Minh Khai Le Thieu

• Thieu, Minh Khai Le; Mauland, Erik Klepsland & Verket, Anders (2022). Satisfaction and preferences among patients with both implant-supported single crown and tooth-supported fixed dental prosthesis: a pilot study. Acta Odontologica Scandinavica. ISSN 0001-6357. doi: 10.1080/00016357.2022.2155239. Full text in Research Archive Show summary

  Objective The objective of the study was to assess patient-reported preferences and outcomes in patients rehabilitated with both an implant-supported single crown (ISC) and a tooth-supported fixed dental prosthesis (FDP). Materials and methods The electronic journal system at the Faculty of Dentistry, University of Oslo, was searched to find patients presenting both an ISC and an FDP replacing no more than two teeth between abutments. Identified patients that agreed answered a questionnaire followed by a clinical examination. Descriptive statistics was calculated. Results Thirty patients were included. The mean function time was 11.8 years for FDPs and 6.6 years for ISCs. All but three patients were satisfied with both rehabilitation modalities. No patients were unsatisfied with aesthetics or function of either rehabilitation. All patients reported satisfactory function of their restorations and reported chewing without problems. The self-reported post-operative complications were few, but less than observed in the clinical examinations. Conclusions More patients reported food impaction with their FDP as compared to their ISC. Function and aesthetics of FDPs and ISCs were rated similarly, but more patients found the ISC treatment more uncomfortable. Despite this finding, most patients would prefer to undergo ISC treatment if they were to replace another missing tooth.

• Thieu, Minh Khai Le; Stoetzel, Sabine; Rahmati, Maryam; Khassawna, Thaqif El; Verket, Anders & Sanz-Esporrin, Javier [Show all 9 contributors for this article] (2022). Immunohistochemical comparison of lateral bone augmentation using a synthetic TiO<inf>2</inf> block or a xenogeneic graft in chronic alveolar defects. Clinical Implant Dentistry and Related Research. ISSN 1523-0899. doi: 10.1111/cid.13143. Full text in Research Archive Show summary

  Objectives To evaluate osteogenic markers and alveolar ridge profile changes in guided bone regeneration (GBR) of chronic non-contained bone defects using a non-resorbable TiO2 block. Material and methods Three buccal bone defects were created in each hemimandible of eight beagle dogs and allowed to heal for 8 weeks before GBR. Treatment was assigned by block randomisation: TiO2 block: TiO2-scaffold and a collagen membrane, DBBM particulates: Deproteinised bovine bone mineral (DBBM) and a collagen membrane, Empty control: Only collagen membrane. Bone regeneration was assessed on two different healing timepoints: early (4 weeks) and late healing (12 weeks) using several immunohistochemistry markers including alpha smooth muscle actin (α-SMA), osteopontin, osteocalcin, tartrate-resistant acid phosphatase and collagen type I. Histomorphometry was performed on Movat Pentachrome and Von Kossa/Van Gieson stained sections. Stereolithographic models were used to compare alveolar profile changes. Results The percentage of α-SMA and osteopontin increased in TiO2 group after 12 weeks of healing at the bone-scaffold interface, while collagen type I increased in the empty control group. In the defect area, α-SMA decreased in the empty control group, while collagen type I increased in the DBBM group. All groups maintained alveolar profile from 4 to 12 weeks, but TiO2 group demonstrated the widest soft tissue contour profile. Conclusions The present findings suggested contact osteogenesis when GBR is performed with a TiO2 block or DBBM particulates. The increase in osteopontin indicated a potential for bone formation beyond 12 weeks. The alveolar profile data indicated a sustained lateral increase in lateral bone augmentation using a TiO2 block and a collagen membrane, as compared to DBBM and a collagen membrane or a collagen membrane alone.

• Thieu, Minh Khai Le; Haugen, Håvard Jostein; Esporrin, Javier Sanz; Sanz, Mariano; Lyngstadaas, Ståle Petter & Verket, Anders (2021). Guided bone regeneration of chronic non-contained bone defects using a volume stable porous block TiO2 scaffold: An experimental in vivo study. Clinical Oral Implants Research. ISSN 0905-7161. doi: 10.1111/clr.13708. Full text in Research Archive Show summary

  Objectives To evaluate new lateral bone formation and lateral volume augmentation by guided bone regeneration (GBR) in chronic non‐contained bone defects with the use of a non‐resorbable TiO2‐block. Materials and methods Three buccal bone defects were created in each hemimandible of eight beagle dogs and allowed to heal for eight weeks before treatment by GBR. Each hemimandible was randomly allocated to 4 or 12‐week healing time after GBR and three intervention groups were assigned by block randomization: TiO2 block: TiO2‐scaffold and a collagen membrane, DBBM particles: Deproteinized bovine bone mineral (DBBM) and a collagen membrane, Empty control: Collagen membrane only. Microcomputed tomography (microCT) was used to measure the lateral bone formation and width augmentation. Histological outcomes included descriptive analysis and histomorphometric measurements. Results MicroCT analysis demonstrated increasing new bone formation from four to twelve weeks of healing. The greatest width of mineralized bone was seen in the empty controls, and the largest lateral volume augmentation was observed in the TiO2 block sites. The DBBM particles demonstrated more mineralized bone in the grafted area than the TiO2 blocks, but small amounts and less than the empty control sites. Conclusion The TiO2 blocks rendered the largest lateral volume augmentation but also less new bone formation compared to the DBBM particles. The most new lateral bone formation outward from the bone defect margins was observed in the empty controls, indicating that the presence of either graft material leads to slow appositional bone growth.

• Thieu, Minh Khai Le; Homayouni, Amin; Hæren, Lena Ringsby; Tiainen, Hanna; Verket, Anders & Ellingsen, Jan Eirik [Show all 13 contributors for this article] (2021). Impact of simultaneous placement of implant and block bone graft substitute: an in vivo peri-implant defect model. Biomaterials Research. ISSN 1226-4601. 25(43). doi: 10.1186/s40824-021-00245-3. Full text in Research Archive Show summary

  Background Insufficient bone volume around an implant is a common obstacle when dental implant treatment is considered. Limited vertical or horizontal bone dimensions may lead to exposed implant threads following placement or a gap between the bone and implant. This is often addressed by bone augmentation procedures prior to or at the time of implant placement. This study evaluated bone healing when a synthetic TiO2 block scaffold was placed in circumferential peri-implant defects with buccal fenestrations. Methods The mandibular premolars were extracted and the alveolar bone left to heal for 4 weeks prior to implant placement in six minipigs. Two cylindrical defects were created in each hemi-mandible and were subsequent to implant placement allocated to treatment with either TiO2 scaffold or sham in a split mouth design. After 12 weeks of healing time, the samples were harvested. Microcomputed tomography (MicroCT) was used to investigate defect fill and integrity of the block scaffold. Distances from implant to bone in vertical and horizontal directions, percentage of bone to implant contact and defect fill were analysed by histology. Results MicroCT analysis demonstrated no differences between the groups for defect fill. Three of twelve scaffolds were partly fractured. At the buccal sites, histomorphometric analysis demonstrated higher bone fraction, higher percentage bone to implant contact and shorter distance from implant top to bone 0.5 mm lateral to implant surface in sham group as compared to the TiO2 group. Conclusions This study demonstrated less bone formation with the use of TiO2 scaffold block in combination with implant placement in cylindrical defects with buccal bone fenestrations, as compared to sham sites.

• Haugen, Håvard Jostein; Marovic, Danijela; Par, Matej; Thieu, Minh Khai Le; Reseland, Janne Elin & Johnsen, Gaute Floer (2020). Bulk Fill Composites Have Similar Performance to Conventional Dental Composites. International Journal of Molecular Sciences. ISSN 1661-6596. 21(15), p. 5136–5136. doi: 10.3390/ijms21145136. Full text in Research Archive Show summary

  The aim of the study was to perform comprehensive characterization of two commonly used bulk fill composite materials (SDR Flow (SDR) and Filtek™ Bulk Fill Flowable Restorative (FBF) and one conventional composite material (Tetric EvoCeram; TEC). Eleven parameters were examined: flexural strength (FS), flexural modulus (FM), degree of conversion, depth of cure, polymerisation shrinkage (PS), filler particle morphology, filler mass fraction, Vickers hardness, surface roughness following simulated toothbrush abrasion, monomer elution, and cytotoxic reaction of human gingival fibroblasts, osteoblasts, and cancer cells. The degree of conversion and depth of cure were the highest for SDR, followed by FBF and TEC, but there was no difference in PS between them. FS was higher for bulk fill materials, while their FM and hardness were lower than those of TEC. Surface roughness decreased in the order TEC→SDR→FBF. Bisphenol A-glycidyl methacrylate (BisGMA) and urethane dimethacrylate were found in TEC and FBF eluates, while SDR released BisGMA and triethylene glycol dimethacrylate. Conditioned media accumulated for 24h from FBF and TEC were cytotoxic to primary human osteoblasts. Compared to the conventional composite, the tested bulk fill materials performed equally or better in most of the tests, except for their hardness, elastic modulus, and biocompatibility with osteoblasts.

• Hussain, Badra; Thieu, Minh Khai Le; Johnsen, Gaute Floer; Reseland, Janne Elin & Haugen, Håvard Jostein (2017). Can CAD/CAM resin blocks be considered as substitute for conventional resins? Dental Materials. ISSN 0109-5641. 33(12), p. 1362–1370. doi: 10.1016/j.dental.2017.09.003. Full text in Research Archive Show summary

  Objective Dentists are facing a myriad of new CAD/CAM product for dental filling therapies. Are the new materials any worthwhile using? Are they succeeding the standard filling materials? Here we compare for the first time the new resin-composite blocks (RCBs) with conventional materials (Filtek Z250 and Tetric EvoCeram). Methods The material were tested for residual monomer elution by HPLC, thermogravimetric analysis (TG) was used to determine the percentage of fillers by weight, hardness was evaluated by Vickers method, morphology of fillers and distribution in the matrix were examined by scanning electron microscopy (SEM), elemental analysis for elemental determination of the filler particles was performed by energy-dispersive X-ray spectroscopy (EDX) cytotoxicity using human gingival fibroblasts and an epithelial cell line. Results The RBC outperformed conventional composite regarding mechanical characteristics (hardness) and monomer eluation, but showed some worrisome results regarding cytotoxicity. Significance The cost benefit is not in favour of RBCs in comparison to conventional composites, as the cytotoxicity was found higher for RBCs.

• Johnsen, Gaute Floer; Thieu, Minh Khai Le; Hussain, Badra; Pamula, Elzbieta; Reseland, Janne Elin & Lyngstadaas, Ståle Petter [Show all 7 contributors for this article] (2017). Own brand label restorative materials - A false bargain? Journal of Dentistry. ISSN 0300-5712. 56, p. 84–98. doi: 10.1016/j.jdent.2016.11.004. Full text in Research Archive Show summary

  Objectives This study aims at evaluating and comparing mechanical, chemical, and cytotoxicological parameters of a commercial brand name composite material against two ‘own brand label' (OBL) composites. Methods Parameters included depth of cure, flexural strength, degree of conversion, polymerization shrinkage, filler particle morphology and elemental analyses, Vickers hardness, surface roughness parameters after abrasion, monomer elution, and cytotoxicity. Results The conventional composite outperformed the OBLS in terms of depth of cure (p < 0.001), degree of cure at the first and last time intervals (p < 0.001), hardness (p < 0.001), and post-abrasion roughness (p < 0.05). The polymerization volumetric shrinkage ranged from 2.86% to 4.13%, with the highest shrinkage seen among the OBLs. Both Monomer elution from the OBLs was statistically significantly higher (p<0.001). Statistically significantly higher cytotoxicity combined with altered morphology and loss of confluence was detected in the cells exposed to extracts from the OBLs. Conclusions The OBLs were in general outdone by the conventional composite. Clinical Significance: OBLs restorative materials have become pervasive in the dental market. Manufacturers often promise equal or better characteristics than existing brand-name composites, but at a lower price. Dentists are highly recommended to reconsider utilization of OBLs lacking sound scientific scrutiny, and our findings underscore this recommendation

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• Haugen, Håvard Jostein; Thieu, Minh Khai Le; Sanz-Esporrin, Javier; Alonso, Mariano Sanz & Verket, Anders (2021). GUIDED BONE REGENERATION OF CHRONIC NON-CONTAINED BONE DEFECTS USING A VOLUME STABLE POROUS TIO2 SCAFFOLD: AN EXPERIMENTAL IN VIVO STUDY. Full text in Research Archive
• Haugen, Håvard Jostein; Johnsen, Gaute Floer; Reseland, Janne Elin; Hussain, Badra & Thieu, Minh Khai Le (2017). Can CAD/CAM Resin Blocks be Considered as a Substitute to Conventional Resins? Full text in Research Archive

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