New clinical application of digital intraoral scanning technology in occlusal reconstruction: A case report.

BACKGROUND: Digital intraoral scanning, although developing rapidly, is rarely used in occlusal reconstruction. To compensate for the technical drawbacks of current occlusal reconstruction techniques, such as time consumption and high technical requirements, digital intraoral scanning can be used in clinics. This report aims to provide a way of selecting the most suitable maxillo-mandibular relationship (MMR) during recovery. CASE SUMMARY: A 68-year-old man with severely worn posterior teeth underwent occlusal reconstruction with fixed prosthesis using digital intraoral scanning. A series of digital models in different stages of treatment were obtained, subsequently compared, and selected using digital intraoral scanning together with traditional measurements, such as cone beam computed tomography, joint imaging, and clinical examination. Using digital intraoral scanning, the MMR in different stages of treatment was accurately recorded, which provided feasibility for deciding the best occlusal reconstruction treatment, made the treatment process easier, and improved patient satisfaction. CONCLUSION: This case report highlights the clarity, recordability, repeatability, and selectivity of digital intraoral scanning to replicate and transfer the MMR during occlusal reconstruction, expanding new perspectives for its design, fabrication, and postoperative evaluation.

Correlation between clinical parameters of crown and gingival morphology of anterior teeth and periodontal biotypes.

BACKGROUND: In this study, we conducted a quantitative analysis of the clinical parameters of crown and gingival morphology (CGM) of the maxillary anterior teeth (MAT). We also analyzed the correlation of these parameters with periodontal biotype (PB), with a view to providing objective standards for PB diagnosis. METHODS: The three-dimensional (3D) maxillary digital models of 56 individuals were obtained using an intra-oral scanner. The following parameters were measured with the SpaceClaim software: gingival angle (GA), papilla width (PW), papilla height (PH), crown length (CL), crown width (CW), crown width/crown length ratio (CW/CL), bucco-lingual width of the crown (BLW), contact surface width (CSW), and contact surface height/crown length ratio (CS/CL). The PB were determined based on the transparency of the periodontal probe through the gingival sulcus. Independent factors influencing PB were analyzed by logistic regression, and the optimal cutoff values for the independent influencing factors were analyzed using receiver operating characteristic curves (ROC curves). RESULTS: There was no significant difference in the parameters of CGM of the MAT at the left and right sides. The thick biotype accounted for 69.6%, and the parameters of GA, PW, PH, CW, CW/CL and CS/CL were significantly correlated with PB (P ≤ 0.2). GA (odds ratio (OR) = 1.206) and PW (OR = 5.048) were identified as independent predictive factors of PB, with areas under the ROC curve (AUC) of 0.807 and 0.881, respectively, and optimal cutoff values of 95.95° and 10.01 mm, respectively. CONCLUSION: The CGMs of the MAT at the left and right side are symmetrical. The thin biotype accounts for a small proportion, and GA and PW are independent influencing factors of PB. GA of 95.95° and PW of 10.01 mm are the optimal cutoff values for categorization of individuals as thick biotype. This indicates that when the GA and PW of the right maxillary central incisor are G ≥ 95.95° and ≥ 10.01 mm, respectively, there is a higher probability that these individuals will be categorized as thick biotype.

[Selective laser sintering and performances of porous titanium implants].

OBJECTIVE: This work aims to analyze the mechanical properties and biocompatibility of porous titanium (Ti) implants fabricated by selective laser sintering (SLS) and investigate the promotion of osseointegration by porous titanium implant combined with chitosan (CS)/hydroxyapatite(HA) composite coating. METHODS: Ti6Al4V specimens were prepared, and CS/HA composite coating was fabricated on the surface of a portion of the specimens. The mechanical properties of the samples were observed by scanning electron microscope. MC3T3-E1 cells were cultured in vitro, and their biological properties in vitro were analyzed using live and dead viability cell staining method, methyl thiazolyl tetrazolium (MTT) staining, and alkaline phosphatase (ALP) level detection. The thread implant specimens were implanted in the femoral condyle of rabbits, and biological performance was evaluated in vivo. RESULTS: Quasi-elastic gradient of porous specimens decreased with increasing porosity, and the quasi-elastic gradient were close to cortical and cancellous bone when the porosities were 30% and 70%. The specimens showed good biocompatibility. Combined with CS/HA coating, the implants promoted the proliferation and differentiation of MC3T3-E1 cells and facilitated the entry of bone tissue into pores and good osteogenesis. CONCLUSIONS: The porous titanium implant exhibited favorable mechanical properties and biocompatibility. Combined with CS/HA coating, the implant exhibited bone inducibility, which leads to stable osteogenesis.

A quantitative research on clinical parameters of gingival contour for anterior teeth esthetic analysis and design.

OBJECTIVES: To provide reference for computer-aided esthetic analysis and design of the maxillary anterior teeth. MATERIALS AND METHODS: Intraoral scanner was used to obtain the maxillary three-dimensional digital models of subjects with healthy periodontal tissue. In SpaceClaim, the occlusal plane was established as the horizontal reference plane to measure the positional relation between the gingival zenith (GZ) of the maxillary anterior teeth, the angle formed between the gingival line and the maxillary midline (GLA), the distance between the GZ of the lateral incisor and gingival line (LID), and the distance between the GZ and the vertical bisected middle surface along the long axis of the clinical crown (VBMS). RESULTS: The GLA was 92.7 ± 3.2°. The GZ of the canine, lateral incisor, and left central incisor were located to the GZ of the right central incisor coronally at 0.68 ± 0.91, 0.65 ± 0.66 mm, and apically at 0.12 ± 0.42 mm, respectively. The LID was 0.65 ± 0.92 mm. The GZ of the canine, lateral incisor, and central incisor were located distally to the VBMS at 0.00 ± 0.06, 0.27 ± 0.19, and 0.73 ± 0.21 mm, respectively. CONCLUSION: The GZ at different tooth position are in different heights. The direction and degree of the GZ deviation from the VBMS are also related to tooth position. CLINICAL SIGNIFICANCE: The clinical parameters of the gingival contour obtained in this research can be used for patients with unsound contour of periodontal soft tissue to do the anterior teeth esthetic analysis. Besides, it can also be used to determine the proper position between the GZs of the maxillary anterior teeth in anterior teeth esthetic design.

The Protocol of Fixed Reconstruction for Severely Worn Teeth Combined with Anterior Deep Bite.

Full mouth reconstruction is one of the most effective methods to restore severe worn teeth that have suffered reduced vertical dimension. Although the use of the overlay splint restoration for a trial period allowing the patient to adapt to an increased vertical dimension is the recognized method, the specific protocol from the transitional splint to the fixed reconstruction is yet to be established. This case report describes a 50-year-old female patient who has severely worn teeth combined with an anterior deep bite and chewing pain. The protocol of the treatment process is described.

Influence of inner circular sealing area impression method on the retention of complete dentures.

The aims of the present study were to describe an impression method of "inner circular sealing area" and to evaluate the effect of the method on retention, aesthetics and comfort of complete dentures, which lack labial base for patients with maxillary protrusions. Three patients were subjected to the experiment, and two sets of complete maxillary dentures were made for each patient; the first set was made without labial base via an inner circular sealing area method (experimental group) and the second had an intact base that was made with conventional methods (control group). Retention force tests were implemented with a tensile strength assessment device to assess the retention and a visual analogue scale (VAS) was used to evaluate the comfort between the two groups. Results showed larger retention force, better aesthetics and more comfort in the experimental group. The improved two-step impression method formed an inner circular sealing area that prevented damage to the peripheral border seal effect of the denture caused by incomplete bases and obtained better denture retention.

Influence of Inner Circular Sealing Area Impression Method on the Retention of Complete Dentures

The aims of the present study were to describe an impression method of "inner circular sealing area" and to evaluate the effect of the method on retention, aesthetics and comfort of complete dentures, which lack labial base for patients with maxillary protrusions. Three patients were subjected to the experiment, and two sets of complete maxillary dentures were made for each patient; the first set was made without labial base via an inner circular sealing area method (experimental group) and the second had an intact base that was made with conventional methods (control group). Retention force tests were implemented with a tensile strength assessment device to assess the retention and a visual analogue scale (VAS) was used to evaluate the comfort between the two groups. Results showed larger retention force, better aesthetics and more comfort in the experimental group. The improved two-step impression method formed an inner circular sealing area that prevented damage to the peripheral border seal effect of the denture caused by incomplete bases and obtained better denture retention.

O objetivo deste caso foi descrever um método de impressão por "área de selamento circular interno" e avaliar o efeito deste método na retenção, estética e conforto de próteses totais sem base labial para pacientes com protrusão maxilar. Três pacientes foram objeto desta experiência e foram feitas duas próteses maxilares completas para cada um deles; a primeira foi elaborada sem base labial pelo método de área de selamento circular interno (grupo experimental) e a outra teve uma base feita pelo método convencional (grupo controle). Foram realizados testes de retenção com estudo de tensão para avaliar a retenção e para avaliação do conforto dos dois grupos, foi empregada a escala analógica visual (EAV). Os resultados demonstraram que o grupo experimental apresentou força de retenção maior, estética melhor e mais conforto. O método modificado de impressão em duas etapas formou uma área de selamento circular interno que evitou danos ao selamento periférico causados por bases incompletas e obteve melhor retenção da prótese.

Differentially expressed genes and signalling pathways are involved in mouse osteoblast-like MC3T3-E1 cells exposed to 17-ß estradiol.

Oestrogen is essential for maintaining bone mass, and it has been demonstrated to induce osteoblast proliferation and bone formation. In this study, complementary DNA (cDNA) microarrays were used to identify and study the expression of novel genes that may be involved in MC3T3-E1 cells' response to 17-ß estradiol. MC3T3-E1 cells were inoculated in minimum essential media alpha (α-MEM) cell culture supplemented with 17-ß estradiol at different concentrations and for different time periods. MC3T3-E1 cells treated with 10⁻8 mol⋅L⁻¹ 17-ß estradiol for 5 days exhibited the highest proliferation and alkaline phosphatase (ALP) activity; thus, this group was chosen for microarray analysis. The harvested RNA was used for microarray hybridisation and subsequent real-time reverse transcription polymerase chain reaction (RT-PCR) to validate the expression levels for selected genes. The microarray results were analysed using both functional and pathway analysis. In this study, microarray analysis detected 5403 differentially expressed genes, of which 1996 genes were upregulated and 3407 genes were downregulated, 1553 different functional classifications were identified by gene ontology (GO) analysis and 53 different pathways were involved based on pathway analysis. Among the differentially expressed genes, a portion not previously reported to be associated with the osteoblast response to oestrogen was identified. These findings clearly demonstrate that the expression of genes related to osteoblast proliferation, cell differentiation, collagens and transforming growth factor beta (TGF-ß)-related cytokines increases, while the expression of genes related to apoptosis and osteoclast differentiation decreases, following the exposure of MC3T3-E1 cells to α-MEM supplemented with 17-ß estradiol. Microarray analysis with functional gene classification is critical for a complete understanding of complementary intracellular processes. This microarray analysis provides large-scale gene expression data that require further confirmatory studies.

The early phase response of rat alveolar bone to traumatic occlusion.

OBJECTIVES: Occlusal trauma is an important factor to influence alveolar bone remodelling, the effect of which includes many cytokines and signalling pathways. However, the exact mechanism of the traumatic stimulus for alveolar remodelling is still unclear. The purpose of the present study was to investigate the early responses of alveolar osteocytes to occlusal trauma through genome-wide microarray. METHODS: The occlusal surface of the upper left first molar of rat was raised by placing a stainless steel wire to induce occlusal trauma in the lower left first molar. After 24 h, we took out the alveolar bone tissue of the first molars at the both sides of rats' lower jaws under anaesthesia. The different gene expressions were showed by genome-wide microarray, which comprises about 27,000 genes and the results were examined by quantitative RT-PCR. RESULT: Of the approximately 27,000 genes, the expression of 586 genes was strongly changed. These findings clearly demonstrated that in the early response of the alveolar bone to occlusal trauma, the expression of osteoblast, collagens, bone mineralization, bone remodelling and WNT, TGF-ß pathway related cytokines decreased, and osteoclast-specific cytokines have no significant changes in expression. CONCLUSION: These results suggested that at early phase of the occlusal trauma, osteogenesis in rat's alveolar bone was inhibited, and osteoclastogenesis was not significant.

[The inspiration of comprehensive quality related cutting-edge curriculum of the University of California, Los Angeles School of Dentistry].

In this article, the author introduced three course of comprehensive quality training set up in the University of California, Los Angeles School of Dentistry (UCLA), named "introduction to behavioral science", "patient management", "methods in evidence-based dentistry". In order to provide reference for our medical reform of dental students, the content of the three courses were provided and the importance of comprehensive quality training was evaluated. The curriculum type, number of hours and time to deliver were compared between UCLA and School of Stomatology, Shandong University. It was found that the comprehensive quality training-related curriculum, offered in Shandong University covered fewer content, fewer number of hours and delivered later. Therefore, the author suggests the domestic dental institutions set up the three cutting-edge courses integrated with clinical practice as well. Supported by Teaching Reform Project of Shandong University (2009174).

[The revelation from three international medical education standards to education of physician-patient communication].

The ability of manipulating physician-patient communication is of great significance in medical practice and undoubtedly needed to be developed during medical education. The importance and request of physician-patient communication in medical education has been definitely prescribed in three international standards stipulated respectively by three international medical education organizations. In this article, the author attempted to reveal the deficiency of Chinese medical education on physician-patient communication by studying the three international standards as mentioned. And some measures had also been recommended to improve the conditions: setting up physician-patient communication curriculums among students; emphasizing the training of the skills in internship during undergraduate study period; adding physician-patient communication contents in the Practice Physician Qualification Test; and so on. The improvement of communication skills in basic medical education is the primary part for the progress of whole medical area. Supported by Teaching Reform Project of Shandong University (Grant No.200954,2009174,2009226).

[Analysis of the curriculum of the University of California, Los Angeles School of Dentistry].

By comparative analysis of the curriculum of the University of California, Los Angeles (UCLA) School of Dentistry with Shandong University College of Stomatology, this paper explored what could be used as reference for Chinese dental educators. The curriculum characteristics and teaching ways in UCLA was analyzed; the dental courses of UCLA were compared with Shandong University, fourteen courses opened in UCLA were not opened in Shandong University; eight forefront courses selected from the fourteen courses were introduced. The analysis showed that in certain degree the curriculum characteristics and teaching ways of UCLA could be used for reference and fourteen forefront courses were also necessary. It's suggested to increase the proportion of dental courses, increase hours for experiments, combine theories and experiments tightly and gradually open forefront courses such as Clinical Applications of Dental Morphology, Esthetic Dentistry, Geriatric Dentistry, Hospital Dentistry, Health Policy Issues, Methods in Evidence-based Dentistry, Introduction to Behavioral Science, Patient Management and so on within domestic universities.

How to deal with esthetically overcritical patients who need complete dentures: a case report.

AIM: The purpose of this report is to present a strategy for making a diagnosis and providing appropriate treatment for denture patients with high esthetic demands. BACKGROUND: Some edentulous patients have critical requirements for the esthetic aspect of dentures. REPORT: A 55-year-old edentulous female presented with a complaint of dissatisfaction with the appearance of two sets of old dentures. A complex method was used during the fabrication of a new set of dentures in order to meet her demand for esthetics. SUMMARY: This method essentially improves the mutual communication and cooperation between dentists and patients; therefore, it improves satisfaction of the patients.

A modification of a direct technique for the fabrication of posts and using wax pattern.

This new direct technique for the fabrication of posts and cores using a wax pattern is easy to manipulate. It requires no special armamentarium and is appropriate for various situations. It provides the advantage of a direct technique and ensures the post pattern's precise fit. It also avoids the disadvantage of other direct techniques, the limitation of the direction of the cores by the placement of the broaches, the pins, or the prefabricated dowels.

[Experimental study on the reconstruction of bone defects in vivo and the osteoinduction with degradation products of alpha-tricalcium phosphate cements in vitro].

OBJECTIVE: This study was aimed to clarify the characteristics of alpha-tricalcium phosphate cements in reconstructing bone defects and the action of degradation products of cements in vitro. METHODS: The defect (diameter 1.5 cm) was created in the calvaria of rabbit. Alpha-tricalcium phosphate cements were planted in the treatment groups. All groups were observed by histological examination and roentgenography. Bone marrow stromal cells (BMSc) were cultured in the degradation products of cements in vitro, and were observed by means of cytology and ALP. RESULTS: Degradation of artificial bone, new bone formation, and osteogenesis between artificial bone particles were observed at 12 weeks after implantation. Osteoinduction was observed in vitro. CONCLUSION: Alpha-tricalcium phosphate cements have good biocompatibility, osteoinductivity and degradability, and are ideal bone substitute material for reconstruction.

[Clinical evaluation of masticatory function of implant supported dentures in partially edentulous patients].

OBJECTIVE: To evaluate the masticatory efficiency of implant supported dentures in partially edentulous patients and the patients' satisfaction on masticatory function. METHODS: The masticatory efficiency of implant supported dentures of 22 patients were tested. The questionnaire of the patients' satisfaction about masticatory function had also been collected. The correlativity of the masticatory efficiency of implant supported dentures and the scores evaluated by patients on masticatory function were analyzed. RESULTS: There were no differences in masticatory efficiency between implant supported denture and non-implant supported denture (natural teeth and porcelain-fused-to-metal fixed bridges). The patients gave high scores to the satisfaction about masticatory function in the questionnaire. But the test results of masticatory efficiency were not related with the scores evaluated by patients. CONCLUSION: The implant supported denture could meet the requirement of normal masticatory function. The patients were satisfactory with the masticatory function of implant supported dentures, but the patients' subjective evaluation about masticatory function was probably influenced by varied factors.

[Investigation of the expression of calcitonin receptor mRNA in human osteoclasts on deciduous teeth].

OBJECTIVE: To investigate the expression of calcitonin receptor mRNA in the osteoclasts of the resorbing deciduous teeth. METHODS: After fixing the collected deciduous teeth, toluidine blue was performed and tartrate-resistant acid phosphatase (TRAP) staining was used to identify the osteoclasts on the resorbing surface of human deciduous teeth and in situ hybridization of calcitonin receptor mRNA to show its existence. RESULTS: There were a number of TRAP positive osteoclasts on the root surface which showed the expression of calcitonin receptor mRNA. CONCLUSION: On the resorbing surface of human deciduous teeth there are osteoclasts that express calcitonin receptor mRNA, so it is feasible to use this kind of osteoclast to test the effect of external factors on the expression of CTR mRNA.

[Evaluation of matrix metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 levels in peri-implant sulcular fluid].

OBJECTIVE: To investigate the levels of MMP-9 and TIMP-1 in healthy and diseased peri-implant tissue. METHODS: Fifty-one implants in 39 patients were selected and divided into the healthy group and the inflammatory group according to the absence or presence of gingival redness, bleeding on probing, and progressive horizontal absorption of alveolar bone. The clinical parameters included: depth of gingival pocket(PD), plaque & calculus index (PLI), gingival bleeding index (GBI), and MMP-9, TIMP-1 levels in peri-implant sulcular fluid (PISF). RESULTS: PD, PLI, GBI and MMP-9 levels were significantly higher in inflammatory group than in healthy group (P < 0.001). CONCLUSION: MMP-9 level in PISF was closely associated with the clinical parameters.