Jen-Chyan Wang

Properties of osteoconductive biomaterials: Calcium phosphate cement with different ratios of platelet-rich plasma as identifiers

This study aims to evaluate further the performance of a platelet-rich plasma (PRP) additive incorporated with calcium phosphate bone cement (CPC) in vitro to prove its efficiency as bone graft substitutes and its compatibility to be incorporated into the CPC with other techniques in clinical restoration in vivo. The growth factor release ability and the osteogenic evaluation of PRP, CPC, and PRP/CPC testing groups with 5, 10, and 15 wt.% PRP were compared in vitro. Four groups were measured using non-decalcified staining methods in vivo, which include the testing group of 10 wt.% PRP/CPC selected from the evaluation in vitro, by using both the autograft with rabbit trabecular and CPC-only as comparison groups and the group without grafting material as the control sample. The results obtained through specimen immersion show that growth factor release and alkaline phosphatase activities after osteoprogenitor cell culture had a significantly better effect on 10 and 15 wt.% PRP/CPC than on the other groups in vitro. Analysis results suggest that PRP was still retained in the CPC matrix even after 32 days of immersion. The results in vivo show that the histology of the autograft bone and the control group without grafting material exhibited fibrous connective and adipose tissues, which obviously filled the created cavity even at nine weeks after the operation. Osteoregeneration was more successful in the PRP-additive group, which accumulated bone remodeling than in the other groups. In conclusion, CPC could be a potential carrier with adequate PRP additives that bear a therapeutic potential for enhanced bone tissue regeneration.

Deriving fast setting properties of tetracalcium phosphate/ dicalcium phosphate anhydrous bone cement with nanocrystallites on the reactant surfaces

OBJECTIVE This study attempts to reveal how nanocrystallites on the ceramic surfaces of non-dispersive calcium phosphate cement (nd-CPC) participate in setting processes as compared with conventional CPC (c-CPC). METHODS The compositions and morphologies of CPC during the early setting reactions were studied with X-ray diffraction and a scanning transmission electron microscope equipped with an energy dispersive spectroscopy system. The pH values and dispersive properties of CPC during the early setting reactions were investigated as well as the compressive strength of nd-CPC after 24h of immersion with varying liquid to powder ratios. RESULTS The mechanical strength of nd-CPC was approximately 60MPa after a 24h immersion in simulate body solution with a P/L ratio between 3.3 and 4.2g/mL. The nanocrystallites on the particle surfaces of nd-CPC were shown to grow rapidly and provided interlocking sites that allowed rapid development of the apatite phase in the cement, and were also shown to be non-dispersive in solution as determined by an injection test of c-CPC. CONCLUSIONS The interlocking particles produced by whisker growth on the ceramic particles or new crystallites formed between the ceramic particles caused the cement to be non-dispersive in solution. The particles of reactants with nanocrystallites on surfaces also gave this cement the ability to be shaped easily as a paste during an operation or to be injected into a cavity.

Impacted mandibular second molars.

OBJECTIVE To determine the prevalence and severity of impacted permanent mandibular second molars (MdM2s) in the general population of Taiwan as well as to evaluate treatment outcomes with an innovative method for impacted MdM2s. MATERIALS AND METHODS Dental records of 21,580 patients were retrospectively screened in this study. The impactions of MdM2s were registered. The chosen study population consisted of 96 patients with 125 impacted MdM2s who received orthodontic treatment in our clinics. Standardized periapical radiographs were taken to measure the angles and depths of the impacted MdM2s. In addition, the initial uprighting periods of the impacted MdM2s were recorded. RESULTS The prevalence of MdM2 impaction in the Taiwanese population was 0.65%. Most of the angles and depths of the MdM2s were 31-60° and 9-12 mm, respectively. The mean initial uprighting period of the impacted MdM2 was 3.6 months. There were no significant differences between genders in the initial uprighting period based on patient ages, impacted angles, or impacted depths (P > .05). Correlation analysis revealed that the impacted depth was highly and positively correlated with the initial uprighting period (r > .75). CONCLUSIONS The prevalence of MdM2 impaction in this study was low but slightly higher than previous reports investigating whites. Although such impactions are rare, it is recommended to diagnose early for an optimal treatment time and reduction of complications. In addition, the effective molar uprighting appliance used in this study has displayed good treatment outcomes with natural improvement of the adjacent infrabony defects of the first molars.

Osteoregenerative capacities of dicalcium phosphate-rich calcium phosphate bone cement.

Calcium phosphate cement (CPC) is a widely used bone substitute. However, CPC application is limited by poor bioresorption, which is attributed to apatite, the stable product. This study aims to systematically survey the biological performance of dicalcium phosphate (DCP)-rich CPC. DCP-rich CPC exhibited a twofold, surface-modified DCP anhydrous (DCPA)-to-tetracalcium phosphate (TTCP) molar ratio, whereas conventional CPC (c-CPC) showed a onefold, surface unmodified DCPA-to-TTCP molar ratio. Cell adhesion, morphology, viability, and alkaline phosphatase (ALP) activity in the two CPCs were examined with bone cell progenitor D1 cultured in vitro. Microcomputed tomography and histological observation were conducted after CPC implantation in vivo to analyze the residual implant ratio and new bone formation rate. D1 cells cultured on DCP-rich CPC surfaces exhibited higher cell viability, ALP activity, and ALP quantity than c-CPC. Histological evaluation indicated that DCP-rich CPC showed lesser residual implant and higher new bone formation rate than c-CPC. Therefore, DCP-rich CPC can improve bioresorption. The newly developed DCP-rich CPC exhibited potential therapeutic applications for bone reconstruction.

Evaluation of Stress Induced by Implant Type, Number of Splinted Teeth, and Variations in Periodontal Support in Tooth-Implant-Supported Fixed Partial Dentures: A Non-Linear Finite Element Analysis

BACKGROUND This study investigated the biomechanical interactions in tooth-implant-supported fixed partial dentures (FPDs) with variations in periodontal support, implant system, number of splinted teeth, and load type using the non-linear finite element (FE) approach. METHODS The section contours of the alveolar bone, abutment teeth, and prosthesis were acquired using computed tomography (CT) and micro-CT to construct the FE models with normal periodontal support (NPS) and compromised periodontal support (CPS) containing one- and two-piece implants splinted to the first and second premolars. Realistic interface conditions within the implant system were simulated using frictional contact elements. The main effects for each level of investigated factors in terms of stress values and dissimilar mobility of natural teeth and the implant were computed for all models. RESULTS Analytic results indicated that the load condition was the predominant factor affecting stress developed in the implant, bone, and prosthesis. Additionally, the oblique occlusal forces increased the stress values relative to that of axial analogs. A splinted system with a two-piece implant increased stress on the bone and decreased stress on the prosthesis compared to that of the one-piece implant. The splinted system with a CPS only slightly increased implant stress on the bone compared to that of the splint system with NPS. Splinting an additional tooth did not significantly impact stress values for the tooth-implant-supported FPD. CONCLUSIONS A one-piece structure implant may be better than that of a two-piece structure implant in decreasing bone stress when a natural tooth is planned to connect with an implant. The factors of periodontal support and number of splinted teeth only slightly influenced stress in tooth-implant-supported FPDs.

Biphasic products of dicalcium phosphate-rich cement with injectability and nondispersibility

In this study, a calcium phosphate cement was developed using tetracalcium phosphate and surface-modified dicalcium phosphate anhydrous (DCPA). This developed injectable bone graft substitute can be molded to the shape of the bone cavity and set in situ through the piping system that has an adequate mechanical strength, non-dispersibility, and biocompatibility. The materials were based on the modified DCPA compositions of calcium phosphate cement (CPC), where the phase ratio of the surface-modified DCPA is higher than that of the conventional CPC for forming dicalcium phosphate (DCP)-rich cement. The composition and morphology of several calcium phosphate cement specimens during setting were analyzed via X-ray diffractometry and transmission electron microscopy coupled with an energy dispersive spectroscopy system. The compressive strength of DCP-rich CPCs was greater than 30MPa after 24h of immersion in vitro. The reaction of the CPCs produced steady final biphasic products of DCPs with apatite. The composites of calcium phosphate cements derived from tetracalcium phosphate mixed with surface-modified DCPA exhibited excellent mechanical properties, injectability, and interlocking forces between particles, and they also featured nondispersive behavior when immersed in a physiological solution.

Management of unilaterally deep impacted first, second, and third mandibular molars

Simultaneous impactions of first, second, and third permanent molars comprises a very rare clinical situation with diverse therapeutic approaches and is a difficult challenge for dentists. Early diagnosis and treatment of eruption disturbances contributes to optimal outcomes. This article reports the treatment of a teenager with severe impaction of right mandibular first, second, and third molars, which hinders the masticatory function and dental arch integrity. A decision-making process and a simple orthodontic technique are described. To shorten the treatment time and simplify the procedures, the impacted right mandibular third and second molars were orthodontically uprighted with an innovative tip-back cantilever. Subsequently, the deeply impacted right mandibular first molar was extracted with minimal obstacles. The combined surgical-orthodontic approach resolved a challenging clinical problem and eliminated the need for prosthetic or dental implant replacement of the impacted molars. Good occlusion, normal function, and a healthy periodontium of the patient were also achieved.

Fracture load of provisional fixed partial dentures with long-span fiber-reinforced acrylic resin and thermocycling

Background/purpose The purpose of this study was to evaluate the fracture load and fracture pattern of fiber-reinforced long-span acrylic resin provisional fixed partial dentures (FPDs) with different fiber types and reinforcement lengths after thermocycling. Materials and methods Eighty standardized four-unit FPDs of polymethyl methacry-late resin were fabricated on a metal jig and evenly divided into eight groups. The control and comparison groups were unreinforced acrylic specimens and specimens reinforced with 4-mm steel wire, respectively. The six experimental groups comprised acrylic FPDs reinforced with 4-, 18-, and 30-mm glass fiber (FibreKor) or polyethylene fiber (Construct). Results One-way ANOVA results revealed statistically significant differences between the fracture loads of the experimental and control/comparison groups (P Conclusion The results of this study indicate that fiber reinforcement with FibreKor/Construct enhanced the fracture load of long-span acrylic resin provisional FPDs after thermocycling.

Three-dimensional relationship of the maxillary anterior teeth to the incisive papilla in young adults.

The use of the incisive papilla as an important guide for setting maxillary teeth has been applied in prosthetic dentistry. The purpose of this study was to estimate the relationship between maxillary anterior teeth and the incisive papilla of young adults with approximately optimal occlusion in Taiwan. Study casts of 100 young adults (50 males, 50 females; mean age, 22.4 years) were selected in this study. All of the marked points on maxillary casts were measured using a three‐dimensional precise measuring device. The relative positions of maxillary teeth landmarks to incisive papilla were measured and analyzed using SAS software (JMP 4.02). Students t test and Pearsons correlation test were used to test the statistical significance of any differences (p < 0.05). The results showed that the mesiolabial incisal edge of the upper central incisor was 7.30 ± 0.64mm anterior to the center of the incisive papilla. There was no significant difference in gender (p > 0.05). The intercanine line was 0.27 ± 1.30 mm posterior to the center of incisive papilla. There was no significant difference in gender (p > 0.05). The horizontal distances of the mesiolabial incisal edge of the upper central incisor and the intercanine line to the center of the incisive papilla showed only weak correlation (r < 0.5). In addition, the three‐dimensional relationship of maxillary anterior teeth to the center of the incisive papilla was measured and analyzed. We suggest using the incisive papilla as a reference landmark for the setting of maxillary anterior teeth.

Augmented reality (AR) and virtual reality (VR) applied in dentistry

The OSCE is a reliable evaluation method to estimate the preclinical examination of dental students. The most ideal assessment for OSCE is used the augmented reality simulator to evaluate. This literature review investigated a recently developed in virtual reality (VR) and augmented reality (AR) starting of the dental history to the progress of the dental skill. As result of the lacking of technology, it needs to depend on other device increasing the success rate and decreasing the risk of the surgery. The development of tracking unit changed the surgical and educational way. Clinical surgery is based on mature education. VR and AR simultaneously affected the skill of the training lesson and navigation system. Widely, the VR and AR not only applied in the dental training lesson and surgery, but also improved all field in our life.