Visual psychosocial profiling of Chinese temporomandibular disorder pain patients and correlations with somatosensory function.

BACKGROUND: Psychosocial function of Chinese temporomandibular disorders (TMD) pain patients and the correlation with somatosensory function has not been sufficiently studied. OBJECTIVE: The study aims at assessing the psychosocial function of Chinese TMD pain patients by visualisation method and evaluating the correlations with somatosensory function quantitatively. METHODS: The Symptom Checklist 90 (SCL-90) questionnaire and standardised quantitative sensory testing (QST) were administered to 70 Chinese TMD pain patients and age- and gender-matched healthy controls (HCs). Of these, 40 TMD arthralgia patients received QST before and after medication. Psychosocial and somatosensory parameters were transformed into standardised scores. Differences within groups were assessed through t tests. Correlations between psychosocial and somatosensory profiles were explored through correlation analyses with Bonferroni correction for multiple comparisons. RESULTS: 100% of the Chinese TMD pain patients exhibited psychosocial distress in contrast to HCs. Anger and hostility showed negative correlation with the thermal nonnociceptive parameter (thermal sensory limen, p =.002) and nociceptive parameters (cold pain threshold and pain pressure threshold, p<.001). Correlation analysis indicated that cold detection threshold was negatively correlated with somatization and mechanical pain sensitivity had a negative correlation with anger and hostility through medical treatment (p <.001). CONCLUSIONS: Visual psychosocial profiles provided an easy overview of psychosocial function in Chinese TMD pain patients. Anger and hostility was associated with increased thermal nonnociceptive and nociceptive sensitivity to stimuli. Psychosocial distress might be negatively associated with TMD treatment response which indicated a possible need for psychological intervention during treatment.

Dissecting neural circuits from rostral ventromedial medulla to spinal trigeminal nucleus bidirectionally modulating craniofacial mechanical sensitivity.

Chronic craniofacial pain is intractable and its mechanisms remain unclarified. The rostral ventromedial medulla (RVM) plays a crucial role in descending pain facilitation and inhibition. It is unclear how the descending circuits from the RVM to spinal trigeminal nucleus (Sp5) are organized to bidirectionally modulate craniofacial nociception. We used viral tracing, in vivo optogenetics, calcium signaling recording, and chemogenetic manipulations to investigate the structure and function of RVM-Sp5 circuits. We found that most RVM neurons projecting to Sp5 were GABAergic or glutamatergic and facilitated or inhibited craniofacial nociception, respectively. Both GABAergic interneurons and glutamatergic projection neurons in Sp5 received RVM inputs: the former were antinociceptive, whereas the latter were pronociceptive. Furthermore, we demonstrated activation of both GABAergic and glutamatergic Sp5 neurons receiving RVM inputs in inflammation- or dysfunction-induced masseter hyperalgesia. Activating GABAergic Sp5 neurons or inhibiting glutamatergic Sp5 neurons that receive RVM projections reversed masseter hyperalgesia. Our study identifies specific cell types and projections of RVM-Sp5 circuits involved in facilitating or inhibiting craniofacial nociception respectively. Selective manipulation of RVM-Sp5 circuits can be used as potential treatment strategy to relieve chronic craniofacial muscle pain.

Descending serotonergic modulation from rostral ventromedial medulla to spinal trigeminal nucleus is involved in experimental occlusal interference-induced chronic orofacial hyperalgesia.

BACKGROUND: Dental treatment associated with unadaptable occlusal alteration can cause chronic primary myofascial orofacial pain. The serotonin (5-HT) pathway from the rostral ventromedial medulla (RVM) exerts descending modulation on nociceptive transmission in the spinal trigeminal nucleus (Sp5) and facilitates chronic pain. The aim of this study was to investigate whether descending 5-HT modulation from the RVM to the Sp5 is involved in the maintenance of primary myofascial orofacial hyperalgesia after persistent experimental occlusal interference (PEOI) or after delayed removal of experimental occlusal interference (REOI). METHODS: Expressions of 5-HT3A and 5-HT3B receptor subtypes in the Sp5 were assessed by immunofluorescence staining and Western blotting. The release and metabolism of 5-HT in the Sp5 were measured by high-performance liquid chromatography. Changes in the pain behavior of these rats were examined after specific pharmacologic antagonism of the 5-HT3 receptor, chemogenetic manipulation of the RVM 5-HT neurons, or selective down-regulation of 5-HT synthesis in the RVM. RESULTS: Upregulation of the 5-HT3B receptor subtype in the Sp5 was found in REOI and PEOI rats. The concentration of 5-HT in Sp5 increased significantly only in REOI rats. Intrathecal administration of Y-25130 (a selective 5-HT3 receptor antagonist) dose-dependently reversed the hyperalgesia in REOI rats but only transiently reversed the hyperalgesia in PEOI rats. Chemogenetic inhibition of the RVM 5-HT neurons reversed the hyperalgesia in REOI rats; selective down-regulation of 5-HT in advance also prevented the development of hyperalgesia in REOI rats; the above two manipulations did not affect the hyperalgesia in PEOI rats. However, chemogenetic activation of the RVM 5-HT neurons exacerbated the hyperalgesia both in REOI and PEOI rats. CONCLUSIONS: These results provide several lines of evidence that the descending pathway from 5-HT neurons in the RVM to 5-HT3 receptors in the Sp5, plays an important role in facilitating the maintained orofacial hyperalgesia after delayed EOI removal, but has a limited role in that after persistent EOI.

Surface Characteristics and Flexural Strength of Porous-Surface Designed Zirconia Manufactured via Stereolithography.

PURPOSE: To design and fabricate zirconia bars with porous surfaces using stereolithography and evaluate their surface characteristics and flexural strengths. MATERIALS AND METHODS: Five groups of zirconia bars (20 mm × 4 mm × 2 mm) with interconnected porous surfaces were designed and manufactured: (i) 400-µm pore size and 50% porosity (D400-P50 group), (ii) 400-µm pore size and 30% porosity (D400-P30 group), (iii) 200-µm pore size and 50% porosity (D200-P50 group), (iv) 200-µm pore size and 30% porosity (D200-P30 group), and (v) 100-µm pore size and 30% porosity (D100-P30 group). Zirconia bars without a porous surface (NP) were used as controls. The surface topographies and pore structures were investigated using scanning electron microscopy and three-dimensional laser microscopy. The printed porosity was calculated using the Archimedes method. Fifteen specimens from each group were subjected to a three-point bending test according to the ISO 6872:2015 standard. A Weibull analysis was performed, and the fractured surfaces were examined using scanning electron microscopy. RESULTS: Zirconia bars with porous surfaces were designed and successfully manufactured. The designed pore size, porosity, and shape of the printed pores were approximately achieved for all the porous surfaces. The flexural strength of the control group was significantly higher than those of the groups with porous surfaces (p < 0.001). For the same porosity, groups with a pore size of 400 µm exhibited a lower flexural strength than the other groups (p<0.001). Additionally, for the same pore-size design, the flexural strengths of group D400-P50 and D400-P30 exhibited no significant differences (p = 0.150), while the flexural strengths of D200-P30 were significantly higher than that of the D200-P50 group (p = 0.043). The control group and D400-P50 group had higher Weibull moduli than the other groups. The fractography of the specimens with porous surfaces indicated more than one crack origin, mainly owing to defects, including pores and cracks. CONCLUSION: Zirconia bars with porous surfaces were successfully designed and fabricated using the stereolithography technique. Although porous surfaces may be advantageous for osteogenesis, the porous-surface design can reduce the flexural strength of the printed zirconia bars. By reducing the pore size, controlling the porosity, and improving the printing accuracy, a higher strength can be achieved.

A three-dimensional printed assembled sleeveless guide system for fiber-post removal.

This report describes a technique to develop a three-dimensional printed assembled sleeveless guide system to aid the fiber-post removal in a safe and efficient way. The surface and volume data of the dentition containing the targeted tooth were acquired with optical scanners and cone-beam computed tomography. The virtual path of the fiber-post removal was determined and integrated with a guide prototype with a cylindrical passage. The prototype data was split into two separate parts, combined with the matched pin and jack structures to facilitate the assembly. A guide tube was generated based on the axis of the cylindrical passage, split into three units, and combined with the previously processed data with connectors to form the finalized guide system. The adaptor for the head of handpiece was designed to facilitate the guidance. All the finalized data were printed with titanium alloy. The fiber-post of the upper right central incisor was successfully removed with the aid of this assembled sleeveless guide system that guides the handpiece rather than the rotary instrument.

Somatosensory and trigeminal pathway abnormalities in Chinese patients with trigeminal neuralgia.

This study aimed to evaluate somatosensory function in Chinese patients with trigeminal neuralgia (TN) using a standard quantitative sensory testing (QST) battery and electrophysiological tests consisting of contact heat-evoked potentials (CHEPs) and blink reflex (BR). Twenty patients with TN and 20 sex- and age-matched healthy controls were recruited for this study. A standard QST protocol recommended by the German Research Network on Neuropathic Pain was carried out on the patients' painful and contralateral faces, the controls' right faces, and all participants' right hands. The CHEPs and BR were recorded at the Cz electrode and bilateral lower bellies of the orbicularis oculi, respectively, with thermal stimuli applied to both sides of the patient's face and the control's right face. The cold detection threshold, heat pain threshold, and mechanical pain threshold on the painful face were lower than those of healthy controls (P < 0.05), whereas the cold pain threshold and mechanical detection threshold were higher (P < 0.05) on the painful faces than those of the contralateral faces from patients or healthy controls. Mechanical pain sensitivity was higher in both test sites than in healthy controls (P < 0.05). Significantly longer N latencies (P < 0.05) and lower N-P amplitudes (P < 0.01) were detected in the patients' painful sites than in the contralateral sites and those of healthy controls. Comprehensive somatosensory abnormalities were found in painful facial sites in patients with TN, suggesting disturbances in the processing of somatosensory stimuli. Deficiencies in electrophysiological tests further revealed unilaterally impaired function of the trigeminal pathway in TN patients.

Accuracy of a chairside, fused deposition modeling three-dimensional-printed, single tooth surgical guide for implant placement: A randomized controlled clinical trial.

PURPOSE: To compare the accuracy of chairside, fused deposition modeling (FDM) three-dimensional (3D)-printed surgical guides with that of stereolithographic guides for implant placement in single edentulous sites within a clinical setting. MATERIALS AND METHODS: A total of 28 participants with 30 single posterior edentulous sites were included. The sites were randomized into a FDM 3D-printed surgical guide group (test) or stereolithographic guide group (control) of equal size (n = 15). In both groups, digital implant planning was performed using data from cone beam-computed tomography and intraoral scans. The test group's surgical guides were fabricated using a chairside, FDM 3D-printer; those in the control group were fabricated using a light-curing 3D-printer. Postoperative intraoral scans were used to obtain the 3D position of the implants. Compared to preoperative design, the angular, 3D, mesiodistal, buccolingual and apicocoronal deviations at the implant shoulder and apex were recorded. RESULTS: The workflow for the design and chairside fabrication of implant guides was established. The mean angular deviations of the test and control group were (4.23 ± 2.38) ° and (4.13 ± 2.42) ° (p > .05), respectively. The respective 3D deviations at the implant shoulder were (0.70 ± 0.44) mm and (0.55 ± 0.27) mm (p > .05); those at the implant apex were (1.25 ± 0.61) mm and (1.11 ± 0.54) mm (p > .05). The mesiodistal, buccolingual, and apicocoronal deviations at the implant shoulder and apex did not significantly differ between the groups (p > .05). CONCLUSIONS: Implants for single posterior edentulous spaces were placed as accurately with the test guide as with the control. Further research under more complex situations involving multiple missing teeth is needed.

Digital Determination and Recording of Edentulous Maxillomandibular Relationship Using a Jaw Movement Tracking System.

PURPOSE: To establish a direct digital method for determining and recording edentulous maxillomandibular relationship using a custom-made jaw movement tracking system and evaluate its accuracy. MATERIALS AND METHODS: A novel jaw tracking system was used to record the trajectory of habitual opening-closing jaw movement, and mandibular rest position (MRP) in 10 edentulous patients. 3D surface scanning was performed on the conventional maxillomandibular impressions and facial structures of patients in MRP. The multisource data were registered using a custom-made recording tool. A plane parallel to the ala-tragus and horizontal lines was constructed 2 mm above the MRP, and its vertical position was used to determine the vertical relationship. The intersections of the trajectory passing through the plane were located, and their density distributions were analyzed. The coordinates of highest density, which presented the highest repeatability of jaw movement, were used to construct the digital maxillomandibular relationship (test group). The maxillomandibular relationship of the new complete dentures with artificial teeth in the intercuspal position was defined as the control group. The displacements of the anterior reference point and 3D deviations of the entire mandibular arch were measured and compared between the test and control groups using a Wilcoxon signed-ranks test and a one-sample t-test, respectively. RESULTS: With reference to the centric relationship position, the maximum displacements of the anterior reference points were in the horizontal anteroposterior direction for both groups, and there were no significant differences. Compared to the control group, the 3D deviations of the entire mandibular arch in the test group were significant (95% confidence interval: 0.76 mm to 1.35 mm, p < 0.001). CONCLUSIONS: By analyzing the individual trajectory features obtained by the in-house developed jaw tracking system, a digital method for determining and recording edentulous maxillomandibular relationships was established; however, the accuracy needs to be further improved.

Occlusal change in posterior implant-supported single crowns and its association with peri-implant bone level: a 5-year prospective study.

OBJECTIVES: This study aims to analyze the 5-year occlusal change in posterior implant-supported single crowns and the association between the relative occlusal force (ROF) and peri-implant bone level. MATERIALS AND METHODS: Partially edentulous patients who had received implant-supported single crowns in the posterior region were included. Occlusal examinations with a computerized occlusion analysis system were conducted at 0.5, 3, 6, 12, 24, 36, 48, and 60 months after delivery of the implant-supported single crown. The ROFs of implant-supported single crowns, mesial adjacent teeth, and control natural teeth were recorded. Intraoral periapical radiographs were taken at each follow-up time to evaluate marginal bone level (MBL). Ordinary least square regression was used to analyze the association between ROF and MBL. RESULTS: Thirty-seven posterior implant-supported single crowns in 33 participants (23.9 to 70.0 years) were followed up for 0.5 to 60 months [(42.4 ± 26.0) months]. The ROF of implant-supported single crowns increased from 2 weeks to 3 months (P < 0.01) and increased continuously between all two sequential time points from 6 to 36 months, with significant differences (P < 0.05). Then ROFs of implant-supported single crowns were significantly higher than those of control teeth at 48 and 60 months (P < 0.05). Regression analysis showed that ROF was significantly associated with MBL with a coefficient of 0.008 (P < 0.05). CONCLUSION: The ROFs of posterior implant-supported single crown have significant change during 5 years' follow-up. The association between ROF and MBL has limited clinical significance. TRIAL REGISTRATION: Chinese Clinical Trial Registry: ChiCTR-ROC-17012240. CLINICAL RELEVANCE: The occlusion of implant-supported single crowns should be carefully monitored during follow-up examinations, and occlusal adjustment should be considered to prevent overloading.

Quantitative evaluation of edentulous maxillomandibular relationship record using diagnostic complete dentures fabricated by CAD and 3D printing.

PURPOSE: The present study aimed to quantitatively evaluate the accuracy of the edentulous maxillomandibular relationship record for diagnostic complete dentures fabricated using computer-aided design (CAD) and three-dimensional (3D) printing. METHODS: Six edentulous patients were enrolled. The maxillomandibular relationship obtained from diagnostic complete dentures (DiaCD test group), that obtained from complete dentures with artificial teeth in the intercuspal position (CD control group), and the centric relationship acquired by gothic arch tracing (CR standard group) were recorded, and 3D surface scanning was performed on these records. Using the CR standard group as a reference, the DiaCD test and CD control group displacements were measured in the horizontal antero-posterior, horizontal right-and-left, and vertical directions. The displacements for the DiaCD test group were compared with those for the CD control group using the Wilcoxon matched-pairs signed rank test. RESULTS: In terms of centric relationship, the 95% confidence interval of displacement in the horizontal antero-posterior direction was (0.54-1.89) mm in the DiaCD test group and (0.32-1.34) mm in the CD control group. The inter-group difference was significant (P = 0.03). CONCLUSION: It is feasible to record the edentulous maxillomandibular relationship using diagnostic complete dentures fabricated by CAD/3D printing, but the protrusion of edentulous patients should not be neglected.

Astrocytes in the rostral ventromedial medulla contribute to the maintenance of oro-facial hyperalgesia induced by late removal of dental occlusal interference.

BACKGROUND: Astrocytes in the rostral ventromedial medulla (RVM) contribute to descending pain modulation, but their role in oro-facial pain induced by persistent experimental dental occlusal interference (PEOI) or following EOI removal (REOI) is unknown. OBJECTIVE: To explore the involvement of RVM astrocytes in PEOI-induced oro-facial hyperalgesia or its maintenance following REOI. METHODS: Male rats were randomly assigned into five groups: sham-EOI, postoperative day 6 and 14 of PEOI (PEOI 6 d and PEOI 14 d), postoperative day 6 following REOI on day 3 (REOI 3 d) and postoperative day 14 following REOI on day 8 (REOI 8 d). The nociceptive head withdrawal threshold (HWT) and activities of RVM ON- or OFF-cells were recorded before and after intra-RVM astrocyte gap junction blocker carbenoxolone (CBX) microinjection. RVM astrocytes were labelled immunohistochemically with glial fibrillary acidic protein (GFAP) and analysed semi-quantitatively. RESULTS: Persistent experimental dental occlusal interference-induced oro-facial hyperalgesia, as reflected in decreased HWTs, was partially inhibited by REOI at day 3 but not at day 8 after EOI placement. Increased GFAP-staining area occurred only in REOI 8 d group in which CBX could inhibit the maintained hyperalgesia; CBX was ineffective in inhibiting hyperalgesia in PEOI 14 d group. OFF-cell activities showed no change, but the spontaneous activity and responses of ON-cells were significantly enhanced that could be suppressed by CBX in REOI 8 d group. CONCLUSION: Rostral ventromedial medulla astrocytes may not participate in PEOI-induced oro-facial hyperalgesia or hyperalgesia inhibition by early REOI but are involved in the maintenance of oro-facial hyperalgesia by late REOI.

Accuracy of recording edentulous jaw relations by using an optical jaw tracking system: An in vitro study.

PURPOSE: To establish a recording method for edentulous jaw relations and to perform quantitative accuracy evaluation in vitro. MATERIALS AND METHODS: Maxillary and mandibular edentulous arch models and complete dentures were mounted on an articulator, simulating protrusion (A), left and right laterotrusion (B and C), and small opening jaw relations (D), aided by metal foil wax record. Using the tracking system, 3D trajectories of targets were recorded from intercuspation to A, B, C, and D, then used to rehabilitate digital arch relations of A, B, C, and D in the test group. Axial model surfaces were pasted with six pairs of positioning cylinders. The center points of the bottom surfaces of the cylinders in A, B, C, and D were measured to rehabilitate digital arch relations in the control group. With the maxilla as the common area, arch relations of the test group were registered in the control group; 3D deviations of the mandible were calculated, and displacements in horizontal left/right, horizontal anterior/posterior, and vertical directions were analyzed. RESULTS: 3D deviations of the mandible in A, B, C, and D were 131 ± 39 µm, 133 ± 44 µm, 120 ± 51 µm, and 112 ± 52 µm, respectively. Mean absolute values of displacements of the mandible were less than 200 µm. CONCLUSION: By using the optical jaw tracking system, the accuracy of jaw relation records as measured on an articulator was acceptable for clinical demand. Further investigations among patients are required to clinically verify the results of this study.

Genistein reverses the effect of 17ß-estradiol on exacerbating experimental occlusal interference-induced chronic masseter hyperalgesia in ovariectomised rats.

BACKGROUND: Oro-facial pain is more prevalent in women than in men, and oestrogen may underlie this sex difference. Genistein reversed the potentiation of 17ß-estradiol (E2) on glutamate-induced acute masseter nociceptive behaviour, but its role in dental experimental occlusal interference (EOI)-induced chronic masseter hyperalgesia remains unclear. OBJECTIVE: This study aimed to investigate sex differences, and to explore the role and underlying mechanisms of genistein in E2-potentiated EOI-induced chronic masseter hyperalgesia in rats. METHODS: Female and male rats were prepared to compare the sex differences of masseter hyperalgesia induced by EOI using a 0.4-mm-thick metal crown. Female rats were ovariectomised (OVX) and treated with E2 and genistein, followed by EOI. The head withdrawal threshold (HWT) was examined to assess masseter sensitivity. The protein expression of transient receptor potential vanilloid-1 (TRPV1) in the trigeminal ganglion (TG) was detected using western blotting. Immunofluorescence staining was used to reveal the colocalisation of oestrogen receptors (ERs) with TRPV1 and the percentage of TRPV1-positive neurons in the TG. RESULTS: To some extent, female rats displayed enhanced sensitivity to EOI-induced chronic masseter hyperalgesia compared with males. Female rats showed the lowest HWT in the pro-oestrus phase. Pre-treatment with genistein antagonised E2 potentiation in EOI-induced masseter hyperalgesia and blocked the effect of E2 by downregulating TRPV1 protein expression and the percentage of TRPV1-positive neurons in the TG. CONCLUSION: Female rats showed greater masseter hyperalgesia than males under EOI. Genistein antagonised the facilitation of EOI-induced chronic masseter hyperalgesia by E2 probably through inhibiting TRPV1 in the TG.

A Digital Technique to Fabricate Segmental Individual Tooth Trays for Making an Impression of Multiple Crown Preparations.

A digital technique is described for designing and fabricating segmental individual tooth trays that can be used to make an impression of multiple preparations with high accuracy and efficiency. A digital model of prepared dentition was acquired. The segmental individual tooth trays with retention attachments and tissue stops were designed and 3D printed with light-polymerizing resin. The segmental impression of each section of the prepared dentition was made with the corresponding individual tooth tray loaded with the impression material. A final overall impression was made to pick up the segmental individual tooth trays with a full arch tray.

A digitally designed and 3D printed individual tooth tray for taking subgingival impression of complete crown preparation.

A digital technique for designing and fabricating an individual tooth tray used for taking subgingival impression of complete crown preparation was described. The digital model of required dentition region was obtained before performing crown preparation. An individual tooth tray with retention attachments was designed and printed with plastic material. After conducting crown preparation, the individual tooth tray loaded with the final impression material was placed onto the abutment to deliver the impression material subgingivally. A final overall impression was made with full arch stock tray to pick up the individual tooth tray with the accurate impression of abutment.

17ß-Estradiol Exacerbated Experimental Occlusal Interference-Induced Chronic Masseter Hyperalgesia by Increasing the Neuronal Excitability and TRPV1 Function of Trigeminal Ganglion in Ovariectomized Rats.

Pain symptoms in temporomandibular disorders (TMD) predominantly affect reproductive women, suggesting that estrogen regulates pain perception. However, how estrogen contributes to chronic TMD pain remains largely unclear. In the present study, we performed behavioral tests, electrophysiology, Western blot and immunofluorescence to investigate the role and underlying mechanisms of estrogen in dental experimental occlusal interference (EOI)-induced chronic masseter mechanical hyperalgesia in rats. We found that long-term 17ß-estradiol (E2) replacement exacerbated EOI-induced masseter hyperalgesia in a dose-dependent manner in ovariectomized (OVX) rats. Whole-cell patch-clamp recordings demonstrated that E2 (100 nM) treatment enhanced the excitability of isolated trigeminal ganglion (TG) neurons in OVX and OVX EOI rats, and EOI increased the functional expression of transient receptor potential vanilloid-1 (TRPV1). In addition, E2 replacement upregulated the protein expression of TRPV1 in EOI-treated OVX rats. Importantly, intraganglionic administration of the TRPV1 antagonist AMG-9810 strongly attenuated the facilitatory effect of E2 on EOI-induced masseter mechanical sensitivity. These results demonstrate that E2 exacerbated EOI-induced chronic masseter mechanical hyperalgesia by increasing TG neuronal excitability and TRPV1 function. Our study helps to elucidate the E2 actions in chronic myogenic TMD pain and may provide new therapeutic targets for relieving estrogen-sensitive pain.

Occlusal Assessment of Zirconia Crowns Designed with the Digital Articulator and Traditional Methods.

PURPOSE: To evaluate and compare the occlusal fit of zirconia crowns designed using a digital articulator method and the traditional method in a self-controlled clinical trial. MATERIALS AND METHODS: Two zirconia crowns each were prepared for 12 patients with a single posterior tooth defect using two different methods: a digital articulator method and the traditional method. In the traditional method, casts were scanned using a model scanner, and the relative positions of the maxillary and mandibular arches were determined by the intercuspal occlusion of the casts. In the digital articulator method, casts were mounted on a mechanical articulator and scanned, and the relative positions were determined by their respective positions in the articulator. Additional dynamic occlusal adjustments of the digital articulator crowns were performed. Both groups of zirconia crowns were milled in a five-axis milling machine. The time required for occlusal adjustments, the occlusal contacts, the occlusal contact distributions, the number of occlusal contacts, the relative occlusal forces, and patient satisfaction (visual analog scale score) were evaluated. Wilcoxon test, McNemar test, and paired t test were used to compare the parameters between the two methods. RESULTS: The occlusal adjustment times for the digital articulator and traditional method crowns were 327 ± 226 seconds and 395 ± 338 seconds, respectively (P > .05). There were no significant differences in occlusal contacts, occlusal contact distributions, number of occlusal contacts, relative occlusal forces, or VAS scores between the two methods (P > .05). CONCLUSION: A digital articulator method for single-crown restoration was applied successfully. Crowns fabricated using a digital articulator or the traditional method can achieve acceptable occlusal fit for single-crown restorations.

A Novel Bionic Extracellular Matrix Polymer Scaffold Enhanced by Calcium Silicate for Bone Tissue Engineering.

A novel porous calcium silicate (CS)-enhanced small intestinal submucosa (SIS) scaffold was prepared by freeze-drying to mimic the natural extracellular matrix environment for bone tissue engineering. The micro-morphology, physicochemical properties, biological characteristics, and effects on osteogenic differentiation in vitro were explored; the effects on promoting bone formation in vivo were evaluated. The composite scaffold had an ideal three-dimensional porous structure. The amount of calcium silicate played a significant role in improving mechanical properties and promoting osteogenic differentiation. The SIS/2CS scaffold promoted proliferation and osteogenic differentiation in human bone marrow mesenchymal stem cells; it also significantly increased osteogenesis in vivo. This novel composite polymer scaffold has potential applications in bone tissue engineering.

Effects of Different Microstructured Surfaces on the Osseointegration of CAD/CAM Zirconia Dental Implants: An Experimental Study in Rabbits.

PURPOSE: To assess different microstructured surfaces created by sandblasting and acid etching in an effort to optimize the osseointegration performance of dental zirconia implants with an optimized surface. MATERIALS AND METHODS: Sixty CAD/CAM zirconia implants were divided into four groups. The control group had no surface treatment after sintering. The other groups had three different types of surface modifications: sandblasting; sandblasting and etching with hydrofluoric acid; and sandblasting and etching with an experimental hot etching solution composed of methanol, 37% hydrochloric acid, and ferric chloride, heated to 100°C and applied for 60 minutes. Commercially available titanium implants with sandblasted and etched surfaces and identical dimensions were employed as a positive control. Surface micromorphologies of implants from the five groups were evaluated. The osseointegration performance of all the implants was assessed in adult New Zealand rabbits based on microcomputed tomography (micro-CT) and histologic analysis. RESULTS: Sandblasting and acid etching with hot etching solution or hydrofluoric acid exhibited moderately rough surfaces with microstructures in both microscale and nanoscale. The sandblasting and etching with hydrofluoric acid group showed the highest surface roughness. Micro-CT revealed a significantly lower mean bone volume/total volume for the control group compared with the other four groups (P < .05). Among the groups, the sandblasting and hydrofluoric acid etching group was the highest, significantly higher than the titanium implant and sandblasting groups (P < .05). The sandblasting and etching with hot etching solution (P = .006) group also showed a significantly higher bone volume/total volume value than the titanium implant group. Histologic analysis revealed significantly higher boneto- implant contact for implants with modified surfaces compared with a sintered surface (P < .05), and no significant difference was found with respect to the sandblasted and etched titanium implants. CONCLUSION: The microstructured surfaces created by sandblasting and acid etching show osseointegration comparable to that of commonly used titanium implants.

Effect of a Standardized Training with Digital Evaluation on the Improvement of Prosthodontic Faculty's Performance in Crown Preparation: A Pre-Post Design.

PURPOSE: Standardized crown preparation is an important competency for prosthodontic faculty especially when they take on the dual role of clinician and clinical teacher. Effects of faculty training for enhancing crown preparation competency are seldom reported. This study aimed to analyze the impact of a standardized training workshop with digital evaluation on the dental faculty's performance in crown preparation. MATERIALS AND METHODS: The digitally evaluated grades of anterior (the maxillary right central incisor) and posterior (the mandibular left first molar) tooth preparations made by 76 participants who accomplished all six training tasks were collected, including off-site and on-site exercises before the didactic lecture and live demonstration, three rounds of practices with digital feedback, and a final test. Grades of preparations performed in the on-site exercise were adopted as pre-training scores, and those in the final test as post-training scores. Total scores and marks deducted for the parameters including amount of reduction, margin line, and taper were compared among each training task. RESULTS: The post-training scores of both anterior and posterior tooth preparations increased significantly more than the pre-training scores. The average increased score proportion was 22.95% ± 4.17% for anterior tooth preparations, and 21.78% ± 3.68% for posterior tooth preparations. For anterior tooth preparations, total scores and the parameters except taper significantly improved in the first practice and maintained the same level for the next sessions. Total scores and all parameters for posterior tooth preparations exhibited continual improvement during the training process. CONCLUSION: Standardized training can further improve dental faculty's crown preparation performance in a moderate way. Individual design for crown preparation training can be considered based on different tooth positions. Providing such training will aid the calibration of clinical teaching behavior and the elevation of clinical operative standards for prosthodontic faculty.