Accuracy of implant impression techniques with a scannable healing abutment.

STATEMENT OF PROBLEM: Scannable healing abutments are a convenient option to facilitate impression making for implant-supported restorations. However, studies evaluating the accuracy of the impression technique with scannable healing abutments are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the accuracy of implant impression techniques with scannable healing abutments. MATERIALS AND METHODS: A partially edentulous mandibular dentiform model was fabricated with an epoxy resin, and implants were placed in the mandibular right second premolar and first molar areas. A maxillary dentiform model was then fabricated, and both models were mounted on an articulator. Scan data were obtained from the mounted models and set as the reference scans. The experimental models were divided into 4 groups (n=10). The conventional pick-up impression technique and definitive casts were used in group CI. The scan data from the definitive casts were obtained with a 3D model scanner. An intraoral scanner with a digital body scan was used in group DS. Group MS yielded definitive casts with dual-arch impressions with scannable healing abutments. The fabricated definitive casts were mounted and scanned with a 3D cast scanner. Intraoral scanning with scannable healing abutments was used in group IS. In all 4 groups, the interarch relationship in the maximum intercuspal position was obtained by scanning the facial aspect. The center of the implant head was set as a measurement point for linear intra-arch deviations and implant angle deviations. The mesiopalatal cusp tip of the maxillary right first molar was used to calibrate the linear interarch deviations. The data obtained from each group were compared with the data from the reference scan. As the data were not normally distributed, the Kruskal-Wallis test and Bonferroni correction were used for the analysis (α=.05). RESULTS: Group MS exhibited significantly higher deviations in linear intra-arch and implant angles compared with the other groups (P<.05). No significant difference was found between the groups in linear interarch deviations (P>.05). CONCLUSIONS: The accuracy of intraoral scanning with scannable healing abutments was comparable with that of conventional pick-up impression techniques and digital scans with scan bodies. However, model scanning with scannable healing abutments may not be clinically acceptable for implant impressions.

Is implant surgery a risk factor for osteonecrosis of the jaw in older adult patients with osteoporosis? A national cohort propensity score-matched study.

OBJECTIVES: This study aimed to investigate the association between dental implant therapy and osteonecrosis of the jaw (ONJ) in osteoporotic patients and the relationship between tooth extraction, dental implantation, and ONJ. MATERIAL AND METHODS: This retrospective cohort study used the Customized Health Information Data from the National Health Insurance Corporation in South Korea. The study population included patients older than 70 years with a history of osteoporosis; the cases included patients who had undergone dental implant surgery between July 2014 and July 2016 with specific procedure codes. The case and control cohorts were stratified by tooth extraction because it was the strongest risk factor to consider in this study. Each group of patients was matched using the propensity score. To investigate the relationship between dental implants and ONJ, a Cox proportional hazard model was applied to socio-economic factors, comorbidities, and bisphosphonates (BPs). All analyses were conducted using SAS statistical software. RESULTS: Based on the fully adjusted model, the propensity score-matched osteoporosis patients with dental implants had a 0.51 times hazard ratio of osteonecrosis. On the contrary, tooth extraction was associated with a higher risk of ONJ (HR = 5.89). The patients with rheumatoid arthritis (RA) and those using BPs had a higher HR, respectively, 6.80 and 4.09 HR (p < .001). CONCLUSIONS: Dental implantation was not a risk factor and patients with implants show rather lower ratios. However, older osteoporotic Korean patients who had undergone tooth extraction had higher risks of ONJ. A significantly higher risk of ONJ was associated with RA and BPs as well.

A two-stage surgical approach to the treatment of severe peri-implant defect: a 30-month clinical follow-up report.

With the advance of dental implant technology and the consequential increase in its success rate, the implant has become a highly predictable treatment method. Despite this, related complications are on the rise, with peri-implant mucositis and peri-implantitis being the most commonly observed. As in the case of conventional periodontitis, many patients experience peri-implant mucositis and peri-implantitis. In this case presentation, extensive bone loss occurred around the implant due to peri-implantitis, and the infection was first treated by applying chlorhexidine-soaked gauze and topical antibiotics. Then the guided bone regeneration procedure was performed using a bovine bone material and a collagen membrane, which resulted in the recovery of the lesion. With follow-ups of the healing process for 30 months, a successful outcome was observed that is reported herein.

Topographical and crystalline change on surface by sandblasting improve flexural and shear bond strength of niobia-modified yttria-stabilized tetragonal zirconia polycrystal.

This study aimed to investigate the effects of sandblasting on the physical properties and bond strength of two types of translucent zirconia: niobium-oxide-containing yttria-stabilized tetragonal zirconia polycrystals ((Y, Nb)-TZP) and 5 mol% yttria-partially stabilized zirconia (5Y-PSZ). Fully sintered disc specimens were either sandblasted with 125 µm alumina particles or left as-sintered. Surface roughness, crystal phase compositions, and surface morphology were explored. Biaxial flexural strength (n=10) and shear bond strength (SBS) (n=12) were evaluated, including thermocycling conditions. Results indicated a decrease in flexural strength of 5Y-PSZ from 601 to 303 MPa upon sandblasting, while (Y, Nb)-TZP improved from 458 to 544 MPa. Both materials significantly increased SBS after sandblasting (p<0.001). After thermocycling, (Y, Nb)-TZP maintained superior SBS (14.3 MPa) compared to 5Y-PSZ (11.3 MPa) (p<0.001). The study concludes that (Y, Nb)-TZP is preferable for sandblasting applications, particularly for achieving durable bonding without compromising flexural strength.

Review and Update of the Risk Factors and Prevention of Antiresorptive-Related Osteonecrosis of the Jaw.

Antiresorptive-related osteonecrosis of the jaw (ARONJ) is a rare but serious adverse event of bisphosphonate or denosumab administration; it is associated with severe pain and a deteriorated quality of life. Since its first report in 2003, there have been many studies on its definition, epidemiology, pathophysiology, diagnosis, and treatment. Nevertheless, the epidemiology and mechanisms underlying this condition have not yet been fully delineated and several risk factors are known. Moreover, as there is no effective treatment currently available for osteonecrosis of the jaw, prevention is essential. Furthermore, close cooperation between prescribing physicians and dentists is important. The aim of this review was to provide up-to-date information regarding the risk factors and prevention of ARONJ from a physician's perspective.

Incidence of and risk for osteonecrosis of the jaw in Korean osteoporosis patients treated with bisphosphonates: A nationwide cohort-study.

PURPOSE: To estimate the incidence of osteonecrosis of the jaw (ONJ) in patients treated with bisphosphonates (BPs) and to identify clinical risk factors that increase the risk for ONJ in Korean osteoporosis patients. METHODS: We used data acquired from the Korean National Health Insurance Service. Among 2,140,149 participants with osteoporosis in 2012, we selected 164,926 new BP users and 164,926 age- and sex-matched control subjects. The control group included only patients with no prescriptions for BPs between January 1, 2011, and December 31, 2016. Participants were followed for 4 years. RESULTS: Over the 4-year follow-up period, the cumulative incidence rates of ONJ were 20.9 and 6.9 per 100,000 person-years in the BP and control groups, respectively. The BP group had an increased risk for ONJ compared to the control group after adjusting for multiple variables (hazard ratio [HR] 3.72, 95% CI 2.70-5.11). Advanced age (≥70 years), comorbid diseases such as diabetes, hypertension, and rheumatoid arthritis (RA) were independent risk factors for the development of ONJ. In addition, tooth extraction (HR 9.85), gingivitis, and periodontal disease (HR 4.78) were strongly associated with ONJ. CONCLUSIONS: ONJ incidence was 21 per 100,000 person-years in osteoporosis patients receiving bisphosphonates. Clinical factors including advanced age, diabetes, RA, dental disease, as well as BP use were significantly associated with ONJ.

Medication Related Osteonecrosis of the Jaw: 2021 Position Statement of the Korean Society for Bone and Mineral Research and the Korean Association of Oral and Maxillofacial Surgeons.

Antiresorptives are the most widely prescribed drugs for the treatment of osteoporosis. They are also used in malignant bone metastases, multiple myeloma, and Paget's disease, and provide therapeutic efficacy on those diseases. However, it was reported that the occurrence of osteonecrosis of the jaw (ONJ) could be related to antiresorptive exposures, and there have been many cases regarding this issue. Therefore, a clearer definition and treatment guidelines were needed for this disease. The American Society for Bone and Mineral Research and the Amnerican Association of Oral and Maxillofacial Surgeons reported statements on bisphosphonate-related ONJ (BRONJ), and a revised version was recently presented. In the revised edition, the diagnosis BRONJ was changed to medication-related ONJ (MRONJ), which reflects consideration of the fact that ONJ also occurs for denosumab, a bone resorption inhibitor of the receptor activator of the nuclear factor-κB ligand antibody family, and bevacizumab, an anti-angiogenesis inhibitor. The Korean Society for Bone and Mineral Research and the Korean Association of Oral and Maxillofacial Surgeons had collectively formed a task force for the preparation of an official statement on MRONJ based on a previous position paper in 2015. The task force reviewed current knowledge and coordinated dental and medical opinions to propose the guideline customized for the local Korean situation.

Preventive effects of tonsil-derived mesenchymal stem cells on osteoradionecrosis in a rat model.

BACKGROUND: The purpose of this study was to investigate the effects of tonsil-derived mesenchymal stem cells (MSCs) on osteoradionecrosis (ORN). METHOD: We generated a mandibular ORN rat model using a combination of 20-Gy single-dose irradiation and tooth extraction. Study groups were negative control (tooth extraction only), ORN group (irradiation, tooth extraction), Matrigel-1 group (Matrigel; BD Biosciences, San Jose, CA; irradiation, Matrigel application immediately after tooth extraction), tonsil-derived MSC-1 group (irradiation, tonsil-derived MSC application immediately after tooth extraction), Matrigel-4 group (irradiation, Matrigel application 4 weeks after tooth extraction), and tonsil-derived MSC-4 group (irradiation, tonsil-derived MSC application 4 weeks after tooth extraction). RESULT: Bone mineral density was significantly lower in the ORN group than in the negative control group. The tonsil-derived MSC-1 group showed significantly higher bone mineral density than did the ORN and tonsil-derived MSC-4 groups. CONCLUSION: A single 20-Gy dose of irradiation combined with tooth extraction successfully generated ORN in the rat model. The tonsil-derived MSCs can be effective for bone regeneration in ORN, particularly when applied immediately after dentoalveolar trauma or surgery.

Standardizing the evaluation criteria on treatment outcomes of mandibular implant overdentures: a systematic review.

PURPOSE: The aim of this review was to analyze the evaluation criteria on mandibular implant overdentures through a systematic review and suggest standardized evaluation criteria. MATERIALS AND METHODS: A systematic literature search was conducted by PubMed search strategy and hand-searching of relevant journals from included studies considering inclusion and exclusion criteria. Randomized clinical trials (RCT) and clinical trial studies comparing attachment systems on mandibular implant overdentures until December, 2011 were selected. Twenty nine studies were finally selected and the data about evaluation methods were collected. RESULTS: Evaluation criteria could be classified into 4 groups (implant survival, peri-implant tissue evaluation, prosthetic evaluation, and patient satisfaction). Among 29 studies, 21 studies presented implant survival rate, while any studies reporting implant failure did not present cumulative implant survival rate. Seventeen studies evaluating peri-implant tissue status presented following items as evaluation criteria; marginal bone level (14), plaque Index (13), probing depth (8), bleeding index (8), attachment gingiva level (8), gingival index (6), amount of keratinized gingiva (1). Eighteen studies evaluating prosthetic maintenance and complication also presented following items as evaluation criteria; loose matrix (17), female detachment (15), denture fracture (15), denture relining (14), abutment fracture (14), abutment screw loosening (11), and occlusal adjustment (9). Atypical questionnaire (9), Visual analog scales (VAS) (4), and Oral Health Impact Profile (OHIP) (1) were used as the format of criteria to evaluate patients satisfaction in 14 studies. CONCLUSION: For evaluation of implant overdenture, it is necessary to include cumulative survival rate for implant evaluation. It is suggested that peri-implant tissue evaluation criteria include marginal bone level, plaque index, bleeding index, probing depth, and attached gingiva level. It is also suggested that prosthetic evaluation criteria include loose matrix, female detachment, denture fracture, denture relining, abutment fracture, abutment screw loosening, and occlusal adjustment. Finally standardized criteria like OHIP-EDENT or VAS are required for patient satisfaction.

Recruitment and enrollment in a randomized clinical trial of mandibular two-implant overdenture.

PURPOSE: The purpose of this study was to evaluate the effectiveness of a promotion campaign for subject recruitment and selection, and reasons of withdrawal from a prospective clinical trial of mandibular two-implant supported overdenture. MATERIALS AND METHODS: The subjects of this study were participants in a randomized controlled clinical trial for investigating prognosis of implants and overdentures with attachments. Recruited subjects were classified by gender, age, and participation motives. Withdrawal rate of the participants before and after enrollment were evaluated. RESULTS: 177 patients were recruited and 51 patients were enrolled for the trial. Among them, 40 participants eventually took part in the trial. 116 subjects (65.5%) were recruited by advertisement and 61 (34.5%) were referred by patients of the hospital or local clinics. Regarding recruitment effectiveness, newspaper recruited the largest number of participants. With respect to referral patients, the proportion of our hospital patients was higher (37/61). Subjects in their 70s comprised the largest proportion (22/51). The male to female ratio was similar (25:26). Final withdrawal rate of all subjects were 74.0%. Among the reasons for withdrawal from enrollment (n=126) presence of remaining teeth and lack of motivation were the most common reasons. CONCLUSION: To facilitate recruitment of clinical trial subjects and improve enrollment rate, it is important to obtain a sufficient number of researchers, perform promotion activity with diverse strategies, cooperate with local dentists, increase the research funding, and alleviate subjects' fear against clinical trials by thorough consultation.

Effect of span length on the fit of zirconia framework fabricated using CAD/CAM system.

PURPOSE: The purpose of this study was to evaluate the effect of the span length on the fit of zirconia framework fabricated using CAD/CAM system. MATERIALS AND METHODS: Abutments for single, 4-unit and 6-unit fixed partial prostheses were fabricated. Ten zirconia frameworks were fabricated for each group. The marginal and internal gap were presented by means of replica technique and measured by measuring microscope (AXIO®, Carl Zeiss, Rochester, NY) and software (I-solution®, IMT i-solution Inc., Vancouver, BC, Canada). The results were statistically analyzed by multivariate analysis test and Dunnett T3 test for post hoc test (α=.05). RESULTS: There were statistically significant differences at 2, 4, 7, 8 points (mesio-distal section) and b, d, e, f, g (labio-lingual section). In some marginal reference points of 6-unit group (P<.05), the marginal gap were larger than 120 µm. CONCLUSION: Span length of zirconia core may have an influence on marginal and internal fit. Within the limitation of this study, the increase of span length of zirconia framework of 6 or more-unit fixed partial denture may decrease the marginal and internal fit.

Attachment systems for mandibular implant overdentures: a systematic review.

PURPOSE: The aim of this systematic review was to address treatment outcome according to attachment systems for mandibular implant overdentures in terms of implant survival rate, prosthetic maintenance and complications, and patient satisfaction. MATERIALS AND METHODS: A systematic literature search was conducted using PubMed and hand searching of relevant journals considering inclusion and exclusion criteria. Clinical trial studies on mandibular implant overdentures until August, 2010 were selected if more than one type of overdenture attachment was reported. Twenty four studies from 1098 studies were finally included and the data on implant survival rate, prosthetic maintenance and complications, patient satisfaction were analyzed relative to attachment systems. RESULTS: Four studies presented implant survival rates (95.8 - 97.5% for bar, 96.2 - 100% for ball, 91.7% for magnet) according to attachment system. Ten other studies presented an implant survival rate ranging from 93.3% to 100% without respect to the attachment groups. Common prosthetic maintenance and complications were replacement of an assay for magnet attachments, and activation of a matrix or clip for ball or bar attachments. Prosthetic maintenance and complications most commonly occurred in the magnet groups. Conflicting findings were found on the rate of prosthetic maintenance and complications comparing ball and bar attachments. Most studies showed no significant differences in patient satisfaction depending upon attachment systems. CONCLUSION: The implant survival rate of mandibular overdentures seemed to be high regardless attachment systems. The prosthetic maintenance and complications may be influenced by attachment systems. However patient satisfaction may be independent of the attachment system.

Number of implants for mandibular implant overdentures: a systematic review.

PURPOSE: The aim of this systematic review is to address treatment outcomes of Mandibular implant overdentures relative to implant survival rate, maintenance and complications, and patient satisfaction. MATERIALS AND METHODS: A systematic literature search was conducted by a PubMed search strategy and hand-searching of relevant journals from included studies. Randomized Clinical Trials (RCT) and comparative clinical trial studies on mandibular implant overdentures until August, 2010 were selected. Eleven studies from 1098 studies were finally selected and data were analyzed relative to number of implants. RESULTS: Six studies presented the data of the implant survival rate which ranged from 95% to 100% for 2 and 4 implant group and from 81.8% to 96.1% for 1 and 2 implant group. One study, which statistically compared implant survival rate showed no significant differences relative to the number of implants. The most common type of prosthetic maintenance and complications were replacement or reattaching of loose clips for 2 and 4 implant group, and denture repair due to the fracture around an implant for 1 and 2 implant groups. Most studies showed no significant differences in the rate of prosthetic maintenance and complication, and patient satisfaction regardless the number of implants. CONCLUSION: The implant survival rate of mandibular overdentures is high regardless of the number of implants. Denture maintenance is likely not inflenced substantially by the number of implants and patient satisfaction is typically high again regardless os the number of implants.

Implant surface factors and bacterial adhesion: a review of the literature.

The microbiota that forms on implant surfaces placed in the human body can be highly resistant to antimicrobial agents and in some cases cause life-threatening infections. Consequently, to limit bacterial attachment to these surfaces and thereby minimize the risk of implant infection, the process of biofilm formation and bacterial attachment must be well-understood. The oral environment is considered to be an excellent model for research into biofilm formation and implant infection, accounting for many studies carried out in the field of dental medicine. Those studies show that the roughness, free energy, and material characteristics of the implant surface largely determine initial bacterial adhesion. This article reviews the relevant literature on these aspects of biofilm formation.

One-pot synthesis and surface modifications of organically modified silica (ORMOSIL) particles having multiple functional groups.

Here we report a facile one-pot synthetic method for organically modified silica (ORMOSIL) particles having multiple functional groups and demonstrate the homogeneous distribution of functional groups in ORMOSIL particles by chemical reactions of each surface functional group with fluorescent dyes such as fluroescamine and rhodamine B isothiocyanate. Dye-tagged ORMOSIL particles having tri-functional groups are exhibited two fluorescent emission peaks at 475 (blue) and 570 nm (red), indicating the positions of functional groups. The surface reaction of these functionalized ORMOSIL particles with various organic or inorganic materials not only endowed additional functionalities and physical properties, but also produced metallic hybrid composite particles. Chemical and physical properties of functionalized ORMOSIL particles were characterized by FT-IR, solid state (13)C and (29)Si NMR, thermogravimetric analysis (TGA), electron microscopy (SEM and TEM), and X-ray diffraction (XRD) analysis.

Initial in vitro bacterial adhesion on dental restorative materials.

OBJECTIVES: The purpose of this study was to evaluate initial bacterial adhesion on several restorative materials with similar roughness. MATERIALS AND METHODS: Sixty cylindrical slabs were prepared from four restorative materials: zirconia (Zr), alumina-toughened zirconia (Al-Zr), type III gold alloy (Au), and cp-titanium (Ti). All the materials were polished until a mirror-like shine was achieved. The average surface roughness and topography were determined by atomic force microscopy. Contact angles were measured to calculate surface free energy by the sessile drop technique. After the formation of a salivary pellicle, S. sanguinis, S. gordonii, and S. oralis were inoculated onto the specimens and incubated for 4 h. Quantification of the adherent bacteria was performed by crystal violet staining technique and resazurin reduction assay. One-way ANOVA and Tukey's post hoc test were adopted for statistical analysis. The level of significance was 0.05. RESULTS: The Ra values determined with atomic force microscopy for all specimens were lower than 5 nm. Surface free energy increased in the order of Al-Zr, Zr, Ti, and Au. Differences were significant between the investigated materials in both crystal violet absorbance and fluorescence intensities. Gold alloy showed the highest values for all bacterial strains (p<0.05). CONCLUSIONS: Zirconia, alumina-toughened zirconia, and titanium may be more suitable than gold alloy as an abutment material with respect to the initial bacterial adhesion and subsequent advance of peri-implantitis.

Immediate loading on mandibular edentulous patient with SFI Bar® overdenture.

Despite the greater retention and low maintenance of bar attachment system, the longer clinical time and increased number of visits were the assignments to overcome in bar attachment system. This case report describes SFI-Bar® (Cendres et Métaux, Biel/Bienne, Switzerland) to be solve those problems. A 65-year-old female, who had severely absorbed mandible, hoped to wear a stable mandibular denture without pain. As soon as two implants were placed on mandible, a tube bar was connected to two adaptors connected to each implant. The length of the tube bar was adjusted considering inter implant distance, and reconnected to the adaptors. Finally a female part was seated beneath the denture. This case report showed that a satisfactory clinical result was achieved by delivering bar overdenture immediately after implant placement without laboratory procedure.