The International Journal of Prosthodontics, Pre-Print
DOI: 10.11607/ijp.7891, PubMed ID (PMID): 36484659December 6, 2022,Pages 1-17, Language: EnglishDerksen, Wiebe / Wismeijer, DanielPurpose: To report on the follow-up of two earlier published RCTs on the performance of screw-retained monolithic zirconia restorations on Ti-base abutments based on intraoral optical scanning or conventional impressions.
Materials and Methods: A total of 54 patients receiving 89 restorations (44 single crowns [SC]), 21 splinted crowns [2-FDP], and 24 three-unit fixed partial dentures (3-FDP)] were included in the 1- to 3-year follow-up period. The restoration survival and technical complications were documented.
Results: A total of 50 patients with 84 restorations completed the 3-year follow-up. One 3-FDP from the IOS group was lost. This resulted in survival rates of 97.9% for the test and 100% for the control restorations and an overall survival rate of screw-retained monolithic zirconia restorations on implants of 98.8% after 3 years. There was no statistically significant survival difference between the test and control groups (P = .362). When evaluated separately, a 100% survival rate for SCs and 97.7% rate for 2-FDPs was reported. One decementation and three occurrences of screw loosening occurred over the 1- to 3-year follow-up. The multiple-implant restorations showed higher (23.3%) complication rates at the restoration level than the SCs (4.9%) after 3 years of function (P = .026).
Conclusion: Screw-retained monolithic zirconia restorations on Ti-base abutments show promising survival rates after 3 years of function. Restorative complications of screw-retained monolithic zirconia restorations on Ti-base abutments are more likely to happen in the first year of function and are more common in multiple-implant restorations than solitary crowns. The impression (IOS or conventional) does not seem to influence these results.
The International Journal of Prosthodontics, 4/2023
DOI: 10.11607/ijp.7891, PubMed ID (PMID): 37699181Pages 410-415, Language: EnglishDerksen, Wiebe / Wismeijer, DanielPurpose: To report on the follow-up of two previously published RCTs on the performance of screw-retained monolithic zirconia restorations on titanium (ti)-base abutments based on either digital scans through intraoral optical scanning (IOS) or conventional impressions. Materials and Methods: A total of 54 patients receiving 89 restorations (44 solitary crowns [SC], 21 splinted crowns [2-FDP], and 24 three-unit fixed partial dentures [3-FDP]) were included for the 1- to 3-year follow-up period. Restoration survival and technical complications were documented. Results: In total, 50 patients with 84 restorations completed the 3-year follow-up. One 3-FDP from the digital group was lost. This resulted in a survival rate of 97.9% for the digital group and 100% for the conventional group and an overall survival rate of 98.8% for screw-retained monolithic zirconia restorations on implants after 3 years. There was no statistically significant survival difference between the digital and conventional restorations (P = .362). When evaluated separately, a 100% survival rate of SCs and 97.7% for 2-FDPs could be reported. One decementation and three screw loosenings occurred in the 1- to 3-year follow-up. The multiple-implant restorations showed higher (23.3%) complication rates at the restoration level than the SCs (4.9%) after 3 years of function (P = .026). Conclusions: Screw-retained monolithic zirconia restorations on ti-base abutments show promising survival rates after 3 years of function. Restorative complications in screw-retained monolithic zirconia restorations on Ti-base abutments are more likely to happen in the first year of function and are more common in multiple-implant restorations than SCs. The impression type (digital or conventional) does not seem to influence these results.
International Journal of Periodontics & Restorative Dentistry, 1/2023
Online OnlyDOI: 10.11607/prd.5711, PubMed ID (PMID): 36661881Pages e35-e42, Language: EnglishTabassum, Afsheen / Wismeijer, Daniel / Hogervorst, J M A / Siddiqui, Intisar Ahmad / Kazmi, Farhat / Tahmaseb, AliAutogenous particulate bone grafts are being utilized in oral implantology for minor grafting procedures. This study aimed to investigate the influence of the bone-harvesting technique, donor age, and donor site on proliferation and differentiation of human primary osteoblast-like cells in the cell culture. Autogenous bone particles (20 samples) were harvested from the maxilla and mandible during surgery using two different protocols, and two types of particulate bone grafts were collected: bone chips and bone sludge. Bone samples were cultured in growth medium and, after 2 to 3 weeks, the cells that grew from bone grafts were cultured in the normal and osteogenic medium for 0, 4, 7, and 20 days. DNA, alkaline-phosphatase (ALP), calcium-content measurements, and Alizarin red/toluidine blue staining were performed. Data were analyzed by repeated-measures analysis of variance with Bonferroni test. The level of statistical significance was set at 5% (P < .05). Total DNA, ALP, and calcium content were significantly higher for the bone chip samples compared to the bone sludge samples. Total DNA and ALP content were significantly higher for the patients in age group 1 (≤ 60 years) compared to age group 2 (> 60 years) and was significantly higher for mandibular samples than maxillary samples on day 20. However, the calcium measurement showed no significant difference concerning donor age and donor site. Data analysis revealed that harvesting technique (bone chips vs bone sludge), donor age (≤ 60 years vs > 60 years), and donor site (maxilla vs mandible) influenced the osteogenic potential of the collected particulate bone graft. The bone chips were superior in terms of osteogenic efficacy and should be considered a suitable option for particulate bone graft collection.
The International Journal of Prosthodontics, 6/2021
DOI: 10.11607/ijp.7074Pages 733-743, Language: EnglishDerksen, Wiebe / Tahmaseb, Ali / Wismeijer, Daniel
Purpose: To compare the fit and clinical performance of screw-retained monolithic zirconia implant fixed dental prostheses (FDPs) based on either intraoral optical scanning (IOS) or conventional impressions.
Materials and methods: Patients with two posterior tissue-level implants (Straumann Regular Neck) replacing two or three adjacent teeth were recruited. Impressions were taken with both IOS (True Definition Scanner, 3M ESPE) and a conventional (polyether) pick-up impression. Double-blind randomization was performed after impression-taking, and patients were to receive an FDP based on either the digital or the conventional impression. The fit was evaluated, and the time required for adjustments was recorded. Additionally, survival and technical complication rates with a follow-up of 1 year were documented.
Results: A total of 38 patients requiring 45 FDPs were included: 24 FDPs in the test (IOS) and 21 in the control (conventional) group. The average adjustment time was 6.92 minutes (SD: ± 10.84, range: 0 to 49 minutes) for digital vs 12.38 minutes (SD: ± 14.52, range: 0 to 54 minutes) for conventional impressions (P = .090). A proper fit (no adjustments) was achieved in 33.3% of the digital and 28.6% of the conventional group. Forty-two FDPs could be placed within the two planned appointments, and 3 FDPs exhibited an unacceptable fit and required an extra appointment. Eight technical complications occurred during the first year of function. The overall restoration survival rate was 100%.
Conclusion: The clinical fit of CAD/CAM FDPs based on digital impressions is comparable to conventional impressions. Screw-retained monolithic zirconia FDPs on Ti-base abutments show low major complication and survival rates in the short term.
The International Journal of Oral & Maxillofacial Implants, 6/2021
Online OnlyDOI: 10.11607/jomi.9029Pages e175-e182, Language: EnglishTabassum, Afsheen / Kazmi, Farhat / Wismeijer, Daniel / Siddiqui, Intisar Ahmad / Tahmaseb, Ali
Purpose: There is a substantial need to perform studies to evaluate crestal bone loss (CBL) and implant success when using a newly introduced low-speed drilling protocol. Therefore, this study aimed to evaluate the mean CBL and implant success rate by placing implants utilizing two drilling protocols, ie, standard and low-speed drilling protocols.
Materials and methods: A randomized controlled clinical trial was carried out in patients who required dental implants to restore their esthetics and function. The patients were recruited from a university hospital (Academic Centre for Dentistry Amsterdam [ACTA], the Netherlands). Based on the inclusion criteria, patients were randomized to two study groups: (1) control group, standard drilling protocol; and (2) test group, low-speed drilling protocol without saline irrigation. The mean CBL and the implant success rate were evaluated after 12 months of implant placement.
Results: Twenty-three patients (15 men and 8 women with a mean age of 57.5 ± 10.7 years) contributed to the study. Forty Camlog screw-line implants were placed (20 implants per study group). After 12 months of implant placement, the mean CBL of implants placed with the standard protocol and the low-speed protocol was 0.206 ± 0.251 mm and 0.196 ± 0.178 mm, respectively. No statistically significant difference could be recorded among both groups (P = .885). Concerning implants placed in the maxilla, the standard drilling group and low-speed drilling group showed a mean CBL of 0.252 ± 0.175 mm and 0.251 ± 0.175 mm, respectively, compared with 0.173 ± 0.210 mm and 0.141 ± 0.172 mm in the mandible, with no significant difference. The success rate of dental implants at 12 months was 95% in the control group and 90% in the test group.
Conclusion: Within the limitations of this study, it can be concluded that implants placed with the low-speed drilling protocol without saline irrigation exhibited a similar CBL compared with implants placed with the standard drilling protocol. However, a higher success rate was recorded especially in type 1-quality bone for the control group compared with the test group. Further randomized clinical trials with greater sample sizes and extended follow-up times should be performed to obtain stronger evidence and a better understanding of the influence of drilling speed on mean CBL and long-term implant success.
Keywords: crestal bone loss, dental implant, low-speed drilling, standard drilling
The International Journal of Oral & Maxillofacial Implants, 1/2020
DOI: 10.11607/jomi.7648, PubMed ID (PMID): 31184630Pages 141-149, Language: EnglishTabassum, Afsheen / Wismeijer, Daniel / Hogervorst, J.M.A. / Tahmaseb, AliPurpose: Autogenous bone grafts are considered a "gold standard." The success of autografts mainly depends on their ability to promote an osteogenic response. The aim of this study was to collect autogenous bone during implant osteotomy preparation using two different drilling protocols and to evaluate and compare the proliferation and differentiation ability of the collected bone particles.
Materials and Methods: Autogenous bone particles were harvested from 20 patients during implant osteotomy preparation using two different drilling protocols: (1) standard drilling protocol with saline irrigation (according to the manufacturer's recommendation) and (2) low-speed drilling protocol without saline irrigation (speed 200 rpm). Collected bone samples were cultured in growth medium, and after 2 to 3 weeks, cells that grew out from bone grafts were cultured in the normal medium as well as in osteogenic medium for days 0, 4, 7, and 20. Scanning electron microscopy, alizarin red/toluidine blue staining, DNA, ALP, and calcium content measurements were performed. Repeated measures analysis of variance (ANOVA) with Bonferroni's test was employed to analyze the data of this study.
Results: The total DNA content was significantly higher for the low-speed drilling samples compared with the standard drilling on day 4 (P .05), day 7 (P .01), and day 20 (P .001) in the normal medium and on day 7 (P .01) and day 20 (P .01) in the osteogenic medium. Besides, calcium measurements and mineralized matrix formation observed with alizarin red/toluidine blue staining were significantly higher for the low-speed drilling group compared with the standard drilling group.
Conclusion: Osteogenic efficacy (differentiation and proliferation) of autogenous bone particles collected using low-speed drilling was superior compared with standard drilling samples.
Keywords: bone graft(s), bone remodeling/regeneration, cell differentiation, dental implants, mineralized tissue/development, osteoblast
International Journal of Periodontics & Restorative Dentistry, 3/2019
DOI: 10.11607/prd.3980, PubMed ID (PMID): 30986287Pages 371-379, Language: EnglishTeng, Fei / Zheng, Yuanna / Wu, Gang / Beekmans, Bart / Wismeijer, Daniel / Lin, Xingnan / Liu, YuelianThis study aimed to histologically investigate the bone tissue response to zirconia implants functionalized with a biomimetic calcium phosphate (CaP) coating incorporated with bone morphogenetic protein-2 (BMP-2). Zirconia implants coated with biomimetic CaP were prepared with and without BMP-2. Untreated zirconia implants served as a control. These three groups of implants were placed randomly in the mandibles of six beagle dogs (n = 6). Three months later, samples were harvested for histomorphometric analysis. The present study showed that the application of a biomimetic CaP coating incorporated with BMP-2 enhanced the peri-implant osteogenesis for zirconia implants.
The International Journal of Oral & Maxillofacial Implants, 2/2019
DOI: 10.11607/jomi.6980, PubMed ID (PMID): 30883624Pages 481-488, Language: EnglishZembic, Anja / Tahmaseb, Ali / Jung, Ronald E. / Wiedemeier, Daniel / Wismeijer, DanielPurpose: This cohort study evaluated patient satisfaction for maxillary implant-retained overdentures (IODs) on two implants up to 4 years and assessed the treatment effect over time.
Materials and Methods: Patients encountering problems with their conventional dentures were included and received maxillary IODs on two titanium-zirconium implants and ball anchors in the canine area. Patient satisfaction was assessed using the oral health impact profile (OHIP-20E) questionnaires both for dentures and IODs. Two months after insertion of IODs (baseline), the patients chose the preferred overdenture design with full or reduced palatal coverage. OHIP-20E questionnaires were followed according to the individual choice at 1 and 4 years, and outcomes were compared with baseline.
Results: Sixteen out of 21 patients were evaluated at a mean follow-up of 4 years (range: 2.4 to 4.8 years). There was no significant difference in the OHIP domains for IODs at 1 year (OHIP_total_1y: 9.5, SD: 13.0) and 4 years (OHIP_total_4y: 14.2, SD: 19.1) compared with baseline (OHIP_total_BL: 12.4, SD: 14.7). Patients were most satisfied with social disability both for IODs (OHIP_BL: 6.0, SD: 7.6; OHIP_1y: 3.4, SD: 5.4; OHIP_4y: 5.7, SD: 9.5) and dentures (OHIP_CD_old: 28, SD: 29.7; OHIP_CD_new: 25.4, SD: 28.67). Patients were least satisfied with functional limitation both for IODs (OHIP_BL: 6.0, SD: 7.6; OHIP_1y: 3.4, SD: 5.4; OHIP_4y: 5.7, SD: 9.5) and dentures (OHIP_CD_old: 28, SD: 29.7; OHIP_CD_new: 25.4, SD: 28.67).
Conclusion: Patient satisfaction with maxillary IODs on two implants did not change from baseline to 4 years and was high at 4 years of function.
Keywords: dental implants, dental prosthesis, edentulous, implant-supported, jaw, maxilla, overdenture, patient-reported outcomes, patient satisfaction, quality of life
2019-2
Pages 110-117, Language: EnglishTahmaseb, Ali / te Poel, Jobine / Wismeijer, DanielComputer Aided Implant Surgery (CAIS) has lately been gaining popularity among dental clinicians. Several software packages and associated tools are available on the market. Recent literature reviews show that inaccuracies often occur when these techniques are applied. In this article, the authors give an overview of the tools available for CAIS along with their benefits and shortcomings as well as possible solutions to improve overall accuracy in CAIS.
Keywords: Guided surgery, computer planning, CAIS
QZ - Quintessenz Zahntechnik, 2/2018
SciencePages 170-186, Language: GermanAlharbi, Nawal / Wismeijer, Daniel / Osman, Reham B.Eine kritische Standortbestimmung der LiteraturIn der Prothetik werden verschiedene additive Fertigungsverfahren zur Herstellung von Gerüsten festsitzender Restaurationen, Metallgerüsten herausnehmbarer Teilprothesen sowie von Kunststoff-Mock-ups und Kunststoffmodellationen für den klassischen Metallguss eingesetzt. Die additive Fertigung erweist sich hier als vielversprechend, auch wenn ihre Anwendung noch Einschränkungen unterliegt. Eine Beschäftigung mit diesen Grenzen und aktuellen Entwicklungen der Werkstoffkunde ist unerlässlich, bevor die additive Fertigung als akzeptables Herstellungsverfahren für Zahnersatz gelten darf.
Keywords: Additive Fertigungsverfahren, 3-D-Druck, Prothetik, Gerüstherstellung, Review
