomorphometrical data should be interpreted with caution to predict the biomechanical implant fixation of bone implants over time. Regarding surface modifications, in the present implantation model, the addition of BG to an RF magnetron sputtered HA coating enhanced the biological behavior of the coating compared to grit-blasted/acid-etched implants.

Evaluation of primary and secondary stability of titanium implants using different surgical techniques.

OBJECTIVE: To investigate the influence of different surgical techniques on the primary and secondary implant stability using trabecular bone of goats as an implantation model. MATERIAL AND METHODS: In the iliac crest of eight goats, 48 cylindrical-screw-type implants with a diameter of 4.2 mm (Dyna(®) ; Bergen op Zoom, the Netherlands) were installed, using three different surgical techniques: (i) 5% undersized, using a final drill diameter of 4 mm; (ii) 15% undersized, using a final drill diameter of 3.6 mm; and (iii) 25% undersized, using a final drill diameter of 3.2 mm. Peak insertion torque values were measured by a Digital(®) (MARK-10 Corporation, New York, NY, USA) torque gauge instrument during placement. At 3 weeks after implantation, removal torque was measured. Histomorphometrically, the peri-implant bone volume was measured in three zones; the inner zone (0-500 µm), the middle zone (500-1000 µm) and the outer zone (1000-1500 µm). RESULTS: Evaluation of the obtained data demonstrated no statistically significant difference between different surgical techniques regarding removal torque values. With respect to the percentage peri-implant bone volume (%BV), also no significant difference could be observed between all three applied surgical techniques for both the inner, middle and outer zone. However, irrespective of the surgical technique, it was noticed that the %BV was significantly higher for the inner zone as compared to middle and outer zone (P < 0.05) around the implant. CONCLUSION: At 3 weeks after implant installation, independent of the used undersized surgical technique, the %BV in the inner zone (0-500 µm) peri-implant area was improved due to both condensation of the surrounding bone as also the translocation of host bone particles along the implant surface. Surprisingly, no mechanical beneficial effect of the 25% undersized surgical technique could be observed as compared to the 5% or 15% undersized surgical technique to improve primary or secondary implant stability.

Secondary closure of small- to medium-size palatal defects after ablative surgery: reappraisal of reconstructive techniques.

PURPOSE: Postoncologic reconstruction of the palate represents a major surgical challenge with respect to the thin intraoral and intranasal lining. Current reconstructive methods have ranged from obturative closure of the defect to microsurgical free tissue transfer. The final choice of treatment will be influenced by the size and location of the defect and surgeon experience. The goals of palate repair include optimizing palatal function for speech and eating, and avoiding dehiscence or postoperative fistulas. This study assessed the reliability of locoregional flaps for reconstructing maxillary defects. PATIENTS AND METHODS: The present study described the surgical outcome of locoregional reconstruction of the hard and soft palate of 5 patients who had previously undergone tumor ablative surgery. They ranged in age from 19 to 64 years. None had received postoperative radiotherapy. The resultant surgical defects ranged in size from 2.5 to 12 cm(2). One patient experienced velopharyngeal insufficiency. RESULTS: In all cases, the palate was closed at the first attempt without complications. All flaps survived, and complete closure was obtained in these 4 patients. The patient with the velopharyngeal insufficiency experienced a significant improvement in articulation and swallowing function. CONCLUSIONS: The results of these 5 cases indicate that secondary locoregional flaps are a suitable alternative for palatal defect management. They have a high success rate and functional outcome. These secondary techniques can be reliably used to reconstruct small- to moderate-size palatal defects and represent a reliable reconstructive option with minimal morbidity.

Tissue engineering strategies for alveolar cleft reconstruction: a systematic review of the literature.

OBJECTIVES: To date, a great number of tissue engineering strategies have been suggested for alveolar cleft reconstruction; however, autologous bone grafting seems to remain the golden standard. MATERIALS AND METHODS: A systematic review of the literature was conducted in order to evaluate the clinical evidence pertaining to enhancement or replacement of the autologous bone graft in the alveolar cleft by means of tissue-engineered substitutes; 16 articles were selected for analysis. RESULTS: Tissue engineering strategies for alveolar cleft grafting included enhancing the autologous bone graft by means of platelet-rich plasma addition, the use of barrier membranes and fibrin glue, extension of the autologous graft with calcium phosphate scaffolds, and replacement of the graft using bone morphogenetic protein-2, mesenchymal stem cells, or calcium phosphate scaffolds. CONCLUSIONS: Selected articles showed a vast heterogeneity in data acquisition and patient selection. Therefore, a meta-analysis could not be performed. Future publications concerning this topic should be methodologically sound and preferably use three-dimensional radiological imaging for pre- and postoperative results. CLINICAL RELEVANCE: Bypassing or enhancing autologous bone grafting by means of tissue engineering solutions has become an important topic in alveolar cleft grafting. Replacement of the autologous bone graft will result in absence of donor site morbidity in this predominantly young population.

A clinically relevant validation method for implant placement after virtual planning.

PURPOSE: To design a relevant method to compare the virtual planned implant position to the ultimately achieved implant position and to evaluate, in case of discrepancy, the cause for this. MATERIALS AND METHODS: Five consecutive edentulous patients with retention problems of the upper denture received four implants in the maxilla. Preoperatively, first a cone-beam CT (CBCT) scan was acquired, followed by virtual implant planning. Then, a surgical template was designed and endosseous implants were flapless installed using the template as a guide. To inventory any differences in position, the postoperative CBCT scan was matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally (3D) and the Implant Position Orthogonal Projection (IPOP) validation method was applied to project the results to a bucco-lingual and mesio-distal plane. Subsequently, errors introduced by virtual planning, surgical instruments, and validation process were evaluated. RESULTS: The bucco-lingual deviations were less obvious than mesio-distal deviations. A maximum linear tip deviation of 2.84 mm, shoulder deviation of 2.42 mm, and angular deviation of 3.41° were calculated in mesio-distal direction. Deviations included errors in planning software (maximum 0.15 mm), for surgical procedure (maximum 2.94°), and validation process (maximum 0.10 mm). CONCLUSIONS: This study provides the IPOP validation method as an accurate method to evaluate implant positions and to elucidate inaccuracies in virtual implant planning systems.

Maxillary sinus floor augmentation with injectable calcium phosphate cements: a pre-clinical study in sheep.

OBJECTIVES: The aim of this pre-clinical study was to evaluate the biological performance of two injectable calcium phosphate cement (CPC) composite materials containing poly(D,L-lactic-co-glycolic)acid (PLGA) microspheres with different properties in a maxillary sinus floor elevation model in sheep. MATERIALS AND METHODS: PLGA microspheres were made of either low molecular weight (~17 kDa) acid-terminated PLGA (PLGA(L-AT) ) or high molecular weight (~44 kDa) end-capped PLGA (PLGA(H-EC) ) and incorporated in CPC. Eight female Swifter sheep underwent a bilateral maxillary sinus floor elevation procedure via an extra-oral approach. All animals received both materials, alternately injected in the left and right sinus (split-mouth model) and a time point of 12 weeks was used. Analysis of biological performance was based on histology, histomorphometry, and evaluation of sequential fluorochrome labeling. RESULTS: Both types of CPC-PLGA composites showed biocompatibility and direct bone-cement contact. CPC-PLGA(L-AT) showed a significantly higher degradation distance compared to CPC-PLGA(H-EC) (1949 ± 1295 µm vs. 459 ± 267 µm; P = 0.0107). Further, CPC-PLGA(L-AT) showed significantly more bone in the region of interest (26.4 ± 10.5% vs. 8.6 ± 3.9% for PLGA(H-EC) ; P = 0.0009) and significantly less remaining CPC material (61.2 ± 17.7% vs. 81.9 ± 10.9% for PLGA(H-EC) ; P = 0.0192). CONCLUSIONS: Both CPC-PLGA(L-AT) and CPC-PLGA(H-EC) demonstrated to be safe materials for sinus floor elevation procedures in a large animal model, presenting biocompatibility and direct bone contact. In view of material performance, CPC-PLGA(L-AT) showed significantly faster degradation and a significantly higher amount of newly formed bone compared to CPC-PLGA(H-EC) .

Long-term survival of calcium phosphate-coated dental implants: a meta-analytical approach to the clinical literature.

BACKGROUND: Calcium phosphate ceramic coatings have the potential to compensate for challenging bone conditions such as delayed or impaired bone healing and low bone quantity or density. Thus, the increasing universal prevalence of subjects with such challenging bone conditions might be paralleled by an enhanced global use of calcium phosphate ceramic-coated dental implants. However, it is speculated that the long-term clinical survival of calcium phosphate-coated dental implants might be adversely affected by coating delamination. OBJECTIVE: The aims of the current review were (1) to systematically appraise and (2) to meta-analyse long-term survival data of calcium phosphate-coated dental implants in clinical trials. MATERIALS AND METHODS: An extensive search in the electronic databases of the National Library of Medicine (http://www.ncbi.nlm.nih.gov), The Cochrane Central Register of Controlled Trials and the ISI Web of Knowledge, was carried out for articles published between January 2000 and November 2011 to identify randomized controlled clinical trials, prospective clinical trials as well as retrospective analysis of cases (RA) presenting survival data on the topic of calcium phosphate-coated dental implants. Only publications in English were considered, and the search was narrowed to studies in humans with a follow-up of at least 5 years only. Furthermore, the reference lists of related review articles and publications selected for inclusion in this review were systematically screened. The primary outcome variable was percentage annual failure rate (AFR), and the secondary outcome variable was percentage cumulative survival rate (CSR). RESULTS: The electronic search in the database of the National Library of Medicine, The Cochrane Central Register of Controlled Trials and the ISI Web of Knowledge, resulted in the identification of 385 titles. These titles were initially screened by the two independent reviewers for possible inclusion, resulting in 29 publications suitable for further consideration. Screening the abstracts led to 20 full-text articles. From these articles, 15 reports were excluded. Finally, five of these original research reports could be selected for evaluation. No additional publications were identified by manual search. Thus, a total of five articles were included for analysis. Meta-analysis revealed that neither AFRs of calcium phosphate-coated dental implants increased progressively nor that long-term CSRs for calcium phosphate-coated dental implants were inferior to survival rates of noncoated implants. CONCLUSION: We conclude that (1) published long-term survival data for calcium phosphate-coated dental implants are very limited, (2) AFRs of calcium phosphate-coated dental implants do not increase progressively, and (3) long-term CSRs for calcium phosphate-coated dental implants are comparable to survival rates of noncoated implants.

Regeneration of the periodontium using enamel matrix derivative in combination with an injectable bone cement.

OBJECTIVES: Enamel matrix derivative (EMD) has proven to enhance periodontal regeneration; however, its effect is mainly restricted to the soft periodontal tissues. Therefore, to stimulate not only the soft tissues, but also the hard tissues, in this study EMD is combined with an injectable calcium phosphate cement (CaP; bone graft material). The aim was to evaluate histologically the healing of a macroporous CaP in combination with EMD. MATERIALS AND METHODS: Intrabony, three-wall periodontal defects (2 × 2 × 1.7 mm) were created mesial of the first upper molar in 15 rats (30 defects). Defects were randomly treated according to one of the three following strategies: EMD, calcium phosphate cement and EMD, or left empty. The animals were killed after 12 weeks, and retrieved samples were processed for histology and histomorphometry. RESULTS: Empty defects showed a reparative type of healing without periodontal ligament or bone regeneration. As measured with on a histological grading scale for periodontal regeneration, the experimental groups (EMD and CaP/EMD) scored equally, both threefold higher compared with empty defects. However, most bone formation was measured in the CaP/EMD group; addition of CAP to EMD significantly enhanced bone formation with 50 % compared with EMD alone. CONCLUSIONS: Within the limits of this animal study, the adjunctive use of EMD in combination with an injectable cement, although it did not affect epithelial downgrowth, appeared to be a promising treatment modality for regeneration of bone and ligament tissues in the periodontium. CLINICAL RELEVANCE: The adjunctive use of EMD in combination with an injectable cement appears to be a promising treatment modality for regeneration of the bone and ligament tissues in the periodontium.

Soft tissue response to zirconia and titanium implant abutments: an in vivo within-subject comparison.

AIM: To compare the health of the soft tissues towards zirconia and titanium abutments in man, as observed using histological data. MATERIAL AND METHODS: Twenty patients received two mandibular implants with either a zirconia or titanium abutment (split mouth study design, left-right randomization). After 3 months soft tissue biopsies were prepared for histological evaluation. They were subjected to blind evaluation. The number of blood vessels per surface unit and an inflammation grading scale score ranging from 1 to 4 were determined. RESULTS: Paired samples from 17 patients were suitable for analysis, 3 with unsevered implant-abutment connections and 14 solely containing soft tissue. All showed a well-keratinized stratified squamous epithelium which was continuous with the barrier (junctional) epithelium that faced the abutment surface. The normal epithelial build-up could be recognized with little signs of inflammation. No statistically significant difference in tissues adjacent to zirconia and titanium abutment surfaces were seen with respect to vascular density (20.5 SD 4.4 and 20.7 SD 3.2) or inflammation grading scale scores (3.2 SD 0.7 versus 3.1 SD 0.7). CONCLUSION: No differences in soft tissue health were seen in peri-implant mucosa adjacent to zirconia and titanium abutment surfaces.

Alkaline phosphatase immobilization onto Bio-Gide® and Bio-Oss® for periodontal and bone regeneration.

AIM: To evaluate the effect of alkaline phosphatase (ALP) immobilization onto Bio-Gide(®) in vitro, and to study the in vivo performance of ALP-enriched Bio-Gide(®) and/or Bio-Oss(®) with the purpose to enhance periodontal regeneration. MATERIALS AND METHODS: Alkaline phosphatase ALP was immobilized onto Bio-Gide(®) and Bio-Oss(®) . Forty-eight rats received periodontal defects, which were treated according to one of the following strategies: Bio-Gide(®), Bio-Gide(®) -ALP, Bio-Gide(®) -ALP/Bio-Oss(®), Bio-Gide(®) /Bio-Oss(®) -ALP, Bio-Gide(®) -ALP/Bio-Oss(®) -ALP, or empty. Micro-CT and histological analysis were performed. RESULTS: A 30 min ALP-deposition time was determined as optimal from mineralization capacity assessment and consequently used as Bio-Gide(®) -ALP membranes in the animal experiment. In vivo results showed that after 2 weeks, the defect and implanted materials were still visible, an inflammatory response was present, and membrane degradation was ongoing. Bone formation, although limited, was observed in the majority of Bio-Gide(®) -ALP specimens and all of the Bio-Gide(®) /Bio-Oss(®) -ALP specimens, and was significantly higher compared with Bio-Gide(®) and empty controls. After 6 weeks, the defects and particles were still visible, whereas membranes were completely degraded. The inflammatory response was decreased and bone formation appeared superior for Bio-Gide(®) -ALP treated defects. CONCLUSION: Immobilization of ALP onto guided tissue regeneration (GTR)/ guided bone regeneration (GBR)-materials (Bio-Gide(®) and Bio-Oss(®)) can enhance the performance of these materials in GTR/GBR procedures.

Biological limits of the undersized surgical technique: a study in goats.

OBJECTIVE: The purpose of the present study was to investigate the influence of different implant placement techniques on the early bone healing response in an animal model. MATERIAL AND METHODS: In the present study, 24 cylindrical-screw-type implants with a diameter of 4.2 mm (Dyna®) were installed, using three different surgical techniques; (1) 5% undersized, using a final drill diameter of 4 mm; (2) 15% undersized, using a final drill diameter of 3.6 mm; and (3) 25% undersized, using a final drill diameter of 3.2 mm. After 3 weeks of implantation period, the peri-implant bone response was histologically evaluated and the percentage of bone-implant contact (%BIC) calculated. RESULTS: New bone formation was more pronounced for implants placed with the 5% undersized or 15% undersized technique, as compared with implants installed with the 25% undersized technique. Histomorphometrical data corroborates these findings as the %BIC was significantly higher for implants inserted with the 5% undersized (47.7 ± 11.1) or 15% undersized protocol (47.5 ± 9.5) as compared with implants inserted with the 25% undersized technique (32.1 ± 9.7). No significant difference in %BIC could be observed between the 5% undersized and 15% undersized installed implants. CONCLUSION: Within the limitation of the present study, it was concluded that excessive compression of the host bone, when a discrepancy between implant and final drill diameter more than 15%, can result in an inferior tissue response in the early stage of healing. To compare research results in the future, it is advised to specify the term "undersized" by mentioning the real reduction in diameter.

Combined effect of undersized surgical technique and axial compression on the primary implant stability and host bone architecture.

AIM: The aim of this study was to investigate the combined effect of the lateral-compression of host-bone (undersized-osteotomy-preparation) and axial-compression of host-bone (not drilling the full length of the implant) on the primary-implant-stability and the host-bone-architecture. MATERIALS AND METHODS: In this experimental-study, 44 dental implants (diameter-4.2 mm; length-10 mm; Dyna®) were installed in the femoral-condyles of four cadaver-goats using four different surgical approaches (11 implant/surgical approach; n = 11). Approach-1: Standard preparation according to the manufacturer's guidelines. The bone-cavity was prepared up to 10 mm in depth and 4 mm in diameter. Approach-2: Preparation up to 8 mm in depth and 4 mm in diameter. Approach-3: Preparation up to 10 mm in depth. Approach-4: The bone-cavity was prepared up to 8 mm in depth and 3.6 mm in diameter. Insertion torque (n = 11), removal torque (n = 7) and % bone-implant contact (n = 4) measurements were recorded. Bone architecture was assessed by micro-computer tomography and histological analysis (n = 4). RESULTS: For approaches 2, 3, and 4 (P < .05), insertion-torque values were significantly higher as compared to approach 1. Regarding the bone-implant-contact percentage (%BIC), approach 3 and 4 were significantly higher compared to approach 1 and 2 (P<.05). For approach 2, the %bone volume (%BV) was significantly higher as compared to approach 1 (P<.05) for the most the inner zone of host bone in proximity of the implant. CONCLUSION: Lateral and axial compression improved the primary-implant-stability and therefore this new surgical-technique should be considered as an alternative approach especially for placing implants in low-density bone. Nevertheless, additional in vivo studies should be performed.

Influence of surgical technique and surface roughness on the primary stability of an implant in artificial bone with different cortical thickness: a laboratory study.

OBJECTIVE: The aim of this biomechanical study was to assess the interrelated effect of both surface roughness and surgical technique on the primary stability of dental implants. MATERIAL AND METHODS: For the experiment, 160 screw-designed implants (Biocomp), with either a machined or an etched surface topography, were inserted into polyurethane foam blocks (Sawbones). As an equivalent of trabecular bone, a density of 0.48 g/cm(3) was chosen. To mimic the cortical layer, on top of these blocks short-fibre-filled epoxy sheets were attached with a thickness varying from 0 to 2.5 mm. The implant sites were prepared using either a press-fit or an undersized technique. To measure the primary stability of the implant, both the insertion and the removal torques were scored. RESULTS: Independent of the surgical technique used, both implant types showed an increased insertion and removal torque values with increasing cortical thickness, although >2 mm cortical layer no further increase in insertion torque was observed. In the models with only trabecular bone (without cortical layer) and with a 1 mm cortical layer, both implant types showed a statistically higher insertion and removal torque values for undersized compared with the press-fit technique. In addition, etched implants showed a statistically higher insertion and removal torque mean values compared with machined implants. In the models with 2 and 2.5 mm cortical layers, with respect to the insertion torque values, no effect of either implantation technique or implant surface topography could be observed. CONCLUSION: The placement of etched implants in synthetic bone models using an undersized preparation technique resulted in enhanced primary implant stability. A correlation was found between the primary stability and the cortical thickness. However, at or above a cortical thickness of 2 mm, the effect of both an undersized surgical approach, as also the presence of a roughened (etched) implant surface, had no extra effect. Besides the mechanical aspects, the biological effect of undersized drilling, i.e. the bone response on the extra insertion torque forces should also be elucidated. Therefore, additional in vivo studies are needed.

Reproducibility of 3 different tracing methods based on cone beam computed tomography in determining the anatomical position of the mandibular canal.

PURPOSE: To investigate the reproducibility of 3 different tracing methods to determine a reliable method to define the proper anatomical position of the mandibular canal based on cone beam computed tomography (CBCT) data. MATERIALS AND METHODS: Five dentate and 5 edentate patients were selected at random from the CBCT database. Two independent observers traced both the left and the right mandibular canal using 3-dimensional image-based planning software (Procera System NobelGuide; Nobel Biocare, Göteborg, Sweden). All mandibular canals were traced using 3 different methods. Method I was based on coronal views, also known as cross-sections. Panorama-like reconstructions were the starting point for method II. The third method combined methods I and II. RESULTS: With respect to interobserver reliability, no significant difference (P = .34) for the various methods was observed. The reproducibility was better in edentate than in dentate jaws (P = .0015). The difference between 2 tracings was the lowest for the combined method: within a range of 1.3 mm in 95% of the course of the canal. The most obvious deviations were mainly seen in the anterior part of the canal. CONCLUSIONS: The best reproducible method for mandibular canal tracing is the combined method III. Between observers, still a mean 95th percentile deviation threshold of 1.3 mm (SD 0.384) is noted, indicating that a safety zone of 1.7 mm should be respected. When planning surgery on CBCT-based data, surgeons should be aware of the obvious deviations located in the region of the anterior loop of the canal.

Influence of the surgical technique and surface roughness on the primary stability of an implant in artificial bone with a density equivalent to maxillary bone: a laboratory study.

OBJECTIVE: The aim of this biomechanical study was to assess the effect of surgical technique and surface roughness on primary implant stability in low-density bone. MATERIAL AND METHODS: Eighty screw-shaped (Biocomp) implants with machined or etched surface topography were inserted into a low-density bone equivalent. Solid rigid polyurethane blocks (Sawbones) with two different bone densities (group A=0.32 g/cm(3); group B=0.48 g/cm(3)) were used that are very similar to the density of the maxilla. The implant sites were prepared either by a press-fit or by an undersized technique. Peak insertion and removal torques were measured using a Digital torque gauge instrument. RESULTS: Independent of the surgical technique used, both implant types showed an increased mean insertion and removal torque value with increasing bone density. Insertion and removal torque values were 54.3+/-5.3 and 43.5+/-6.5 N cm for group A and 89.3+/-7.6 and 55+/-9.1 for group B, respectively. For group A and B, both implant types showed statistically higher insertion and removal torque mean values for the undersized compared with the press-fit technique (P<0.01). In addition, etched implants showed statistically higher insertion and removal torque mean values compared with machined implants (P<0.01). CONCLUSION: The placement of etched implants in synthetic bone models using an undersized preparation technique resulted in enhanced primary implant stability; further, a correlation was found between primary stability and bone density of the synthetic bone, implying that in case of an implant site with low bone density, by changing the surgical technique and choosing an implant with an optimal surface roughness, the primary stability can be enhanced significantly.

Assessment of bone vascularity in the anterior mandible using laser Doppler flowmetry.

OBJECTIVES: In irradiated bone, a method assessing vascularity of intended implant recipient bone would be of clinical significance in preventing early implant loss and in reducing the risk of osteoradionecrosis due to surgical oral implant insertion. At present, assessing bone vascularity clinically, using laser Doppler flowmetry (LDF), seems to be realistic. The hypotheses of this study were that bone vascularity in the human anterior mandible can be assessed during implant insertion by LDF and that the recorded LDF values are providing standard data for bone vascularity in the human anterior mandible. MATERIAL AND METHODS: Twenty-three randomly selected non-irradiated edentulous patients scheduled for treatment with oral implants in the anterior mandible were assigned, 12 men and 11 women. The patients' history of edentulousness and resorption of the residual alveolar ridges were registered. In pilot osteotomy sites of planned implant insertion, the bone vascularity was registered, using LDF and expressed in perfusion units (PU). The statistical distribution and characteristics of the LDF values were explored, separately for men and women. RESULTS: A total of 41 pilot osteotomy sites were recorded with a mean LDF value of 25.80 PU. No obvious gender difference was found and LDF values did not show a relationship with patient's age or history of edentulousness. CONCLUSION: The hypotheses that bone vascularity in the human anterior mandible can be assessed during implant insertion by LDF and that the recorded LDF values are providing standard data for bone vascularity in the human anterior mandible, were confirmed.