Biological aspects of implant dentistry: osseointegration

Nano-superhydrophilic and bioactive surface in poor bone environment. Part 1: transition from primary to secondary stability. A controlled clinical trial : Bioactive implant surfaces in poor density bone

OBJECTIVES

Bioactive surfaces were designed to increase the interaction between the surface and the cells. This may speed up the biological stability and loading protocols.

MATERIALS AND METHODS

36 patients with D3-D4 bone density were recruited and allocated into two groups. 30 bioactive (test group) and 30 traditional (control group) surfaced implants were placed. Insertion torque value (Ncm), insertion torque curve integral (cumulative torque, Ncm), torque density (Ncm/sec), implant stability quotient (ISQ) measured at three timepoints (baseline (T0), 30 (T30) and 45 (T45) days after surgery), and marginal bone loss (MBL) at 6 months of loading were assessed.

RESULTS

The mean ISQ and standard deviation at T0, T30, T45 were respectively 74.57 ± 7.85, 74.78 ± 7.31, 74.97 ± 6.34 in test group, and 77.12 ± 5.83, 73.33 ± 6.13, 73.44 ± 7.89 in control group, respectively. Data analysis showed significant differences between groups in ΔISQ at T0-T30 (p = 0.005) and T30-T45 (p = 0.012). Control group showed a significant decrease in ISQ at T30 (p = 0.01) and T45 (p = 0.03) compared to baseline, while no significant change was observed in test group. Due to the stability of the ISQ value ≥ 70, 26 test group and 23 control group implants were functionally loaded after 45 days. Conversely, due to the ISQ < 70 at T45, four test group implants and one control group implant were loaded after 90 days, and 6 control group implants were loaded after 180 days. Neither insertion torque nor ISQ at baseline were correlated with bone density (in Hounsfield units). There was no significant correlation between cumulative torque and ISQ at baseline. There was a significant positive slope in the correlation between torque density and ISQ at baseline, more accentuated in D3 than D4. This correlation remained significant for the test group in D3 bone at day 30 and 45 (p < 0.01 in both time frames), but not in D4 bone, and it was not significant in CG.

CONCLUSIONS

The bioactive surface showed better behavior in terms of implant stability in D3-D4 bone quality in the early stages of bone healing. Clinical relevance This study demonstrated that the transition from primary to secondary stability is improved using bioactive surface, especially in cases of poor bone environment (D3/D4 bone).

Evaluation of Primary and Secondary Stability of Endosseous Dental Implants With and Without the Use of Platelet-Rich Fibrin: A Clinical Study

BACKGROUND

This clinical study investigates platelet-rich fibrin's (PRF) impact on dental implant stability, addressing global oral health challenges and limitations of traditional methods. Emphasizing osseointegration's pivotal role, the study explores PRF's potential in enhancing implant stability, assessing it through resonance frequency analysis (RFA) and implant stability quotient (ISQ). The hypothesis suggests PRF may improve both primary and secondary stability, aiming to uncover clinical benefits in dental implant procedures Materials and methods: The study involved 24 subjects from the Department of Periodontics outpatient clinics with a meticulously designed methodology. This included a pre-surgical protocol with oral prophylaxis, impressions, and cone-beam computed tomography (CBCT) analysis. PRF preparation utilized a minimally invasive venipuncture technique. Implant placement followed a two-stage surgical protocol, assessing primary stability with MEGA ISQ (Ostell). Post-surgery, patients received instructions and underwent recall for secondary stability after three months. Clinical parameters such as plaque index (PI), gingival index (GI), implant probing pocket depth (IPPD), sulcus bleeding index (SBI), and implant stability (IS) were systematically recorded. Robust statistical analyses, using IBM SPSS Statistics for Windows v20.0 (IBM Corp., Armonk, USA) software, incorporated Mann-Whitney U and Wilcoxon signed-rank tests for group and within-time point comparisons, with a significance level of p<0.05. This comprehensive study yields nuanced insights into the impact of PRF and implant procedures on key clinical parameters, contributing significantly to the field.

RESULTS

This study compared dental implants with and without PRF in 24 patients. Both groups showed significant improvements in the PI, GI, and SBI. The PRF group exhibited higher IS in the third and sixth months, while IPPD was lower in the PRF group in the sixth month.

CONCLUSION

The findings of the study highlight a positive impact on implant stability contributing to better implant outcomes.

Comparison of crestal bone loss and papilla fill after conventional and immediate implant placement: A 12 month clinical and radiographic prospective study

Background

The problem of missing teeth persists in all age groups. The main objective of implants in dentistry is to provide a restoration that reconstructs the shape and restores esthetics and functions of edentulous areas. The objectives of this study are to compare the crestal bone level changes and papillary fill after placement of implants in fresh extraction socket, i.e. immediate implant placement, and healed extraction socket, i.e. delayed or conventional implant placement, and to assess other clinical parameters such as modified plaque index (mPI), modified gingival index (mGI) and gingival biotype in between the groups and within the groups.

Methods

18 patients were recruited in the study out of which 9 patients received implants as per immediate implant placement protocol (group 1) and 9 patients received implants as per conventional implant placement protocol (group 2). All patients were evaluated for gingival biotype, mPI and mGI and papillary fill was assessed as per Jemt's papilla score as clinical parameters. Implant site was assessed for radiographic bone loss using Image J software. Statistical analysis was performed using independent t test, paired t test and chi square test.

Results

At the end of 1 year, results showed that crestal bone loss was seen more in the immediate group than the conventional group. Conventional implants showed better papillary fill than implants placed in fresh extraction sockets. Plaque scores were assessed as per modified plaque index, which showed better results in the conventional group. Modified gingival index was used to assess gingival status which showed better results in the immediate group one year later.

Conclusions

Findings from the study suggest that crestal bone loss was found to be increased in the immediate group than the conventional group and papillary fill was better in the conventional group than the immediate group.Registration: CTRI ( CTRI/2019/09/021340).

A Comparative Evaluation of Soft and Hard Tissue Changes Around Dental Implants Placed With and Without Platelet-Rich Fibrin

BACKGROUND

A patient's ability to maintain a healthy bone-implant interface seems to be a major predictor of implant longevity over the long term. The implant surface is protected from the oral environment, the bone, and the implant itself by the peri-implant tissues. Platelet-rich fibrin (PRF) has been shown to help in the regeneration of bone and other connective tissues. Since there has been inadequate information on the role of PRF in maintaining soft tissue integrity and crestal bone changes, the present study aimed to evaluate these challenges clinically and radiographically in human patients who had dental implants placed with PRF.

MATERIALS AND METHODS

There were a total of 15 patients who were recalled for the analysis, and they were split into two groups. PRF was used to complete the implant procedure in the experimental group, but PRF was not used in the control group. Cone beam computed tomography (CBCT) was used to evaluate the amount of alveolar bone prior to dental implant placement and intra-oral periapical radiograph (IOPAR) for postoperative assessment. Gingival index, plaque index, probing depths, papilla bleeding index, and crestal bone changes were used to document clinical limits. IOPAR using a similar approach was used to evaluate the crestal bone level alterations. Patients were evaluated clinically and radiographically for changes in the peri-implant soft tissue and crestal bone during implant placement, six and nine months postoperatively.

RESULTS

From baseline (p=0.02) to six months (p=0.04) and nine months (p=0.04), both groups showed changes in crestal bone loss and soft tissue although the changes in the test group were smaller. Soft tissue changes showed significant differences for probing depth and papilla index score at baseline and at the end of the six and nine months (p<0.05), whereas no significant difference was noted with bleeding index and plaque index score during the follow-up (p>0.05).

CONCLUSION

 To conclude, the provided data demonstrated that the local injection of PRF during implant placement has the potential to favorably stimulate bone formation, and may be used as a therapeutic adjuvant in the clinical setting of implant placement.

Screw-Type Collar vs. Non-Screw-Type Collar Implants—Comparison of Initial Stability, Soft Tissue Adaptation, and Early Marginal Bone Loss—A Preclinical Study in the Dog

Simple Summary

Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. Screw-type rough-surface collar implants had statistically significant poorer soft tissue healing and increased marginal bone loss compared to non-screw type implants at the time of 2nd-stage surgery. The significance of the novel implant design results in preventing EMBL awaits further research.

Abstract

Background: Implant neck characteristics may affect initial implant stability, soft tissue healing, and early marginal bone loss (EMBL) at second-stage surgery. The null hypothesis was that, following two-stage implant insertion, rough surface, non-screw-type collar implants will present lower EMBL at 2nd-stage surgery than rough-surface, screw-type collar implants. Methods: The study comprised seven male beagle dogs (mean weight 10.57 ± 2.8 kg; range 9–17 kg). A novel implant design was developed, composed of 2 parts: an apical part resembling a regular threaded implant, and a coronal non-screw-type collar, 4.2 mm long, served as the study group, whereas standard threaded implants served as control. Twenty-eight implants were placed: two on each side of the mandible. All implants were sand-blasted/acid-etched and of similar dimensions. Each dog received four implants. To assess location (anterior vs. posterior) impact on the outcomes, implants were placed as follows: group I—posterior mandible right—non-screw-type collar implants; group II—anterior mandible right—similar non-screw-type collar implants. To assess the collar-design effect on the outcomes, implants were placed as follows—Group III—anterior mandible left—control group, screw-type collar implants; Group IV—study group, posterior mandible left—non-screw-type collar implants. The following parameters were measured and recorded: insertion torque, soft tissue healing, early implant failure, and EMBL at 2nd-stage surgery. Results: No statistically significant differences were noted between groups I and II regarding all outcome parameters. At the same time, although insertion torque (55 N/cm) and early implant failure (0) were similar between groups III and IV, group III presented significantly poorer soft tissue healing (1.43 vs. 0.14) and increased marginal bone loss (0.86 vs. 0 mm). Conclusions: When a two-stage implant protocol was used, rough-surface non-screw-type collar implants led to superior outcomes at 2nd-stage surgery. Implant location did not affect the results. The significance of this result in preventing EMBL awaits further research.

Damaged Mesenchymal Cells Dampen the Inflammatory Response of Macrophages and the Formation of Osteoclasts

Damage to mesenchymal cells occurs by dental implant drills as a consequence of shear forces and heat generation. However, how the damaged mesenchymal cells can affect the polarization of macrophages and their differentiation into osteoclastogenesis is not fully understood. To simulate cell damage, we exposed suspended ST2 murine bone marrow stromal cells to freeze/thawing or sonication cycles, followed by centrifugation. We then evaluated the lysates for their capacity to modulate lipopolysaccharide-induced macrophage polarization and RANKL-MCSF-TGF-β-induced osteoclastogenesis. We report that lysates of ST2, particularly when sonicated, greatly diminished the expression of inflammatory IL6 and COX2 as well as moderately increased arginase 1 in primary macrophages. That was confirmed by lysates obtained from the osteocytic cell line IDG-SW3. Moreover, the ST2 lysate lowered the phosphorylation of p65 and p38 as well as the nuclear translocation of p65. We further show herein that lysates of damaged ST2 reduced the formation of osteoclast-like cells characterized by their multinuclearity and the expression of tartrate-resistant phosphatase and cathepsin K. Taken together, our data suggest that thermal and mechanical damage of mesenchymal cells causes the release of as-yet-to-be-defined molecules that dampen an inflammatory response and the formation of osteoclasts in vitro.

Intra- and inter-operator concordance of the resonance frequency analysis. A cross-sectional and prospective clinical study

OBJECTIVE

Resonance frequency analysis (RFA) provides an evaluation of implant stability over time. This analysis is a non-invasive, precise, and objective method. Several studies compare the RFA system with other devices. However, few investigations analyze repeatability and reproducibility between different operators. The aim of this study was to evaluate the intra- and inter-operator concordance of the Osstell® ISQ.

MATERIAL AND METHODS

RFA measurements were performed with Osstell® ISQ in a total of 37 implants placed in 21 patients. At the time of implant placement, 6 measurements per implant were taken by three different experienced operators. Three measurements were carried out consecutively and three by removing and placing the SmartPeg-Osstell® to assess intra-operator and inter-operator agreement.

RESULTS

Intra-operator concordance according to the intraclass correlation coefficient (ICC) showed high concordance. The ICC values were higher than 0.9 (p < 0.0001) for consecutive measures and alternative measures, being almost perfect of Landis & Koch classification. For inter-operator concordance The ICC was 0.709 (p < 0.0001) and 0.670 (p < 0.0001) for consecutive and alternative measures, respectively, both estimates being in the substantial category. In torque and ISQ values, no statistically significant differences were observed when operators and measurements were compared.

CONCLUSIONS

Osstell® ISQ system was stable both in intra-operator and inter-operator measurements. This device has excellent repeatability and reproducibility, demonstrating reliability to measure the stability of dental implants.

CLINICAL RELEVANCE

Resonance frequency analysis (RFA) is a non-invasive, objective, and reliable diagnostic method to determine the ideal moment to load the implant, as well as to predict possible failures.

Efficacy of titanium brush, 915 nm diode laser, citric acid for eradication of Staphylococcus aureus from implant surfaces

BACKGROUND

This study aimed to assess the efficacy of titanium brush, 915 nm diode laser, citric acid and the combination of latter two with titanium brush for decontamination of SLA surface mini-implants.

METHODS

Seventy-five mini-implants contaminated with Staphylococcus aureus (S. aureus) were randomly divided into five experimental groups (n = 12) of titanium brush (TiB), laser, citric acid (CA), brush-laser, and brush-acid, positive [n = 12; chlorhexidine mouthwash (CHX)] and negative [n = 2; phosphate buffered saline (PBS)] control groups and one no-treatment group (n = 1). After counting the colony forming units (CFUs), data were analyzed using the Kruskal-Wallis and Dunn post-hoc tests.

RESULTS

Regardless of the no-treatment and negative control groups, maximum and minimum CFUs were noted in the titanium brush and positive control groups. After CHX, minimum CFUs were noted in brush-acid group followed by brush-laser, laser, and acid groups. Generally, the Kruskal-Wallis test revealed a significant difference between the groups regarding the colony count (P < 0.001). Dunn post-hoc test showed that the difference between the titanium brush and acid-brush group was significant (P < 0.001) while the differences between the brush and laser groups with the brush-laser group were not significant (P > 0.077).

CONCLUSIONS

Combined use of titanium brush and citric acid yielded superior results compared to other groups in reduction of S. aureus on implant surface.

Surface Characterization and Assessment of Biofilm Formation on Two Titanium-Based Implant Coating Materials

Implant-related oral diseases such as peri-implantitis and peri-mucositis are largely initiated by bacterial colonization on artificial implant surfaces. Therefore, implant and abutment material characteristics that minimize bacterial attachment and subsequent biofilm formation are important factors in reducing the risk of infection-related implant failure. This study compares the properties of two different titanium-based implant coating materials, titanium nitride (TiN) and titanium carbon nitride (TiCN). Surface hydrophilicity/ hydrophobicity and roughness were evaluated via contact angle measurements and surface profiling with white light interferometry, respectively. TiN-coated surfaces were hydrophobic according to its contact angle higher than 72.7°, whereas TiCN-coated surfaces were hydrophilic with its contact angle of 53.6°. The average roughness (Ra) was greater for TiCN than TiN with the root mean square roughness (Rq) being significantly higher. These findings are in contrast to the common understanding for titanium-based materials that surface roughness and hydrophobicity are positively correlated. A well-established saliva-based oral microbial biofilm model was employed to compare bacterial attachment and biofilm formation on TiN and TiCN. Growth conditions included relevant host components such as blood as well as the presence or absence of dietary carbohydrates. The accumulated biomass was measured by crystal violet staining and the bacterial community profiles of the attached biofilms were determined via 16S rRNA gene microbiome sequencing at different time points over a 7-day period. At all time points, TiCN showed significantly less bacterial attachment and biofilm formation compared to TiN. This implied the importance of the hydrophilic state over surface roughness as parameter for the prevention of oral microbial attachment. Although, the biofilm community composition was very similar on both materials, environmental growth conditions resulted in significantly different bacterial profiles independent of the surface. In conclusion, TiCN coating produced a unique titanium surface which is rougher but more hydrophilic. TiCN-coated surfaces exhibited reduced bacterial attachment and biofilm formation in comparison to TiN coating. This coating technique can be further explored to improve implant and abutment success.

Evaluation of hard and soft tissue changes around implant in partially edentulous patients: a clinico-radiographic study

Introduction

implant supported prosthesis has become a viable treatment option for missing teeth. An important tool to detect early changes around implants is the standardized assessment of peri-implant hard and soft tissue parameters. The purpose of this prospective study was to clinically and radiographically assess the soft and hard tissues around implants.

Methods

ten (10) patients with 13 implant supported prosthesis were included in the study. Clinical parameters plaque index (PI), gingival index (GI), modified sulcus bleeding index (mSBI), peri-implant Probing Depth (PD), gingival margin Level, width of keratinized mucosa (WKM) and implant mobility were measured at loading and at 3 and 6 months. The radiographic crestal bone loss and peri-apical implant radiolucencies were also evaluated at loading and at 3 and 6 months. Student paired t test and correlation and regression analysis was done to evaluate the effect of clinical variables over bone loss.

Results

there was decrease in the site specific PI, GI, mSBI and peri-implant PD and an increase in the gingival recession from baseline to 6 months. The WKM remained stable throughout the study. Significant crestal bone loss was observed around implants more on the distal as compared to the mesial aspect. No mobility or peri-apical implant radiolucency was observed. Regression analysis of the confounding variables with bone loss showed no significant effect.

Conclusion

the occlusal loading of implants after 6 months showed significant bone loss (<1mm), which was within acceptable limits and the soft tissues around implants were in good health.

Mechanical Pull-Out Test of a New Hybrid Fixture-Abutment Connection: An In Vitro Study

Implant abutment connection was described among the main causes of peri-implant bone resorption. The aim of this in vitro study was to test the coupling capacity, the surface modification of a new hybrid connection and the influence of repeated connection activations caused during the main clinical and laboratory phases. A total of 40 implant-abutment screw retained systems with 10°-conical and internal hexagon connection were tested. The connection was screwed, fixed to the universal test machine, removed the screw and a pull-out test was performed. Test was repeated five times in succession. Also Scanning Electron Microscopy (SEM) was used to detect microscopically surface modification. Analysis of variance and Tukey tests were used for the statistical analysis. Pull-out test reveals a mean value of 131.35 ± 16.52 Newton Centimeter (N·cm). For each single activation, results from first to fifth were: 113.9 ± 13.02, 126.1 ± 12.81, 138.11 ± 15.15, 138.8 ± 11.90 and 140 ± 12.99 N·cm. A statistically significant difference between the measurements and an increase in the removal force was shown. The collected data supports the use of this new type of connection, resulting in a very strong interface between implant and abutment. Also, repeated activation of connection can promote a better coupling of the implant-abutment interface.

Evaluation of papilla levels following three different techniques for the second stage of implants - A clinical and radiographic study

Objective:

Papilla formation after placement of an implant is influenced by the underlying bone and the periodontal biotype. The second-stage surgery to uncover the implants may have an effect on the regeneration of papilla and various techniques such as the scalpel, diode laser, and punch technique are used. In the present study, an attempt has been made to evaluate papillary fill levels following three different techniques of second-stage implant surgery.

Materials and Methods:

A total of 35 patients with 45 implants (39 single implants and 3 sites with two adjacent implants) were randomly divided into three groups with 15 implants each: second-stage implant surgery with midcrestal incision using scalpel (Group I), with I-shaped incision using scalpel (Group II), and using diode laser (Group III). The mean papillary fill and mean crestal bone loss for all three groups were compared at baseline, 3 months, and 6 months of prosthesis delivery.

Results:

Complete papilla fill at 6 months was seen in 60% and 73.3% of sites in Group II and Group III, respectively. Bone level contacting implant and adjacent teeth was less in both Groups II and III. Bone level from the contact point to the bone crest was least in Groups II and III.

Conclusion:

The use of diode laser during second-stage surgery showed maximum papillary fill and minimal crestal bone loss when compared with other two techniques. Irrespective of technique used for second-stage surgery, bone loss did occur after prosthesis delivery.

Hip hemiarthroplasty for femoral neck fractures in end-stage renal disease patients on dialysis compared to patients with late-stage chronic kidney disease

INTRODUCTION

Hip fractures in patients with end-stage renal disease (ESRD) are associated with frequent complications and poorer outcomes. Patients on chronic dialysis are at additional risk of dialysis-related complications such as myocardial infarction and early osteolysis. We analysed the complications and implant survivorship of hemiarthroplasty in patients with femoral neck fractures with late-stage chronic kidney disease with and without pre-existing dialysis.

METHODS

We conducted a retrospective case-control study of 28 patients with ESRD and 31 patients with chronic kidney disease (CKD) Stages 3-5, who had a total of 62 fractures treated with hemiarthroplasty between 2005 and 2015. The mean age of the patients was 68.33 (50.21-86.45) years. The mean follow-up time of the group was 39 months. Patient demographics, complications, outcomes and follow-up radiographs were analysed for differences.

RESULTS

Patient in both groups had statistically similar demographics and comorbidity scores except for a higher incidence of hyperparathyroidism in ESRD patients on chronic dialysis (nine patients vs. zero patients; p = 0.001). These patients were more likely to develop cardiopulmonary complications in the perioperative period (odds ratio [OR] 5.04; p = 0.04) and implant loosening on radiographic analysis (OR 8.75; p = 0.02). The incidence of loosening was higher in patients with hyperparathyroidism (OR 9.80; p = 0.002). Cemented techniques, however, did not appear to be significantly associated with intraoperative fractures or loosening.

CONCLUSION

Patients with ESRD on chronic dialysis were more likely to develop cardiopulmonary complications and implant loosening after hemiarthroplasty for femoral neck fractures. Hyperparathyroidism should be optimised, as it may prevent loosening. Our study did not show any difference in complications or outcomes for cemented fixation.

Single-cell adhesion of human osteoblasts on plasma-conditioned titanium implant surfaces in vitro

OBJECTIVES

This study aimed to demonstrate the effect of treating titanium-implant surfaces with plasma from two different sources on wettability and initial single-cell adhesion of human osteoblasts and to investigate whether aging affects treatment outcomes.

METHODS

Titanium disks with sandblasted and acid-etched (SLA) surfaces were treated with atmospheric pressure plasma (APP) and low-pressure plasma (LPP). For wetting behavior of the specimens after plasma treatment, the water contact angle was measured. The single-cell detachment force and amount of work of detachment of human osteoblasts were determined with single-cell force spectroscopy (SCFS). To evaluate the aging effect in APP-treated specimens, SCFS was conducted 10 and 60 min after treatment.

RESULTS

Significantly higher hydrophilicity was observed in the APP and LPP treatment groups than in the control group, but no significant difference was observed between the APP and LPP groups. No significant difference in cell-detachment force or work of detachment was observed, and there were no significant differences according to the conditioning mechanisms and storage time.

SIGNIFICANCE

Conditioning of the titanium surfaces with APP or LPP was not a significant influencing factor in the initial adhesion of the osteoblasts.

Comparison of histomorphometry and microradiography of different implant designs to assess primary implant stability

OBJECTIVES

To contribute toward optimizing the long-term stability of dental implants. Our working hypothesis was that the degrees of immediate implant-bone contact, and hence of primary stability, would demonstrably differ between implant systems due to their different external geometries and thread designs (macro-design). This demonstration was provided in a bovine model (ex vivo) by employing and comparing histomorphometry and microradiography as evaluation methods.

MATERIALS AND METHODS

A total of 120 implants, representing six different implant thread designs, were inserted following the recommended surgical protocol in ribs of freshly slaughtered cattle. Twenty specimens of implants with surrounding bone were prepared per system and were divided into two equally sized groups of 60 specimens for analysis by either histomorphometry or micro-computed tomography. Data were analyzed by Mann-Whitney U test (P ≤ .05).

RESULTS

One of the implant systems, featuring a slight tapered external geometry and a progressive thread design, consistently revealed the most favorable bone-implant contacts in both histomorphometric and microradiographic evaluations. Overall, consistently higher values of bone-implant contact were obtained with the microradiographic than the histomorphometric approach, and this difference reached statistical significance in three of the six implant systems tested.

CONCLUSIONS

Progressive threads offering a bone-condensing effect can significantly help to maximize implant-bone contact percentages. Compared to histomorphometry, microradiography is likewise a suitable method to evaluate bone-implant contact, offering the additional benefits of being noninvasive and less time consuming.

In vitro study of surface alterations to polyetheretherketone and titanium and their effect upon human gingival fibroblasts

STATEMENT OF PROBLEM

Soft-tissue attachment to different surfaces may play a pivotal role in the long-term success of dental implants. However, studies on the issue, especially on newer materials, are sparse.

PURPOSE

The purpose of this in vitro study was to evaluate the viability and adhesion of human gingival fibroblasts (HGFs) on different implant abutment materials with specific surface modifications.

MATERIAL AND METHODS

One hundred and fifty specimens in 6 experimental groups were evaluated: smooth-machined titanium alloy (Ti), laser-modified titanium (TiL), smooth-machined polyetheretherketone (PEEK) (P), laser-modified PEEK (PL), plasma-treated PEEK (PP), laser- and plasma-treated PEEK (PLP). Machined Ti was considered as the control group. Surface roughness (S_a), water contact angle (WCA), and X-ray photoelectron spectroscopy (XPS) were measured. HGF attachment and proliferation were observed at 1, 3, and 7 days after cell seeding. Comparison of the means among the groups was performed with 1-way analysis of variance (ANOVA) with post hoc comparison using the Tukey test (α=.05).

RESULTS

S_a values of the laser modified groups were significantly higher than those of the nonmodified (smooth-machined) groups (P<.001). WCAs were significantly different among PEEK groups, and plasma-sprayed groups had the lowest WCAs. XPS analysis of both Ti and PEEK groups showed laser treatment did not have any significant effect on the surface composition of the PEEK as the same bonds with similar ratio/fraction were detected in the spectrum of the modified specimens. Scanning electron microscopy (SEM) revealed more functionally oriented HGF cells on the laser-grooved surfaces. On the first, third, and seventh day of proliferation, the titanium groups showed no significant differences (P>.05). On the first and third days of proliferation, the plasma sprayed groups (PP, PLP) showed significantly greater proliferation than all experimental groups (P<.001). On the seventh day of proliferation, statistically significant differences were observed between all PEEK groups and between all PEEK groups and the Ti group (P<.001), with the exception of the PL and P groups and the PLP and Ti groups (P>.05).

CONCLUSIONS

Laser-modified titanium and PEEK surfaces led to guided gingival fibroblast attachment. Plasma treatment of PEEK surfaces increased the wettability of this polymer and improved proliferation of HGF.

Patient compliance as a risk factor for the outcome of implant treatment

Peri-implantitis can be explained using a multicausality model. Many factors are involved in the etiology of peri-implantitis, but patient compliance also plays a key role. Oral hygiene, attending recall visits, smoking behavior, and therapy comprehension are relevant factors that contribute to peri-implant health. The clinician should create the most optimal conditions for patients to facilitate adequate oral self-care and to help patients improve their oral hygiene skills. Implementation of a supportive periodontal therapy program is mandatory to control inflammation and plaque accumulation, as well as to keep the incidence of peri-implant diseases low. Patient compliance, including plaque control and dental follow-up, must be optimal. Consequently, precautions must be taken with patients treated with dental implants.

Titanium dental implants with different collar design and surface modifications: A systematic review on survival rates and marginal bone levels

AIM

The aim of this study was to compare clinical and radiographic outcomes of dental implants with different neck characteristics.

METHODS

A protocol-oriented search aimed at the question: "In patients subjected to tooth replacement with screw-type dental implants does the modification of the implant neck macro- or microgeometry contribute to the improvement of survival rates and maintenance of the peri-implant marginal bone levels?" Primary outcomes were survival and marginal bone level (MBL) changes evaluated on randomized controlled trials with >10 participants and follow-up >1 year. Risk of bias was evaluated using the Cochrane Collaboration's tool. The review follows the PRISMA statement.

RESULTS

Forty-three studies compared: (a) One- versus two-piece implants (N = 7); (b) Two-piece implants with different neck characteristics (machined and rough collars, microthreads, LASER microtexturing) (N = 21); (c) Two-piece implants with macrogeometry modifications (tapering, back-tapering, and scalloping) (N = 6). One- and two-piece implants showed similar survival (RR = 0.45, 95% CI: [0.12, 1.66], p = 0.23) and MBL changes (WMD = 0.09 mm, 95% CI: [-0.27, 0.45], p = 0.64) at 1-year post-loading. Machined collar implants have higher risk of early failure than rough collar implants (RR = 3.96, 95% CI: [1.12, 13.93], p = 0.03) and 0.43 mm higher bone resorption (95% CI: [0.0, 0.86], p = 0.05). Microthreads (WMD = 0.07 mm, 95% CI: [-0.01, 0.15], p = 0.10) and LASER microtexturing (WMD = 0.15 mm, 95% CI: [-0.35, 0.65], p = 0.56) do not reduce bone resorption. Scalloped implants have 1.26 mm higher resorption (95% CI: [0.72, 2.00], p < 0.001).

CONCLUSIONS

One- and two-piece implants have similar survival and MBL changes. Rough collar implants have lower MBL changes than machined collar implants. Additional modifications to rough collars are irrelevant.

Peri-Implant Bone Resorption during Healing Abutment Placement: The Effect of a 0.20% Chlorhexidine Gel vs. Placebo-A Randomized Double Blind Controlled Human Study

Introduction

Peri-implant marginal bone loss (MBL) seems to be more pronounced in the first year of loading despite all the studies and changes implemented to reduce it. Among the different causes, the presence of a microgap makes the interface between fixture and abutment colonizable by bacteria, causing an inflammatory response and consequent bone resorption. To reduce this several local antiseptics like chlorhexidine digluconate (CHX) were used after surgical procedures.

Aim

The objective was to radiologically compare the MBL when a 0.20% CHX gel or a placebo gel was applied to the implant-abutment interface during all surgical and prosthetic phases and for a follow-up period up to 12 months.

Method

32 patients (16 for each Group A and B) were enrolled and rehabilitated with a single implant (Cortex classic, Cortex, Shalomi, Israel). During each of the clinical stages a gel containing 0.20% CHX (Plak ®Gel; Polifarma Wellness Srl, Rome, Italy) or a placebo gel (Placebo, Polifarma Wellness Srl, Rome, Italy) was used as indicated by the randomization chart. In order to compare radiographic modification intraoral radiographs was taken. Also, clinical data regarding implant or prosthetic failure and gingival index were recorded. Data were presented as means and standard deviations (SD) and used for the statistical analysis.

Results

All implants showed no bleeding on probing and a very small plaque score at the 1 year of follow-up. MBL was statistically significantly different between the groups in every stage.

Conclusion

Results obtained showed that the use of CHX gel inside the connection significantly reduces MBL during the first year. A rigid disinfection protocol with 0.20% CHX from the time of implant insertion to crown delivery is recommended to reduce host inflammatory response and consequently MBL. This trial is registered with ClinicalTrials.gov Identifier: (Registration Number: NCT03431766).

Impact of Inorganic Xenograft on Bone Healing and Osseointegration: An Experimental Study in Rabbits

PURPOSE

To evaluate if an inorganic graft applied before implant insertion interferes with osseointegration.

MATERIALS AND METHODS

The bilateral mandibular incisors of 12 rabbits were extracted. One of the sockets was randomly filled with an inorganic xenogenic bone graft, whereas the remaining socket was allowed to heal naturally and served as a control. After 60 days, titanium implants were inserted into healing areas. The animals were killed 60 days after. Bone depositions were marked with fluorochrome oxytetracycline, alizarin, and calcein and evaluated using confocal laser scanning microscopy. Bone-to-implant contact (BIC) and bone area (BA) within the limits of the implant threads were analyzed. Data were compared statically by paired t tests, one-way ANOVA, and Bonferroni post hoc tests (α = 0.05).

RESULTS

No differences between the control and experimental groups in bone deposition for each marker, in either the BIC or BA analysis were observed. The bone deposition marked by alizarin (14-21 days) was the highest, followed by oxytetracycline (0 and 7 days) and calcein (45 and 52 days) in both groups (P < 0.05).

CONCLUSION

The bone healing or the course of osseointegration was not impaired by the use of an inorganic xenogenic graft before insertion of a titanium implant.

Chronic Periodontitis and RANKL/OPG Ratio in Peri-Implant Mucosae Inflammation

tHistory of chronic periodontitis (CP) is a risk factor for oseointegration failure. The osteoclastogenesis system (RANK, RANKL and OPG) is critical for bone homeostatic control. We investigated the levels of OPG and RANKL in peri-implant tissues from volunteers with and without a history of CP and their association with mucosae inflammation. This is a single-blind case-contro study. Diagnosis of a history of CP and peri-implant examination was performed on 46 volunteers, divided into control (without history of CP, n=26) and CP group (with history of CP, n=20). Gingival biopsies were harvested during implant exposure. Quantitative PCR evaluated OPG/RANKL mRNA expressions. OPG and RANKL proteins were analyzed by western blot and immunohistochemistry assay. The chi-square test analyzed the significance of nominal variables between groups while continuous variables were analyzed by T-test or Mann-Whitney test, after Shapiro-Wilk test evaluation. The 2-ΔΔCT Livak method calculation evaluated the gene expression. Values of p<0.05 were considered statistically significant. Volunteers with CP history had 23 times higher chance of developing mucosae inflammation. High mucosae levels of RANKL (p=0.04) and RANKL/OPG (p=0.001) mRNA expressions were observed in CP group. CP volunteers showed increased RANKL protein levels in opposition to decreased OPG expression. Even without active periodontitis, volunteers with a history of CP had elevated gingival levels of RANKL/OPG and higher correlation with peri-implant mucosae inflammation and implant loss.

Retracted: A new cervical implant design compared with standard design in order to increase peri-implant hard and soft tissue behavior: histomorphometric and histological study in dogs

OBJECTIVE

The aim of this study was to evaluate a new design of the cervical portion of dental implant with the objective to increase the volume of peri-implant tissues in the crestal area.

MATERIALS AND METHODS

Forty-eight tapered dental titanium implants with internal conical connection were implanted in healed alveolar sites of six dogs. Twenty-four conventional implants design (C1 implant) formed the control group, and 24 new implant design (V3 implant) formed the test group. The groups were randomized. Histological, histomorphometric, and implant stability quotient were performed. After 12 weeks of healing period, histomorphometric analyses of the specimens were carried out to measure the crestal bone level values and the tissue thickness in the cervical implant portion. The data were compared using statistical tests (α = 5%).

RESULTS

The mean of the measurements in the buccal and lingual aspects measured of crestal bone level was 0.31 ± 0.24 mm and 0.30 ± 0.19 mm in the control group, respectively, and 0.71 ± 0.28 and 0.42 ± 0.30 mm in the test group, respectively, whereas the mean of the tissue thickness was 1.63 ± 0.33 mm and 2.04 ± 0.23 mm in the control group, respectively, and 2.11 ± 0.35 mm and 2.51 ± 0.41 mm in the test group.

CONCLUSIONS

Within the limitations of this study, our findings suggest that more thickness of peri-implant hard and soft tissues may be expected in this new implant design. However, the control group with traditional implant design was found to have more height values of the crestal bone compared with new V3 implants.

An oral multispecies biofilm model for high content screening applications

Peri-implantitis caused by multispecies biofilms is a major complication in dental implant treatment. The bacterial infection surrounding dental implants can lead to bone loss and, in turn, to implant failure. A promising strategy to prevent these common complications is the development of implant surfaces that inhibit biofilm development. A reproducible and easy-to-use biofilm model as a test system for large scale screening of new implant surfaces with putative antibacterial potency is therefore of major importance. In the present study, we developed a highly reproducible in vitro four-species biofilm model consisting of the highly relevant oral bacterial species Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis. The application of live/dead staining, quantitative real time PCR (qRT-PCR), scanning electron microscopy (SEM) and urea-NaCl fluorescence in situ hybridization (urea-NaCl-FISH) revealed that the four-species biofilm community is robust in terms of biovolume, live/dead distribution and individual species distribution over time. The biofilm community is dominated by S. oralis, followed by V. dispar, A. naeslundii and P. gingivalis. The percentage distribution in this model closely reflects the situation in early native plaques and is therefore well suited as an in vitro model test system. Furthermore, despite its nearly native composition, the multispecies model does not depend on nutrient additives, such as native human saliva or serum, and is an inexpensive, easy to handle and highly reproducible alternative to the available model systems. The 96-well plate format enables high content screening for optimized implant surfaces impeding biofilm formation or the testing of multiple antimicrobial treatment strategies to fight multispecies biofilm infections, both exemplary proven in the manuscript.

Retrospective clinical study of an implant with a sandblasted, large-grit, acid-etched surface and internal connection: analysis of short-term success rate and marginal bone loss

Background

The purpose of this retrospective study was to evaluate the clinical utility of an implant with a sandblasted, large-grit, acid-etched (SLA) surface and internal connection.

Methods

Six patients who received dental implants in the Department of Oral and Maxillofacial Surgery, Chonnam National University Dental Hospital, were analyzed by factors influencing the success rate and marginal bone loss. Factors included patient’s age, sex, implant installation site, whether bone graft was done, type of bone graft materials, approaching method if sinus lift was done, and the size of the fixture. In addition, the marginal bone loss was analyzed by using a radiograph.

Results

All implants were successful, and the cumulative survival rate was 100 %. Average marginal bone loss of 6 months after the installation was 0.52 mm and 20 months after the functional loading was 1.06 mm. Total marginal bone resorption was 1.58 mm on average. There was no statistically significant difference in mesial and distal marginal bone loss.

Conclusions

The short-term clinical success rate of the implant with an SLA surface and internal connection was satisfactory. Moreover, the marginal bone loss was also consistent with the implant success criteria.

Bone level changes around platform switching and platform matching implants: a systematic review with meta-analysis

The amount of marginal bone loss is considered an important criterion to evaluate the implant therapy outcome and to predict the prognosis of the implant rehabilitation. The purpose of this systematic review was to examine the available literature comparing clinical and radiological outcomes like the implant failure rates and marginal bone loss around platform switching dental implants versus platform matching ones. English randomized controlled human clinical trials, comparing one or more PS groups with one or more PM groups, with at least 12 months of follow-up after loading and 10 implants, providing carefully the number of PS- and PM- implants used as well as implant survival and data concerning bone level changes or marginal bone loss around implants, were included. Fifteen publications, involving a total of 1439 implants and 642 patients, were eligible. More studies showed less mean marginal bone loss around PS implants and none of them showed differences in terms of implant failure rates. This review confirmed a great effectiveness of platform switching technique to prevent marginal bone resorption. Nevertheless, this result should be interpreted cautiously because of the heterogeneity of the included studies.

Esthetic Assessment of Implants Placed into Fresh Extraction Sockets for Single-Tooth Replacements Using a Flapless Approach

BACKGROUND

To validate the concept of immediate implant placement and nonfunctional loading for use in the esthetically sensitive anterior maxilla, clinical trials should ideally include objective esthetic criteria.

PURPOSE

This study analyzed procedural results as graded by the pink esthetic score and white esthetic score (PES/WES).

METHODS

Thirty-nine suitable patients (mean follow-up 44.82 ± 28 months) were evaluated.

RESULTS

Thirty-eight implants fulfilled stringent criteria for successful osseointegration: absence of peri-implant radiolucency, implant mobility, suppuration, and pain. The mean total PES/WES was 15.50 ± 2.67 (range: 10-20). The mean total PES of 7.92 ± 1.60 (range: 5-10) indicated favorable overall peri-implant soft-tissue conditions. Root convexity and texture (1.63 ± 0.54) and curvature of the facial mucosa (1.68 ± 0.47) and distal papilla (1.66 ± 0.48) had the highest mean values, whereas acceptable levels of facial tissue (1.53 ± 0.73) and mesial papilla (1.42 ± 0.64) were the most difficult to fully achieve. The mean mesial and distal bone loss at data collection was, was 1.19 ± 0.54 and 1.15 ± 0.51, respectively. Periodontal disease severity (advanced chronic and aggressive periodontitis) was significantly associated with a low total PES (p = .048).

CONCLUSIONS

Objective PES/WES assessment validated immediate anterior maxillary single-tooth replacement and restoration as being a successful and esthetically predictable treatment modality in sites where the buccal bone had been preserved during the extraction at 1 year of follow-up.

Effect of platform switching on crestal bone levels around implants in the posterior mandible: 3 years results from a multicentre randomized clinical trial

Objective

Evaluation of differences in the clinical performance and crestal bone levels between implants restored with single crowns with platform‐matched or platform‐switched abutments after 3 years.

Material and Methods

The study enrolled adult patients missing two or more adjacent teeth in the posterior mandible with natural teeth mesial to the implant site. Randomization followed open‐flap implant insertion and the corresponding matching or switching healing abutments placed at surgery. Conventional loading was made with cemented crowns. Clinical follow‐up took place annually after loading up to 3 years. Bone level changes were measured in standardized radiographs as the variation in crestal bone from one evaluation to the next.

Results

Sixty‐three patients with a total of 135 implants (66 platform matching, 69 platform switching) were analysed. From surgery to 36 months, mean bone loss was 0.28 ± 0.56 mm for the platform‐switching group and 0.68 ± 0.64 mm for the platform‐matching group. A statistically significant difference was found between groups (p = 0.002) with an estimate of 0.39 mm (0.15–0.64, 95% CI) in favour of platform switching.

Conclusions

After 3 years, platform‐switching restorations showed a significant effect in the preservation of marginal bone levels compared to platform‐matching restorations.

A systematic review on the long-term success of calcium phosphate plasma-spray-coated dental implants

The objectives of the current review were (1) to systematically appraise, and (2) to evaluate long-term success data of calcium phosphate (CaP) plasma-spray-coated dental implants in clinical trials with at least 5 years of follow-up. To describe the long-term efficacy of functional implants, the outcome variables were (a) percentage annual complication rate (ACR) and (b) cumulative success rate (CSR), as presented in the selected articles. The electronic search yielded 645 titles. On the basis of the inclusion criteria, 8 studies were finally included. The percentage of implants in function after the first year was estimated to be 98.4 % in the maxilla and 99.2 % in the mandible. The estimates of the weighted mean ACR-percentage increased over the years up to 2.6 (SE 0.7) during the fifth year of function for the maxilla and to 9.4 (SE 8.4) for the mandible in the tenth year of function. After 10 years, the mean percentage of successful implants was estimated to be 71.1 % in the maxilla and 72.2 % in the mandible. The estimates seem to confirm the proposed, long-term progressive bone loss pattern of CaP-ceramic-coated dental implants. Within the limits of this meta-analytic approach to the literature, we conclude that: (1) published long-term success data for calcium phosphate plasma-spray-coated dental implants are limited, (2) comparison of the data is difficult due to differences in success criteria among the studies, and (3) long-term CSRs demonstrate very weak evidence for progressive complications around calcium phosphate plasma-spray-coated dental implants.

Comparative ex vivo evaluation of two electronic percussive testing devices measuring the stability of dental implants

BACKGROUND

A comparative ex vivo study was performed to determine electronic percussive test values (PTVs) measured by cabled and wireless electronic percussive testing (EPT) devices and to evaluate the intra- and interobserver reliability of the wireless EPT device.

METHODS

Forty implants were inserted into the vertebrae and forty into the pelvis of a steer, a safe distance apart. The implants were all 4.3 mm wide and 13 mm long, from the same manufacturer. PTV of each implant was measured by four different examiners, using both EPT devices, and compared. Additionally, the intra- and interobserver reliability of the wireless EPT device was evaluated.

RESULTS

Statistically significant differences (P <0.05) were observed between PTVs made by the two EPT devices. PTVs measured by the wireless EPT device were significantly higher than the cabled EPT device (P <0.05), indicating lower implant stability. The intraobserver reliability of the wireless EPT device was evaluated as excellent for the measurements in type II bone and good-to-excellent in type IV bone; interobserver reliability was evaluated as fair-to-good in both bone types.

CONCLUSION

The wireless EPT device gives PTVs higher than the cabled EPT device, indicating lower implant stability, and its inter- and intraobserver reliability is good and acceptable.

The dynamic interface: A review

The implant-to-tissue interface is an extremely dynamic region of interaction. Generally, a surgical procedure is performed on a patient to insert a foreign material into the bone, and the body is called on to “heal” the wound. The time schedule crucial for a healing process that is expected to result in restitution ad integrum must be determined with respect to the condition of the individual patient and tissue to be treated. There are various factors responsible for the formation of an adequate bone–implant interface. A comprehensive review of the response of bone to implant is described.

In situ electrochemical study of the interaction of cells with thermally treated titanium

Micromotion and fretting wear between bone and Ti-based alloys in stem and dental implants breaks the passive film and exposes the metal to the action of the complex surrounding medium, generating substantial amounts of debris and continuous Ti ion release. In this work, oxidation treatments at low temperatures (277 °C, 5 h) have been used to promote the formation of wear-corrosion resistant titanium oxide on the Ti surface. The objective of this paper has been the study of the influence of live cells on the protectiveness of the oxide formed at these low temperatures. The interaction of cells with the modified surface has been studied by scanning electron microscopy, electrochemical impedance spectroscopy, polarization curves, and x-ray photoelectron spectroscopy (XPS). The chemical composition of the thermally treated Ti surface is mainly TiO2 as anatase-rich titanium dioxide with a low concentration of hydroxyl groups and a low mean nanoroughness that could promote good cell adhesion. The electrochemical results indicate that the cells alter the overall resistance of the thermally treated Ti surfaces by decreasing the oxide resistance with time. At the same time, the anodic current increases, which is associated with cathodic control, and is probably due to the difficulty of access of oxygen to the Ti substrate. XPS reveals the presence of proteins on the surface of the treated specimens in contact with the cells and a decrease in the Ti signal associated with the extracellular matrix on the surface and the reduction of the oxide thickness.

Two-Year Success Rate of Implant-Retained Mandibular Overdentures by Novice General Dentistry Residents

The purpose of the present study was to evaluate the clinical success and patient satisfaction when dental implant–retained mandibular overdentures are placed and restored by novice general dentistry residents. A total of 50 subjects who were dissatisfied with their mandibular complete dentures were enrolled in the study. Two dental implants were placed in the anterior mandible between the mental foramina by novice general dentistry residents under the direct supervision of the principal investigator. The resident attached the denture to the implants 3 to 4 months later using locator attachments. The implant success rate was determined by measuring bone loss, mobility, pocket probing depth, and gingival and plaque indices. Subjects were asked to complete a satisfaction questionnaire with the prosthesis at 3 months, 1 year, and 2 years after overdenture delivery. A total of 100 implants were placed in the 50 study subjects. Of these, 2 implants were lost in 1 subject, and 1 subject died due to unrelated causes. Of the 48 remaining subjects, 45 have had their implants restored with overdentures. The subjects' overall satisfaction with fit and ability to chew hard foods with their mandibular overdentures improved significantly (P &lt; .05) following the denture attachment to the dental implants. We conclude that novice general dentistry residents can successfully place mandibular implants and restore them with overdentures under direct supervision, subsequently enhancing the subjects' satisfaction with their mandibular dentures.

An in vitro evaluation of the responses of human osteoblast-like SaOs-2 cells on SLA titanium surfaces irradiated by different powers of CO2 lasers

Bacterial biofilms have been identified as the primary etiological factor for the development and progression of peri-implantitis. Lasers have been shown to remove bacterial plaque from titanium surfaces effectively and can restore its biocompatibility without damaging these surfaces. Therefore, the aim of this study was to evaluate the responses (i.e., the cell viability and morphology) of human osteoblast-like SaOs-2 cells to sandblasted, large grit, and acid-etched (SLA) titanium surfaces irradiated by CO2 lasers at two different power outputs. A total of 24 SLA disks were randomly radiated by CO2 lasers at either 6 W (group 1, 12 disks) or 8 W (group 2, 12 disks). Non-irradiated disks were used as a control group (four disks). The cell viability rates of the SaOs-2 cells in the control and study groups (6 and 8 W) were 0.33 ± 0.00, 0.24 ± 0.11, and 0.2372 ± 0.09, respectively (P < 0.6). Cells with cytoplasmic extensions and spreading morphology were most prominent in the control group (141.00 ± 29.00), while in the study groups (6 and 8 W), the number of cells with such morphology was 60.40 ± 26.00 and 35.20 ± 5.40, respectively (P < 0.005). Within the limits of this study, it may be concluded that the use of CO2 lasers with the aforementioned setting parameters could not be recommended for decontamination of SLA titanium surfaces.

Nontraumatic Implant Explantation: A Biomechanical and Biological Analysis in Sheep Tibia

Preclinical research in a sheep tibia model has been conducted to evaluate the underlying mechanisms of the nontraumatic implant explantation of failed implants, which allow placing a new one in the bone bed. Twelve dental implants were placed in sheep diaphysis tibia and once osseointegrated they were explanted using a nontraumatic implant explantation approach. Implant osseointegration and explantation were monitored by means of frequency resonance, removal torque, and angle of rotation measurement. The host bone bed and the explanted implant surface were analyzed by conventional microscopy and scanning electron microscope. Results show that osseointegration was broken with an angular displacement of less than 20°. In this situation the implant returns to implant stability quotient values in the same range of their primary stability. Moreover, the explantation technique causes minimal damage to the surrounding bone structure and cellularity. This nontraumatic approach allows the straightforward replacement of failed implants and emerges as a promising strategy to resolve clinically challenging situations.

In vivo and in vitro studies of epithelial cell behavior around titanium implants with machined and rough surfaces

BACKGROUND

The surface roughness of a dental implant affects the epithelial wound healing process and may significantly enhance implant prognosis.

PURPOSE

We explored the influence of surface roughness on peri-implant epithelium (PIE) sealing and down-growth by comparing machine-surfaced (Ms) and rough-surfaced (Rs) implants.

MATERIALS AND METHODS

(1) Maxillary first molars were extracted from rats and replaced with Ms or Rs implants. (2) We also compared changes in the morphology of cultured rat oral epithelial cells (OECs) grown on Ms or Rs titanium (Ti) plates.

RESULTS

(1) After 4 weeks, the PIE around Ms and Rs implants showed a similar structure to junctional epithelium (JE). At 16 weeks, Rs implants appeared to form a weak epithelial seal at the tissue-implant interface and exhibited markedly less PIE down-growth than Ms implants but was deeper than that observed in natural teeth. (2) We observed less expression of adhesion proteins in OECs cultured on Rs plates than in cells grown on Ms plates. Additionally, cell adherence, migration, and proliferation on Rs plates were lower, whereas apoptosis was reduced on Ms plates.

CONCLUSION

Ms implants are a better choice for integration with an epithelial wound healing process.

A novel multi-phosphonate surface treatment of titanium dental implants: a study in sheep

The aim of the present study was to evaluate a new multi-phosphonate surface treatment (SurfLink^®) in an unloaded sheep model. Treated implants were compared to control implants in terms of bone to implant contact (BIC), bone formation, and biomechanical stability. The study used two types of implants (rough or machined surface finish) each with either the multi-phosphonate Wet or Dry treatment or no treatment (control) for a total of six groups. Animals were sacrificed after 2, 8, and 52 weeks. No adverse events were observed at any time point. At two weeks, removal torque showed significantly higher values for the multi-phosphonate treated rough surface (+32% and +29%, Dry and Wet, respectively) compared to rough control. At 52 weeks, a significantly higher removal torque was observed for the multi-phosphonate treated machined surfaces (+37% and 23%, Dry and Wet, respectively). The multi-phosphonate treated groups showed a positive tendency for higher BIC with time and increased new-old bone ratio at eight weeks. SEM images revealed greater amounts of organic materials on the multi-phosphonate treated compared to control implants, with the bone fracture (from the torque test) appearing within the bone rather than at the bone to implant interface as it occurred for control implants.

Effects of Er: YAG laser irradiation on wettability, surface roughness, and biocompatibility of SLA titanium surfaces: an in vitro study

The erbium: yttrium-aluminum-garnet (Er: YAG) laser has been introduced as an effective method in the decontamination of implant surfaces. Data concerning the effects of the Er: YAG laser on the biological and surface properties of titanium are conflicting. Cellular behavior is greatly affected by surface properties, including composition, roughness, wettability, and morphology of the titanium surface. The aim of this study was to investigate the influence of the Er: YAG laser on the biocompatibility, surface roughness, and wettability of sandblasted and acid-etched (SLA) titanium surfaces. Twenty-one SLA titanium disks were irradiated by the Er: YAG laser at a pulse energy of 100 mJ, with a pulse frequency of 10 Hz under water irrigation for 1 min. Cell viability, surface roughness, and wettability alterations were evaluated. Thirteen nonirradiated SLA disks were used as the control groups. Human osteoblast-like SaOs-2 cells were seeded onto the disks in culture media. Cell viability was evaluated using the methylthiazol tetrazolium assay. The surface roughness and wettability of the test and control groups were measured using profilometer and tensiometer devices, respectively. A significantly higher cell viability rate was observed in the test group (p = 0.032). The surface roughness was significantly reduced in the test group compared with the control group (p = 0.008). The surface wettability was significantly higher in the test group (p = 0.004). Within the limits of this study, the application of the Er: YAG laser with the previously described properties did not appear to have adverse effects on the biocompatibility of the SLA titanium surfaces. Application of this laser decreased the surface roughness and increased the wettability of the SLA titanium surfaces.

EFFECTS OF DENTAL IMPLANT LENGTH AND BONE QUALITY ON BIOMECHANICAL RESPONSES IN BONE AROUND IMPLANTS: A 3-D NON-LINEAR FINITE ELEMENT ANALYSIS

The aim of this study was to evaluate the influence of implant length and bone quality on the biomechanical aspects in alveolar bone and dental implant using non-linear finite element analysis. Two fixture lengths (8 and 13mm) of Frialit-2 root-form titanium implants were buried in 4 types of bone modeled by varying the elastic modulus for cancellous bone. Contact elements were used to simulate the realistic interface fixation within the implant system. Axial and lateral (buccolingual) loadings were applied at the top of the abutment to simulate the occlusal forces. The simulated results indicated that the maximum strain values of cortical and cancellous bone increased with lower bone density. In addition, the variations of cortical bony strains between 13mm and 8mm long implants were not significantly as a results of the same contact areas between implant fixture and cortical bone were found for different implant lengths. Lateral occlusal forces significantly increased the bone strain values when compared with axial occlusal forces regardless of the implant lengths and bone qualities. Loading conditions were found as the most important factor than bone qualities and implant lengths affecting the biomechanical aspects for alveolar bone and implant systems. The simulated results implied that further understanding of the role of occlusal adjustment influencing the loading directions are needed and might affect the long-term success of an implant system.