HGF/MET in osteogenic differentiation of primary human palatal periosteum-derived mesenchymal stem cells.

PURPOSE: This study aimed to determine expressions of hepatocyte growth factor (HGF) and MET proto-oncogene receptor tyrosine kinase (MET) in palatal periosteum (PP) and to examine the effect of HGF/MET on osteogenic differentiation of human palatal periosteum-derived mesenchymal stem cells (PD-MSCs). METHODS: HGF/MET proteins in human palatal periosteum (n = 3) were localized using immunohistochemistry. PD-MSCs (n = 3) were cultured in serum-free Essential 8 (E8) medium or osteogenic medium with and without Capmatinib, a selective ATP-inhibitor of MET. HGF concentration in vitro was measured with ELISA. Relative gene expression was quantified from PD-MSCs by quantitative reverse transcription real-time polymerase chain reaction. RESULTS: Immunohistochemistry detected co-localization of HGF and MET protein in PP. HGF protein levels were significantly higher (P < 0.05) in osteogenic media (day 21: 12.19 ± 8.36 ng/mL) than in E8 medium (day 21: 0.42 ± 0.72 ng/mL). MET inhibitor had a limited feedback effect on the expression profile of the osteogenic genes tested. Gene expression levels for all but three genes were comparable in serum-free and osteogenic media at all time points. CONCLUSION: HGF/MET present in human PP and HGF is upregulated in vitro during osteogenesis; however the targeted pathways controlled by MET may not involve osteoblast maturation.

Multicentre prospective evaluation of implant-assisted mandibular removable partial dentures: surgical and prosthodontic outcomes.

OBJECTIVE: To determine implant survival and prosthodontic maintenance of implant-assisted mandibular removable partial dentures in a multicentre prospective study up to 10 years. MATERIALS AND METHODS: Forty-eight participants with mandibular distal extension partial dentures were selected. A control group of 12 New Zealand participants had new conventional mandibular partial dentures made. Three test groups of 36 participants in New Zealand (n = 12), the Netherlands (n = 12) and Colombia (n = 12) had bilateral distal implants placed. Surgical and prosthodontic outcomes were documented with only healing caps placed (Stage 1) and with an attachment system (Stage 2). RESULTS: No implants failed after 3 years. Four late implant failures in three participants occurred in New Zealand (two unilateral implant failures after 5 and 8 years and two bilateral implant failures in the same participant after 6 and 10 years); two unilateral late implant failures occurred in the Netherlands and no late failures in Colombia. Implant survival rate was 92% by 10 years. Resonance frequency measurements were taken at surgery implant stability quotient (ISQ) 62.44 ± 7.46; range 40 - 79), baseline (ISQ 63.22 ± 6.17; range 50 - 74) and after 3 years (ISQ 66.38 ± 6.77; range 55 - 83). In New Zealand and Colombia, measured crestal bone levels were 2.03 ± 0.71 mm and 2.20 ± 0.81 mm, respectively, at baseline and 3 years. For Stage I, principal prosthodontic maintenance issues were loose healing caps among 10 New Zealand participants, four Colombian participants and one Netherlands participant. For Stage 2, matrix activation and overdenture puncture fractures resulted in 41 events (25 participants) in New Zealand over 10 years, whilst over 3 years, there were 14 events in nine Colombian participants and six events in five Netherlands participants. CONCLUSION: This clinical multicentre research complements previous case reports, case series, retrospective and prospective studies on the notion of implant-assisted removable partial dentures for partially edentulous patients. Late implant failures and increased prosthodontic maintenance when an attachment system is used identify the need for further research, including more robust statistical analyses.

Maxillary Three-Implant Overdentures Opposing Mandibular Two-Implant Overdentures: 10-Year Surgical Outcomes of a Randomized Controlled Trial.

BACKGROUND: The surgical placement of four maxillary implants for overdentures may not be obligatory when opposing mandibular two-implant overdentures. PURPOSE: To determine 10-year surgical outcomes and implant success of three narrow diameter implants in edentulous maxillae with conventional loading. MATERIALS AND METHODS: Forty participants with mandibular two-implant overdentures were randomly allocated for surgery for maxillary overdentures. Using osteotomes, three implants of similar systems were placed with a one-stage procedure and 12-week loading with splinted and unsplinted prosthodontic designs. Marginal bone and stability measurements were done at surgery, 12 weeks, 1-, 2-, 5-, 7-, 10 years. RESULTS: One hundred seventeen implants were placed in 39 participants, with 35 being seen at 1 year; 29 at 2 years; 28 at 5 years; 26 at 7 years; and 23 (59%) at 10 years. Marginal bone loss was 1.35 mm between surgery and 12 weeks; 0.36 mm between 12 weeks and 1 year; 0.48 mm between 1 and 5 years; and 0.22 mm between 5 and 10 years. Implant stability quotients were 56.05, 57.54, 60.88, 58.80, 61.17 at surgery, 12 weeks, 1 year, 5 years, and 10 years. Four-field tables by implant showed success rates of 82% at 1 year; 69.2% at 2 years; 66.7% at 5 years; 61.5% at 7 years; 51.3% at 10 years. Data showed no differences between surgical technique, systems, or prosthodontic designs. CONCLUSIONS: Surgical placement with osteotomes of three narrow diameter implants for maxillary overdentures, opposing mandibular two-implant overdentures, is an acceptable approach, subject to strict patient selection. Implant success is independent of prosthodontic design.

Could the median-palate accommodate wide-bodied implants in order to support maxillary over-dentures? A radiomorphometric study of human cadavers.

INTRODUCTION: Atrophy of the alveolar bone is an irreversible multifactorial phenomenon, the rate of which varies between individuals and between the jaws. This atrophy of the alveolar ridges presents severe limitations for the oral rehabilitation of the edentulous patients and poses a clinical challenge to the prosthodontists and implant surgeons. The present research aimed to investigate whether the median-palate of elderly edentulous subjects is anatomically suitable for implant placement. MATERIALS AND METHODS: A total of 32 samples were harvested from the maxillae of 16 human cadavers. One dentate male subject was included for contrast. Bone quality and quantity were analysed at two regions: the median-palate and the edentulous maxillary alveolar ridge. Samples were scanned through micro-CT, and the region of analysis (ROA) identified and dissected. Bone volume to tissue volume ratio (%BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp) and trabecular bone pattern factor (Tb.Pf) were evaluated for the two regions using Skyscan CTAn(®). RESULTS: The results of bone volume fraction obtained from CTAn(®) of the median-palatal region show higher values than the respective premolar sites in 12 of 15 (80%) edentulous samples. However, this difference was statistically non-significant (P = 0.06). Similarly, the trabecular number for 10 of 15 samples (66.6%) from the median-palate shows greater values than the respective premolar site (P = 0.07). Trabecular thickness of 10 of 15 (66.6%) premolar samples is larger than in the median-palatal region. However, these differences were also statistically non-significant (P = 0.25). Statistically significant difference (P = 0.04) was found between the Tb.Sp values of the two regions. CONCLUSION: The results indicate that the anterior median-palate is structurally better than their respective maxillary premolar region in elderly edentulous persons, and an implant can be placed to anchor an overdenture. The best site for a wide-body implant was established to be 6-8 mm posterior to the incisive foramen in elderly edentulous patients.

The prognostic accuracy of resonance frequency analysis in predicting failure risk of immediately restored implants.

OBJECTIVES: It is of imperative clinical significance to define a safe threshold for planned immediate implant restoration. The aim of this report was to evaluate the prognostic accuracy of resonance frequency analysis (RFA) measurements recorded at two different times (implant placement and 8-week post-implant placement) and to determine the optimal threshold value for predicting failure risk of immediately restored/loaded implants. MATERIAL AND METHODS: Twenty-eight 8- or 9-mm-diameter implants were placed in either a fresh molar extraction socket or a healed site. An electronic RFA device was used to record the implant stability quotients (ISQs) at implant placement surgery, 8 weeks and 1 year. Receiver operating characteristic (ROC) analysis was used to identify the optimal cut-off level. Sensitivity and specificity were also determined at the selected cut-off value. RESULTS: The area under the ROC curve for RFA at 8 weeks was 0.93 with a significant P-value (P = 0.001). The optimum cut-off value for detecting implant stability was 60.5 ISQ measured at 8 weeks, with sensitivity and specificity of 95.2% and 71.4%, respectively. CONCLUSIONS: The implant stability measurements after 8 weeks showed a better accuracy in predicting implants that were at risk of failure than those taken at the time of implant placement.

Trabecular bone microarchitecture in the median palate and maxillary premolar alveolar sites of edentulous elderly cadavers.

PURPOSE: The median palate has been proposed as an alternative site for implant placement supporting maxillary overdentures. The aim of our research was to compare the histologic bone microarchitecture of the median palatal and the maxillary premolar alveolar ridge in edentulous elderly human cadavers. MATERIALS AND METHODS: The bone quality and quantity were analyzed at two regions of analysis (ROA) in 16 maxilla of human cadavers: the median palate (ROA I) and edentulous maxillary alveolar premolar ridge (ROA II). Histomorphometry of the scanned images was performed using image analysis software (National Institutes of Health ImageJ). The bone volume/tissue volume ratio, trabecular thickness, trabecular separation, and trabecular number were evaluated for the two regions. RESULTS: The bone volume fraction of the median-palatal region (ROA I) was greater than at the respective premolar sites (ROA II) in 10 of 15 samples (66.6%), with mean values ranging from 19.3-61.3%. However, the results were not statistically significant (P = .151). Similarly, the trabecular number of ROA II showed greater values than that for ROA II (mean TbN for ROA I, 1.03 mm(-1) and for ROA II, 0.96 mm(-1)). However, these differences were not statistically significant (P = .454). CONCLUSIONS: These results have indicated that the anterior median palate is structurally similar to the corresponding maxillary premolar region in elderly edentulous persons. Therefore, it can be used as an implant site to anchor a maxillary overdenture in patients with atrophic maxillary ridges.

The thickness of parietal bones in a new zealand sample of cadaveric skulls in relation to calvarial bone graft.

Objectives To evaluate the average thickness of the parietal bones in their different regions to identify the ideal site(s) for calvarial bone graft harvest. Methods and Materials Thickness of the parietal bones of 25 wet cranial vaults of New Zealand European origin was measured in 135 different locations using an electronic caliper. Analyses to identify the ideal harvest sites were conducted so that the sites fit the features of an ideal harvest site described in the literature as: (1) 6 mm of minimum thickness and (2) 2 cm away from the midline. Results and Conclusion The overall average thickness was 6.69 ± 0.22 mm. The average thickness at different sites within the same bone ranged from 2.85 to 6.93 mm. In keeping with previous studies, the report observed a progressive thickening of the parietal bone in medial and posterior directions. Of the 135 different locations measured, only 20% exceeded an average thickness of 6 mm as well as being 2 cm away from the sagittal midline. These locations were mainly located between 6 to 11 cm posterior to the coronal suture and 2 to 5 cm away from the sagittal suture. Conclusion Harvesting the calvarial bone graft in the area 6 to 11 cm posterior to the coronal suture and 2 cm away from the midline is recommended based on our study using cadaveric cranial vaults of New Zealand Europeans.

Fractured zirconia implants and related implant designs: scanning electron microscopy analysis.

OBJECTIVES: Two fractured one-piece experimental (commercially unavailable) zirconia implants were analyzed using scanning electron microscope (SEM) analysis to identify failure origins and aid in understanding the failure mechanisms. Modifications to the zirconia implant design are suggested to minimize such fracture incidences. MATERIALS AND METHODS: Two zirconia implants fractured during the final torquing in the maxillary ridge using the prescribed hand torque wrench. The implants were subsequently retrieved and prepared for optical and SEM evaluation. Critical attention was given to the fractography (crack morphology) of the fractured implants to identify the fracture origin. RESULTS: Events related to initiation and propagation of the crack front could be detected from the morphology of the fractured surfaces. Unfavorable torque and bending forces applied on the implant during surgical placement and the inherent flaws in the material may have resulted in crack initiation and implant failure. CONCLUSIONS: Caution must be exercised when placing zirconia implants in dense bone sites. Modification of surgical protocols for the intended implant site may be necessary. Improvement in design features specific to zirconia implants, and strict quality control during manufacture is essential to minimize the likelihood of fracture.

Immediate single implant restorations in mandibular molar extraction sockets: a controlled clinical trial.

BACKGROUND: In the replacement of missing teeth, a paradigm shift is currently observed with immediate implant placement and/or restoration, particularly in the aesthetic zone. In molar sites, however, anatomical, occlusal and biomechanical considerations remain deterrent factors influencing the outcome of this treatment paradigm. The aim of this report was to evaluate immediate placement and immediate restoration of strongly tapered wide-diameter implant in fresh mandibular molar extraction sockets. METHODS: Twenty-four 8- or 9-mm diameter implants were placed in either a fresh molar extraction socket or a healed site. All the implants received provisional crowns within 48 h. The provisional crowns were replaced with full ceramic crowns after 8 weeks of implant placement. RESULTS: The overall implant success rate after 1 year of service for the 24 implants in two treatment groups was 75%. Success rates were 83.3% and 66.7% for the delayed and immediate placement groups respectively, with no significant difference observed between the two groups (P = 0.35). Implant stability measurements identified the immediately placed implants to be more stable immediately after surgery than delayed placed implants. In contrast, the delayed placed implants were more stable after 8 week healing time. CONCLUSIONS: The rehabilitation of single missing mandibular molars by immediately placed and restored wide-diameter implants was associated with a relatively high failure rate.

Mandibular single-implant overdentures: preliminary results of a randomised-control trial on early loading with different implant diameters and attachment systems.

OBJECTIVES: To determine surgical and prosthodontic outcomes of mandibular single-implant overdentures, opposing complete maxillary dentures, using a wide diameter implant and large ball attachment system compared with different regular diameter implants with standard attachment systems. MATERIALS AND METHODS: Thirty-six edentulous participants (mean age 68 years, SD 9.2) were randomly assigned into three treatment groups (n=12). A single implant was placed in the mandibular midline of participants to support an overdenture using a 6-week loading protocol. The control group received Southern regular implants and standard ball attachments. One group received Southern 8-mm-wide implants and large ball attachments. Another group received Neoss regular implants and Locator attachments. Parametric and non-parametric tests of a statistical software package (SPSS) were used to determine between groups differences in marginal bone loss, implant stability, implant, and prosthodontic success (P<0.05). RESULTS: Implant success after 1 year was 75% for Southern regular implant (control) group; and 100% for the Southern wide and Neoss regular implant groups (P=0.038). Mean marginal bone loss at 1 year was 0.19 mm (SD 0.39) without significant differences observed. Implant stability quotient (ISQ) at baseline was significantly lower for the Southern regular (control) group than the other two groups (P=0.001; P=0.009). At 1 year, no significant difference in implant stability was observed (mean ISQ 74.6, SD 6.1). The change in implant stability from baseline to 1 year was significant for the control group (P=0.025). Prosthodontic success was comparable between the groups but the maintenance (41 events overall, mean 1.2) was greater for the Locator and the standard ball attachments. CONCLUSIONS: Mandibular single-implant overdentures are a successful treatment option for older edentulous adults with early loading protocol using implants of different diameters and with different attachment systems.

Immediate placement or immediate restoration/loading of single implants for molar tooth replacement: a systematic review and meta-analysis.

PURPOSE: This systematic review and meta-analysis assessed the survival of immediately placed single implants in fresh molar extraction sites and immediately restored/loaded single molar implants in healed molar sites. MATERIALS AND METHODS: A search of the main electronic databases, including the Cochrane Oral Health Group's Trials Register, was conducted up to November 1, 2008. The meta-analysis was prepared in accordance with the guidelines of the Academy of Osseointegration Workshop on the State of the Science on Implant Dentistry. The data were analyzed with statistical software. RESULTS: For immediately placed molar implants, nine studies describing 1,013 implants were included to support a survival rate of 99.0%. There were no significant differences between immediate and delayed loading/restoration in molar sites (relative risk of 0.30, 95% confidence interval 0.05 to 1.61; P = .16). For immediate restoration/loading of single implants in healed molar sites, seven studies with 188 single implants were identified. In this case, the implant survival rate was 97.9%, with no difference between immediate and delayed loading (relative risk of 3.0, 95% confidence interval: 0.33 to 27.16; P = .33). Favorable marginal bone level changes in the immediate loading group were detected at 12 months (mean difference of -0.31, 95% confidence interval: -0.53 to -0.096; P = .005). CONCLUSIONS: The protocols of immediate placement and immediate restoration/loading of single implants in mandibular molar regions showed encouraging results.

Primary stability measurements of single implants in the midline of the edentulous mandible for overdentures.

OBJECTIVES: To determine the primary stability of the Southern wide diameter (8 mm) implants, Neoss regular diameter (4 mm) implants, and Southern regular diameter (3.75 mm) implants placed in the midline of edentulous mandibles for single-implant overdentures. Variables related to host site and implant characteristics were investigated to determine their influence on the primary stability of the implants. MATERIALS AND METHODS: A total of 36 implants were placed in the midline symphysis of the edentulous mandibles of 36 participants. Their primary stability was then measured using the magnetic Osstell mentor device. Analysis of variance (ANOVA) was used to compare the mean implant stability quotient (ISQ) scores with one-way ANOVA for multiple comparisons. RESULTS: The highest measurement (ISQ) of primary stability was for the Southern 8 mm wide diameter implants (84.8, SD 9.8), followed by the Neoss 4 mm regular diameter (82.3, SD 4.8) implants and the Southern 3.75 mm regular diameter implants (75.3, SD 8.4), respectively. The Southern 3.75 mm regular diameter implants had a significantly lower mean ISQ value than the same system 8 mm wide diameter (P=0.004) and the Neoss 4 mm regular diameter implants (P=0.03). No significant differences were observed between the 8 mm and the 4 mm diameter implants (P>0.05). CONCLUSIONS: Host-site variables such as age, gender, bone volume, and quality do not appear to influence the primary stability of the implants. No clear correlation was established between ISQ values and implant diameter.

Mandibular single-implant overdentures: a review with surgical and prosthodontic perspectives of a novel approach.

OBJECTIVES: To review the literature on mandibular single-implant overdentures (opposing complete maxillary dentures), and present surgical and prosthodontic perspectives of a novel approach for this treatment option. MATERIAL AND METHODS: An electronic search through the databases of Pubmed, Embase and Medline using the linked key words 'mandibular single implant overdentures' was performed. The search was limited to English language articles published up to August 2008. Hand searches through articles retrieved from the electronic search, peer-reviewed journals and recent conference proceedings were also conducted. RESULTS: A limited number of reports were identified on mandibular single-implant overdentures (opposing maxillary complete dentures). They comprised of case-series reports, short-term prospective trials and current randomized-controlled clinical trials. Different loading protocols with different implant systems have been used, but always with regular diameter implants. Specific anatomical and vascular dangers of the mandibular midline symphysis are identified including a novel surgical approach using a currently available short, wide diameter tapered implant. In addition, the prosthodontic rationale for using a larger attachment system (incorporating a platform switch) for mandibular single-implant overdentures is described. CONCLUSION: The review reveals that there is a lack of published randomized clinical trials using mandibular single-implant overdentures, opposing maxillary complete dentures. Without the evidence from randomized clinical trials, routine use of this novel approach cannot be recommended, compared with using regular diameter implants and matching attachment systems.