Monolithic Zirconia Single Crowns Supported by Narrow or Standard Diameter Titanium-zirconium Implants in Posterior Sites: One-year Results of a Randomized Controlled Trial.

The replacement of missing teeth with implant-supported prostheses has become a standard treatment option with reliable long-term outcomes in various clinical indications.1-6 The implant-supported single crowns, in particular, presented the most favorable outcome with a survival rate of 89.5% to 96% over a 10-year period.5,6 A notable prosthetic maintenance requirement, however, was reported irrespective of the prosthetic material used for the crown construction.1,7 Metal-ceramic restorations have been considered the gold standard when replacing single or multiple missing teeth with implant-supported fixed dental prostheses.8 A systematic review of 4363 metal-ceramic implant-supported single crowns in the anterior and posterior region reported an impressive survival rate of 98.3% over five years.9 Yet, the biologic and prosthetic complications associated with these restorations were substantial with a rate of 13.5%. In the posterior region, a recent systematic review of short-term randomized controlled trials10 reported a survival rate of 99.1% for metal-ceramic implant-supported single crowns. The reported prosthetic complications, mainly ceramic chipping, were also notable with an incidence rate of 7.6%.mIn recent years, the introduction of high-strength all-ceramic materials as well as digitaldesign and manufacturing processes, has allowed faster fabrication of more esthetic and cost effective restorations.11 Zirconia-based fixed dental prostheses on teeth and implants are now increasingly used and show 5-year cumulative survival rates of 89.4 to 100%.12 These restorations are typically made up of a zirconia framework that is veneered with a layer of glass ceramic to impart translucency for enhanced esthetics.13 However, chipping of the ceramic layer has been a lingering issue, shifting the attention toward the use of full anatomic monolithic zirconia restorations.14,15 Replacement of missing teeth with dental implants in posterior ridges with limited bone width can be surgically challenging and the notion of narrow diameter implants has been suggested.16,17 These implants were thought to offer potential advantages in terms of costeffectiveness and surgical morbidity.18,19 The literature, however, remains controversial on treatment outcomes with narrow diameter implants, particularly in posterior sites.19-21 When single tooth replacement with monolithic zirconia implant-supported single crowns in posterior sites are considered, only short to medium-term outcomes are available.22-26 The survival rates and clinical performances reported in these studies were variable. Crown survival rates between 84% and 100% were demonstrated over an observation time of one to three years, while the prosthetic complications were between 0% to 14%. In three studies,22,23,25 standard diameter titanium implants were used in premolar and molar sites to support the single crowns. The remaining two studies by Mühlemann et al. (2020) and Zumstein et al. (2023) reported the one-year and three-year outcomes, respectively, of the same cohort. In these studies, narrow titanium-zirconium (TiZr) implants of 3.3 mm diameter were exclusively utilized in molar sites. The implant and crown survival rates reported at one and three years were 97.4% and 84%, respectively. The lower survival rate observed in the report of Zumstein et al. (2023) resulted from fracture of five implants and the subsequent loss of their respective crowns. Aside from these two reports, no other information on the outcomes of monolithic zirconia single crowns supported by narrow diameter TiZr implants in posterior sites are available. The validity of this treatment, therefore, needs further investigation with well-designed clinical trials. Hence, a randomized controlled trial was undertaken to assess various implant, prosthetic, and patient-reported outcomes of monolithic zirconia single crowns supported by either narrow or standard diameter titanium-zirconium (TiZr) implants in posterior sites. The present report focuses on the one-year prosthetic results.

"I lost my first tooth here": Syrian former refugees' experiences of oral healthcare in Dunedin, New Zealand.

AIM: Oral health conditions are highly prevalent among former refugees; however, little is known about their experiences of accessing dental care. We aimed to explore Syrian former refugees' experiences of oral healthcare in New Zealand. METHOD: Thirty-nine Syrian former refugees resettled in Dunedin, New Zealand participated in nine focus group discussions. The interviews were audio-recorded, transcribed verbatim and thematically analysed. RESULTS: Almost all participants reported motivation to care for their teeth but multiple factors facilitated or hindered their ability to address their oral health needs, including financial factors, communication issues and dental care provider cultural safety. Most participants arrived with high expectations of New Zealand's health system. CONCLUSION: Oral healthcare providers and policymakers need to expect and accept their patients' past experiences and emotions, and consider their cultures, languages and backgrounds.

Bone remodelling marker expression in grafted and ungrafted sheep tooth extraction sockets: A comparative randomised study.

OBJECTIVE: To compare key markers of bone remodelling in a sheep tooth extraction model for sockets left to heal naturally or grafted with the bovine-derived xenograft Bio-Oss® covered with a collagen Bio-Gide® membrane. DESIGN: Right side premolar teeth were removed from thirty Romney-cross ewes. Standardised sockets in each sheep were randomly allocated treatments, a grafted test and an empty control. At 4-, 8- and 16-weeks sheep were euthanized and tissue collected (N = 10/group). RANK, RANKL and OPG immunohistochemical analysis was performed (n = 3). RANK, RANKL, OPG, COL1A1, TIMP3, SP7 and MSX2 mRNA expression levels were determined using RT2-qPCR assays (n = 3). RESULTS: Histologically, more new woven bone was observed in the test group at all time points. Strong RANK and RANKL expression was found in both groups; at all time points with stronger RANK staining in the test group at 8 and 16 weeks. Strong OPG staining was localized to both osteoblasts and connective tissues. RANK receptor mRNA was expressed at a lower level in the test group (-4.26-fold; p = 0.02) at 4 weeks and SP7 at 16 weeks (-2.89-fold; p = 0.04). COL1A1 and TIMP3 mRNA expression increased significantly over time in the control group (p = 0.045, F = 5.4 and p = 0.003, F = 42.2 respectively). CONCLUSION: Socket healing over time was comparable. The sheep tooth extraction model was found to be suitable for the evaluation of changes in the alveolar bone at the molecular level.

Expression of the pleiotrophin-midkine axis in a sheep tooth socket model of bone healing.

OBJECTIVE AND BACKGROUND: Resorption of alveolar bone after tooth extraction is a common problem often requiring bone grafting. The success of the grafting procedures is dependent on multiple factors including the presence of growth factors. This is the first in vivo study to investigate the role of the pleiotrophin family of cytokines in alveolar bone regeneration. This research investigated the role of the pleiotrophin-midkine (PTN-MDK) axis during osteogenesis, with and without a grafting material, after tooth extraction in a sheep model. METHODS: Thirty Romney-cross ewes were anesthetized, and all premolar teeth on the right side were extracted. The sockets were randomized to controls sites with no treatment and test sites with Bio-Oss® graft material and Bio-Gide® membrane. Samples were harvested after sacrificing animals 4, 8, and 16 weeks post-grafting (n = 10 per time-point). Tissue for qRT2 -PCR gene analysis was recovered from the socket next to the first molar using a trephine (Ø = 2 mm). Each socket was fixed, decalcified, paraffin-embedded, and sectioned. Immunohistochemistry was conducted to localize both PTN and MDK along with their receptors, protein tyrosine phosphatase receptor type Z1 (PTPRZ1), ALK receptor tyrosine kinase (ALK), and notch receptor 2 (NOTCH2). RESULTS: Within the healing sockets, high expression of genes for PTN, MDK, NOTCH2, and ALK was found at all time-points and in both grafted and non-grafted sites, while PTPRZ1 was only expressed at low levels. The relative gene expression of the PTN family of cytokines was not statistically different at the three time-points between test and control groups (p > .05). Immunohistochemistry found PTN and MDK in association with new bone, NOTCH2 in the connective tissue, and PTPRZ1 and ALK in association with cuboidal osteoblasts involved in bone formation. CONCLUSIONS: The PTN-MDK axis was highly expressed in both non-grafted and grafted sockets during osteogenesis in a sheep model of alveolar bone regeneration with no evidence that grafting significantly affected expression. The activation of NOTCH2 and PTPRZ1 receptors may be important during bone regeneration in vivo. The discovery of the PTN-MDK axis as important during alveolar bone regeneration is novel and opens up new avenues of research into these stably expressed highly active cytokines. Growth factor supplementation with PTN and/or MDK during healing may be an approach for enhanced regeneration or to initiate healing where delayed.

Dental high-speed handpiece and ultrasonic scaler aerosol generation levels and the effect of suction and air supply.

OBJECTIVE: Exposure to aerosol spray generated by high-speed handpieces (HSHs) and ultrasonic scalers poses a significant health risk to oral health practitioners from airborne pathogens. Aerosol generation varies with different HSH designs, but to date, no study has measured this. MATERIALS AND METHODS: We measured and compared aerosol generation by (1) dental HSHs with 3 different coolant port designs and (2) ultrasonic scalers with no suction, low-volume evacuation (LVE) or high-volume evacuation (HVE). Measurements used a particle counter placed near the operator's face in a single-chair, mechanically ventilated dental surgery. Volume concentrations of aerosol, totaled across a 0.3-25-µm size range, were compared for each test condition. RESULTS: HSH drilling and scaling produced significantly high aerosol levels (P < .001) with total volume concentrations 4.73×108µm3/m3 and 4.18×107µm3/m3, respectively. For scaling, mean volume of aerosol was highest with no suction followed by LVE and HVE (P < .001). We detected a negative correlation with both LVE and HVE, indicating that scaling with suction improved operator safety. For drilling, simulated cavity preparation with a 1-port HSH generated the most aerosol (P < .01), followed by a 4-port HSH. Independent of the number of cooling ports, lack of suction caused higher aerosol volume (1.98×107 µm3/m3) whereas HVE significantly reduced volume to -4.47×105 µm3/m3. CONCLUSIONS: High concentrations of dental aerosol found during HSH cavity preparation or ultrasonic scaling present a risk of infection, confirming the advice to use respiratory PPE. HVE and LVE both effectively reduced aerosol generation during scaling, whereas the new aerosol-reducing 'no air' function was highly effective and can be recommended for HSH drilling.

Zirconia versus Titanium Implants: 8-Year Follow-Up in a Patient Cohort Contrasted with Histological Evidence from a Preclinical Animal Model.

Zirconia ceramic (ZC) implants are becoming more common, but comparisons between preclinical histology and long-term clinical trials are rare. This investigation comprised (1) 8-year clinical follow-up of one-piece ZC or titanium (Ti) implants supporting full overdentures and (2) histomorphometric analysis of the same implants in an animal model, comparing implants with various surface treatments. METHODS: (1) Clinical trial: 24 completely edentulous participants (2 groups of N = 12) received 7 implants (one-piece ball-abutment ZC or Ti; maxilla N = 4, mandible N = 3) restored with implant overdentures. Outcomes after 8-years included survival, peri-implant bone levels, soft-tissue responses, and prosthodontic issues. (2) Preclinical trial: 10 New Zealand sheep received 4 implants bilaterally in the femoral condyle: Southern Implants ZC or Ti one-piece implants, identical to the clinical trial, and controls: Southern ITC® two-piece implants with the same surface or Nobel (NBC) anodised (TiUnite™) surface. %Bone-implant contact (%BIC) was measured after 12 weeks of unloaded healing. RESULTS: 8 of 24 participants (33%) of an average age of 75 ± 8 years were recalled; 21% of original participants had died, and 46% could not be contacted. 80.4% of implants survived; excluding palatal sites, 87.5% of Ti and 79% of ZC implants survived. All failed implants were in the maxilla. Three ZC implants had fractured. Bone loss was similar for Ti vs. ZC; pocket depths (p = 0.04) and attachment levels (p = 0.02) were greater for Ti than ZC implants. (1.7 ± 1.6 mm vs. 1.6 ± 1.3 mm). All implants in sheep femurs survived. %BIC was not statistically different for one-piece blasted surface Ti (80 ± 19%) versus ZC (76 ± 20%) or ITC® (75 ± 16 mm); NBC had significantly higher %BIC than ITC (84 ± 17%, p = 0.4). CONCLUSION: Short-term preclinical results for ZC and Ti one-piece implants showed excellent bone-implant contact in unloaded femoral sites. This differed from the long-term clinical results in older-aged, edentulous participants. While ZC and Ti implants showed equivalent performance, the risks of peri-implantitis and implant loss in older, completely edentulous patients remain a significant factor.

Meeting the challenges and clinical requirements for dental regeneration; the New Zealand experience.

Disease and trauma leading to tooth loss and destruction of supporting bone is a significant oral handicap, which may be addressed through surgical therapies that aim to regenerate the lost tissue. Whilst complete regeneration of teeth is still aspirational, regeneration of supporting structures (dental pulp, cementum, periodontal ligament, bone) is becoming commonplace, both for teeth and for titanium dental implants that are used to replace teeth. Most grafting materials are essentially passive, however the next generation of oral regenerative devices will combine non-antibiotic antimicrobials and/or osteogenic or inductive factors and/or appropriate multipotential stem cells. The review gives an overview of the approaches taken, including fabrication of novel scaffolds, incorporation of growth factors and cell-based therapies, and discusses the preclinical animal models we employ in the development pathway.

Is titanium-zirconium alloy a better alternative to pure titanium for oral implant? Composition, mechanical properties, and microstructure analysis.

INTRODUCTION: Titanium (Ti) is widely accepted as a biomaterial for orthopaedic and dental implants, primarily due to its capacity to integrate directly into the bone and its superior corrosion resistance. It has been suggested that titanium-zirconium alloy (TiZr), with 13-17% of zirconium, has better mechanical properties than pure Ti, but there are very few published studies assessing the suitability of TiZr for high-load- bearing implants. This study aimed to compare the mechanical properties and microstructures of TiZr and commercially pure titanium (Ti). METHODOLOGY: Pure Ti and TiZr alloy discs were prepared and subjected to characterisation by nanoindentation, electron dispersive spectroscopy (EDS), X-ray diffraction (XRD), and electron backscatter diffraction (EBSD). RESULTS: The TiZr alloy was found to have significantly lower elastic modulus value (p < 0.0001) and greater hardness than Ti (p < 0.05). The EDS results confirmed the presence of Zr (13-17%) in the TiZr alloy, with XRD and EBSD images showing microstructure with the alpha phase similar to commercially available Ti. CONCLUSION: The lower elastic modulus, higher hardness, presence of alpha phase, and the finer grain size of the TiZr alloy make it more suitable for high-load-bearing implants compared to commercially available Ti and is likely to encourage a positive biological response.

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.

Formulation of a Semisolid Emulsion Containing Leptospermum scoparium Essential Oil and Evaluation of In Vitro Antimicrobial and Antibiofilm Efficacy.

Manuka oil, an essential oil derived from the Leptospermum scoparium, has been traditionally used for wound care and as a topical antibacterial, antifungal, and anti-inflammatory. However, the essential oil is not well retained at mucosal sites, such as the oral cavity, where the benefits of the aforementioned properties could be utilized toward the treatment of persistent biofilms. Within this study, L. scoparium essential oil was incorporated into a semisolid emulsion for improved delivery. The safety profile of L. scoparium essential oil on human gingival fibroblasts was determined via cell viability, cytotoxicity, and caspase activation. The minimal bactericidal concentration of L. scoparium essential oil was determined, and the emulsion's antibiofilm effects visualized using confocal laser scanning microscopy. L. scoparium essential oil demonstrated a lower IC50 (0.02% at 48 h) when compared to the clinical control chlorhexidine (0.002% at 48 h) and displayed lower cumulative cytotoxicity. Higher concentrations of L. scoparium essential oil (≥ 0.1%) at 6 h resulted in higher caspase 3/7 activation, suggesting an apoptotic pathway of cell death. A minimal bactericidal concentration of 0.1% w/w was observed for 6 oral bacteria and 0.01% w/v for Porphyromonas gingivalis. Textural and rheometric analysis indicated increased stability of emulsion with a 1 : 3 ratio of L. scoparium essential oil: Oryza sativa carrier oil. The optimized 5% w/w L. scoparium essential oil emulsion showed increased bactericidal penetrative effects on Streptococci gordonii biofilms compared to oil alone and to chlorhexidine controls. This study has demonstrated the safety, formulation, and antimicrobial activity of L. scoparium essential oil emulsion for potential antibacterial applications at mucosal sites.

Ultrastructure and properties of primary carious molars treated using the Hall Technique.

BACKGROUND: The Hall Technique (HT) is a method of restoring decayed primary teeth using stainless steel crowns (SSCs) without tooth preparation, caries removal, or local anaesthetic. AIM: To investigate the ultrastructural, biomechanical, and chemical characteristics of teeth managed with the Hall Technique in comparison with conventional SSC (controls). DESIGN: Twelve HT-treated primary molars and four controls were analysed. Teeth were dehydrated in ethanol, embedded in methylmethacrylate, mesio-distally sectioned, X-rayed, mounted, and polished. Biomechanical, ultrastructural, and chemical characterisation was performed for carious lesion and sound areas of each specimen. RESULTS: Pre-treatment and post-treatment X-rays showed evidence of little to no caries progression over time. In carious lesions, mean hardness and elastic modulus values were lower in HT-treated teeth than in controls. In both controls and HT-treated teeth, carious lesions had the lowest %wt of Ca and P of all tissues sampled. CONCLUSIONS: Although the retained carious tissue was biomechanically more compromised in HT-treated teeth, the Ca and P values were higher than reported elsewhere for carious lesions in primary molars, suggesting remineralisation may have occurred in caries in HT-treated teeth. Future investigations will help elucidate the processes involved with carious lesion arrest under SSC.

Predicting peri-implant disease: Chi-square automatic interaction detection (CHAID) decision tree analysis of risk indicators.

BACKGROUND: Further validation of the risk indicators / predictors for peri-implant diseases is required to allow clinicians and patients to make informed decisions and optimize dental implant treatment outcomes. The aim of this study was to build prediction models, using Chi-square automatic interaction detection (CHAID) analysis, to determine which systemic-, patient-, implant-, site-, surgical- and prostheses-related risk indicators had more impact on the onset of peri-implant diseases. METHODS: A retrospective analysis of 200 patients who received implant-supported prostheses between 1998 and 2011 was conducted to evaluate the prevalences and risk indicators for peri-implant mucositis and peri-implantitis. The data were further analyzed using CHAID to produce two predictive models. RESULTS: The prevalence of peri-implant mucositis was 20.2% and 10.2% for patients and implants, respectively, while the prevalence of peri-implantitis was 10.1% at the patient level and 5.4% at the implant level. CHAID decision tree analysis identified three predictors (history of treated periodontitis, absence of regular supportive peri-implant maintenance, and use of bone graft) for peri-implant mucositis and three predictors (smoking, absence of regular supportive peri-implant maintenance, and placement of ≥2 implants) for peri-implantitis. CONCLUSIONS: Within the limitations of this study, CHAID decision tree analysis identified the most plausible risk indicators and provided two predictive models for use in a particular university setting that would allow early detection and ensure appropriate care and maintenance of patients at high risk of peri-implant diseases.

Stability of tapered and parallel-walled dental implants: A systematic review and meta-analysis.

BACKGROUND: Clinical trials have suggested that dental implants with a tapered configuration have improved stability at placement, allowing immediate placement and/or loading. The aim of this systematic review and meta-analysis was to evaluate the implant stability of tapered dental implants compared to standard parallel-walled dental implants. MATERIALS AND METHODS: Applying the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement, randomized controlled trials (RCTs) were searched for in electronic databases and complemented by hand searching. The risk of bias was assessed using the Cochrane Collaboration's Risk of Bias tool and data were analyzed using statistical software. RESULTS: A total of 1199 studies were identified, of which, five trials were included with 336 dental implants in 303 participants. Overall meta-analysis showed that tapered dental implants had higher implant stability values than parallel-walled dental implants at insertion and 8 weeks but the difference was not statistically significant. Tapered dental implants had significantly less marginal bone loss compared to parallel-walled dental implants. No significant differences in implant failure rate were found between tapered and parallel-walled dental implants. CONCLUSIONS: There is limited evidence to demonstrate the effectiveness of tapered dental implants in achieving greater implant stability compared to parallel-walled dental implants. Superior short-term results in maintaining peri-implant marginal bone with tapered dental implants are possible. Further properly designed RCTs are required to endorse the supposed advantages of tapered dental implants in immediate loading protocol and other complex clinical scenarios.

Wool-derived keratin hydrogel enhances implant osseointegration in cancellous bone.

AIM: This study investigated whether a keratin hydrogel derived from wool enhances ossointegration of dental implants, using a cancellous bone model in sheep. METHOD: Ten female sheep received one dental implant per hind leg in the distal femoral condyles. Test implants were coated with 1 mL of keratin hydrogel containing sulphonated keratin and hydroxyapatite; control implants remained uncoated; implants were not functionally loaded axially. Biomechanical stability was tested with resonance frequency analysis (RFA) at placement and euthanasia. Animals were sacrificed after 4 weeks and resin-embedded histomorphometry performed. FINDINGS: Bone appeared denser and more mature around the keratin-treated test implants. Average % bone-implant contact was significantly increased for the test (58.1 ± 4.6 [SD]%) compared to control implants (34.4 ± 7.5%) (p = 0.01). RFA values were lower for control (76.5 ± 4.2 ISQ) than test implants (80.4 ± 1.4) after 4 weeks (p = 0.04). CONCLUSION: the increase in osseointegration found in this model suggests that keratin hydrogel has the potential to enhance the successful osseointegration of dental implants placed into poor quality bone. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2447-2454, 2018.

Piezoelectric versus conventional implant site preparation: A systematic review and meta-analysis.

BACKGROUND: The use of a piezoelectric device (PED) for implant site preparation (ISP) has been introduced to overcome the limitations of using conventional drills (CDs). With little and inconsistent information in the literature regarding their efficiency for preparing implant osteotomies, the objective of this systematic review was to compare the use of CDs to PEDs for ISP with regard to implant stability values, marginal bone level changes, operating time, and dental implant failure rate. METHODS: The systematic review was prepared according to the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The literature was searched for studies that assessed the use of CDs and PEDs for ISP. The Cochrane Collaboration risk of bias tool was used to evaluate the selected studies and meta-analyses were performed using statistical software. RESULTS: A total of 755 citations were identified. Of these, 4 studies with 178 implant osteotomies in 80 participants were included. The pooled estimates for the implant stability showed significant differences between the 2 surgical techniques in favor of PEDs at baseline, 8 and 12 weeks. A statistically significant difference in the operating time was also shown between the 2 techniques with more time required using PED. The differences in marginal bone level changes or implant failure rate were not statistically significant. CONCLUSIONS: With the limitations of this review in mind, PEDs appear to be a viable alternative to traditional drilling techniques for ISP. With the exception of prolonged operating time associated with the use of PEDs, both techniques were comparable in terms of the marginal bone level changes and the risk of implant failure. The favorable influence of the implant stability pattern related to the use of PEDs on the predictability of immediate and early loading protocols need to be confirmed in future studies.

The One Abutment-One Time Protocol: A Systematic Review and Meta-Analysis.

BACKGROUND: The use of definitive abutments (DAs) at time of implant placement has been introduced to overcome limitations of dis/reconnection of healing/provisional abutments (PAs). With little and inconsistent information in the literature regarding the effectiveness of using DAs, the aim of this systematic review is to examine marginal bone and soft tissue level changes, technical and biologic complications, and implant failure rate associated with use of DAs and PAs. METHODS: This systematic review was prepared according to guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and online trial registers were searched for studies comparing use of DAs and PAs. The Cochrane Collaboration risk of bias tool was used to assess selected studies, and meta-analyses were performed using statistical software. RESULTS: A total of 1,124 citations were identified. Of these, seven trials with 363 dental implants in 262 participants were included in the analysis. Pooled estimates for marginal bone level changes showed significant differences between the two prosthetic techniques in favor of using DAs. No significant differences were found in soft tissue level changes, technical and biologic complications, or implant failure rate. CONCLUSIONS: Within the limitations of this review, DAs appear to be a viable alternative to PAs at time of implant placement. However, favorable changes in peri-implant marginal bone level associated with use of DAs should be viewed with caution as its clinical significance is still uncertain.

Periodontal Application of Manuka Honey: Antimicrobial and Demineralising Effects In Vitro.

Background. Topical application of manuka honey is effective in the treatment of burns and soft-tissue infections. The aim of this study was to assess the antibacterial activity of manuka honey against plaque-associated bacteria in vitro in order to evaluate the potential application as an adjunct to periodontal treatment. Materials and Methods. The minimum bacteriostatic and bactericidal concentrations (MIC and MBC) of manuka honey were compared to those of white clover honey against a variety of plaque-associated bacteria, at the natural and neutral pH. Dissolved calcium was measured following incubation of honeys with hydroxyapatite (HA) beads to assess their potential to demineralise oral hard tissues. Results. Both honeys inhibited most tested oral bacteria at similar MIC/MBC, but Streptococcus mutans was comparatively resistant. The honeys at pH neutral had little effect on antimicrobial activity. Incubation of HA beads in honey solutions resulted in pH-dependent calcium dissolution, and inoculation with S. mutans promoted further demineralisation by both types of honey. Conclusion. Manuka honey is antimicrobial towards representative oral bacteria. However, the relative resistance of S. mutans in association with the high concentrations of fermentable carbohydrates in honey and the direct demineralising effect at natural pH mitigate against the application of honey as an adjunct in the treatment of periodontal disease.

Implications of Wear at the Titanium-Zirconia Implant-Abutment Interface on the Health of Peri-implant Tissues.

PURPOSE: To investigate the presence of metallic particles in the peri-implant mucosa around titanium dental implants after 5 years of loading using single-implant crowns with respect to clinical signs of peri-implant inflammation. MATERIALS AND METHODS: Sixteen participants from an ongoing, prospective, single-arm clinical trial who had received titanium dental implants restored with single maxillary crowns veneered to zirconia abutments were available for the study. Exfoliative cytology samples were obtained from the peri-implant tissues and contralateral tooth sites using microbrushes and were evaluated by means of light microscopy (LM), scanning electron microscopy, and energy-dispersive spectroscopy (EDS). Trace elemental analysis was also carried out on the microbrushes using inductively coupled plasma mass spectrometry. Peri-implant and periodontal parameters (plaque, bleeding, attachment level, radiographic bone levels) were recorded. RESULTS: Titanium particles were found in both the single-implant crown and contralateral natural tooth sites. LM and EDS analyses showed significantly higher numbers of Ti particles at the implant-abutment interfaces (mean = 14.168; SD = 2.36) and in the internal aspects of peri-implant mucosa in contact with the prostheses (mean = 4.438; SD = 2.22) when compared with other test and control areas. Mean probing depths were ≤ 3 mm, and no differences were found in plaque or bleeding on probing between implant and tooth sites. Median bone levels were within the normal range for both implant (mesial: 0.5 mm; distal: 0.8 mm) and tooth (mesial: 1.5 mm; distal: 1.8 mm) sites. CONCLUSION: Loading of single-implant zirconia crowns can cause the release of Ti particles because of functional wear at the implant-abutment level. The presence of these metal particles in the peri-implant area did not appear to affect peri-implant health in this patient group.

The effect of hydrothermal spark discharge anodization in the early integration of implants in sheep sinuses.

OBJECTIVES: Spark discharge anodic oxidation forms a porous oxide film on titanium implant surfaces, which may increase surface roughness and enhance early osseointegration. This study aimed to clinically and histomorphometric compare commercially-available sandblasted (RBM) implants, treated with hydrothermal anodization and placed into an animal maxillary sinus model. MATERIALS AND METHODS: Thirty 3.75 mm × 8.5 mm threaded titanium implants were placed into the maxillary sinuses of 10 sheep via an external approach, with three test groups and 10 implants per group: right side, Control = CP-titanium with RBM surface, Test group 1 = CP-titanium with RBM + anodized surface; left side, Test group 2 = Ti-6Al-7Nb with RBM + anodized surface. Schneiderian membranes were elevated but not bone grafted. Resonant frequency analysis (RFA) was measured at surgery. Animals were sacrificed after 1 month unloaded healing. Resin-embedded undemineralized ground-sections were digitised, and mean bone-implant contact (% BIC) was measured bilaterally for the best-three consecutive threads. RESULTS: Seven of 30 implants showed signs of failure. RFA was low at placement but did not differ between the groups (group mean ISQ values ranged from 23 to 35; χ(2)  = 0.37). RFA was not repeated at sacrifice due to implant instability. Histomorphometric analysis showed % BIC was highest for control (34.8 ± 15.7), followed by Test 1 (29.6 ± 18.1) and Test 2 implants (23.3 ± 22.7), but this difference was not statistically significant (χ(2)  = 0.3). DISCUSSION AND CONCLUSIONS: Early integration of RBM implants placed into thin maxillary sinus walls was not enhanced by hydrothermal anodization of implant surfaces. This may be related to the initial low stability of the implants and the relatively short healing period. However, non-anodized RBM surfaces showed promising results, with % BIC values comparable to the best estimates of other studies using sinus grafting. Whether the modification of the implant surfaces through anodization with simultaneous sinus grafting would promote enhanced early osseointegration, is a subject of future research.

Implant-based three-dimensional superimposition of the growing mandible in a rabbit model.

BACKGROUND: The reliable assessment of craniofacial morphological changes during growth requires invariant regions for image registration. As these regions have not yet been identified in three dimensions, intra-osseous implants are required as fiducial markers for the reliable assessment of three-dimensional (3D) mandibular growth changes. The objective of this study was to develop an animal model for the assessment of the 3D morphological changes of the mandible during growth, using implants as fiducial markers. MATERIALS AND METHODS: Titanium implants were placed in the body of the mandible of six New Zealand White rabbits. Cone beam computed tomography (CBCT) scans were taken 1-week following implant placement and after an additional 8-weeks of growth. Segmentations of CBCT images were exported into custom-made scripts, implant centroids were identified, implant stability during growth calculated, and the segmented mandibles were registered on the implant centroids. RESULTS: The buccal cortical bone of the body of the mandible was stable during growth and suitable for fiducial marker placement. Bilateral implants resulted in more accurate rigid registration of the growing rabbit mandible than only unilateral implants. 3D mandibular growth changes were visualised by means of semi-transparencies. CONCLUSIONS: This animal model appears to be feasible for the assessment of the 3D morphological changes occurring during mandibular growth. To the best of our knowledge this is the first time that the implant superimposition method has been combined with 3D imaging to accurately reveal mandibular growth changes.