[Clinical outcome of single posterior implant-supported monolithic zirconia crowns fabricated using full digital workflow and conventional workflow: a 3-year follow-up]

Objective: To compare the clinical performance of posterior single implant-supported monolithic zirconia crowns fabricated by full digital workflow and that of those fabricated by conventional workflow. Methods: This is prospective clinical research. Thirty-five patients who participated in a previous study during August 2017 to October 2018 at Department of Prosthodontics, Peking University School and Hospital of Stomatology were included in this 3-year follow-up study. The 35 patients, 17 females and 18 males, aged (49.0±15.4) years (24-86 years old), was allocated into two groups. In the full digital workflow group, intraoral scanning was taken immediately after implant placement, and a full zirconia implant crown was fabricated using model-free computer aided design/computer aided manufacturing (CAD/CAM) procedure (n=14). In the conventional group, a conventional impression was taken 3 months after implant placement and the stone model was produced. A full zirconia implant crown was fabricated using conventional model-based procedure (n=21). Three years following crown delivery, all the prostheses were evaluated in the aspect of color, surface roughness, contour and marginal integrity using modified US Public Health Service criteria (MUSPHS criteria). The soft and hard tissue around implant was evaluated using modified plaque index, probing depth (PD), number of implants with bleeding on probing, marginal bone loss (MBL). The biological and mechanical complication were also recorded. Statistical analysis was performed using independent samples t test, Mann-Whitney U test and Fisher's exact test. Results: The total survival rate of prosthesis and implant was 100% (35/35). No significant difference in MUSPHS criteria ratings on color, surface roughness, contour and marginal integrity of these crowns were found between the full digital workflow group and the conventional group (P>0.05). Sixteen out of the 35 crowns had a contour score of B due to loss of interproximal contact. Ten out of the 35 crowns had the screw hole sealing resin sinking or falling off, four in the full digital workflow group and six in the conventional group. There was no significant difference in the rate of prostheses mechanical complications between the two groups (P=1.000). For all the implants, there was no significant difference in MBL, PD, the modified plaque index, and number of implants with bleeding on probing between the two groups (U=119.50,133.00,142.50, t=-0.53, P>0.05). Conclusions: The clinical performance of implant-supported posterior single monolithic zirconia crowns fabricated by full digital workflow was stable. There was no significant difference in the clinical performance of the single implant crowns between the full digital workflow group and the conventional group.

[Treatment planning and key points in clinical procedure of implant overdenture for edentulous patients]

Many randomized controlled clinical trials have reported that implant overdentures provided edentulous people with better retention, stability, and masticatory performance than conventional complete dentures did. The design of implant overdentures for edentulous jaws should be based on comprehensive consideration of factors such as anatomic structure, alveolar bone resorption, inter-arch distance, choice of implant number/distribution and suprastructure. During the clinical procedure, timing of attachment connection, choice of impression technique, methods of maxilla-mandibular relationship registration, wax-up try-in, and prostheses delivery should be determined according to the type of implant overdentures. The appropriate choices and conduction of the above-mentioned procedures can guarantee the long-term success of the prostheses. This review elaborates on the clinical significance, treatment design, key steps in clinical procedure of implant overdenture, and summarizes follow-up and maintenance following denture delivery.

Long Non-Coding RNA (lncRNA) X-Inactive Specific Transcript (XIST) Plays a Critical Role in Predicting Clinical Prognosis and Progression of Colorectal Cancer

Background

Long non-coding RNAs (lncRNAs) participate in all cancer biology processes of cells. Although functions and associated mechanisms of lncRNAs have been proven in colorectal cancer (CRC), the roles of lncRNA X-inactive specific transcript (XIST) have not been clearly investigated in CRC.

Material/Methods

Expression of XIST was detected by quantitative real-time PCR (qRT-PCR) assay in CRC cell lines and 196 clinical samples. Correlations between XIST expression and CRC clinicopathological features were analyzed. Log-rank test and Kaplan-Meier test were performed to assess and compare the prognoses of patients with higher and lower expression of XIST. The multivariate Cox regression and univariate Cox regression were conducted to evaluate the risk factors for prognosis of CRC.

Results

lncRNA XIST was upregulated in CRC cells lines and tissues (p<0.05). Statistical analysis found high XIST expression was correlated with larger tumor size, N1, M1, and topography lymph node metastasis (TNM) III+IV stage of CRC. Moreover, higher expression of XIST could predict poor progression-free survival (PFS) and poor overall survival (OS) of CRC patients. The M1 stage and high expression of XIST were proven to be independent risk factors for poor prognosis (p<0.05).

Conclusions

XIST is upregulated in CRC and is significantly correlated with CRC clinical progression. lncRNA XIST overexpression predict poor PFS and poor OS for CRC patients. lncRNA XIST can be an independent risk factor for CRC prognosis, and could be a potential therapeutic target and prognostic biomarker for CRC patients.

[Oral hygiene maintenance of locator attachments implant overdentures in edentulous population: A longitudinal study]

OBJECTIVE

To investigate the oral hygiene status of edentulous patients with locator attachments implant overdentures (IOD) and to analyze the relationship among daily hygiene behavior, oral hygiene status and peri-implant diseases.

METHODS

Edentulous patients who received IOD treatment with locator attachments from January 2012 to May 2016 were recruited. Clinical and radiographic examinations were conducted to assess the peri-implant tissue status. Modified plaque index (mPLI), sulcus bleeding index (SBI), gingival index (GI), and probing depth (PD) were recorded and peri-implant marginal bone loss (MBL) was measured using paralleling projection technique. Patients' peri-implant oral hygiene maintainence habits were investigated. The correlation between peri-implant diseases and oral hygiene status and behaviors was analyzed.

RESULTS

Fifty patients (125 implants) with an average follow-up time of 22 months (6-54 months) were enrolled. The mean values of mPLI, SBI, and GI were 1.4±1.2, 0.8±0.7, and 0.7± 0.6, respectively. Average PD was (2.2±0.7) mm. Mesial and distal maginal bone resorptions were (1.1±1.1) mm and (0.9±0.9) mm, respectively. The prevalance of mucositis and peri-implantitis of the implants were 49.6% and 0. The prevelance of mucositis in the patients with poor oral hygiene (mPLI≥2) was 11.9 times as much as that of those with adequate oral hygiene (mPLI<1). The patients who performed oral hygiene procedure on attachments at least twice a day achieved much lower mPLI scores than those who cleaned less than twice a day.

CONCLUSION

Oral hygiene condition in the group of patients with implant overdentures was poor, and it contributed to increased risk of peri-implant mucositis. The prevelance of musositis of the paitients with poor oral hygiene was 11.9 times as much as that of those with proper oral hygiene. Patients wearing IOD should pay more attention to the hygiene of the attachments.

[Evaluation of the fabrication deviation of a kind of milling digital implant surgical guides]

OBJECTIVE

To evaluate the deviation of digital implant surgical guides during fabrication process in the Organical Dental Implant (ODI) system.

METHODS

This study included two parts. The first part was the in vitro study. A resin block with a diagnostic template was used for the planning. After cone beam computed tomography (CBCT) scanning, a surgical guide with eight implants was virtually designed using the ODI system. The guide was milled by a 5-axial numerical controlled milling machine, and an optical scanning was taken to digitalize the guide to a standard tessellation language (STL) form. The STL data were then imported into an ODI software and registered with the original design. The deviation of the sleeves between the design and the STL was measured in the ODI software and set as the golden standard. Then the ODI examination table was used to measure the deviation of the guide during fabrication. Examiners A and B measured 10 times separately. The reliability and the validity of the examination table was calculated. The second part was the in vivo study: The deviation during fabrication of 12 guides designed and fabricated by the ODI system were measured using the examination table.

RESULTS

The standard deviation of the deviation measured using the examination table by examiners A and B were all below 0.40 mm (for the shell reference points) and 0.71 degree (for the angles). No significant difference was found between the two examiners for any implant sites. The result of the examination table was larger than that of the software for the shell reference point (t-test, P<0.05), but no significant difference was found for the angle deviation (t-test, P>0.05). The 45 implants positions in the 12 guides for the in vivo study were examined using the examination table. The deviations at the shell reference points were (1.06±0.29) mm (0.42-1.75 mm), and at the implant tip were (1.12±0.48) mm (0.41-2.44 mm). The angle deviations were (1.42±0.70) degree (0.29-2.96 degree).

CONCLUSION

Deviation is unavoidable during the fabrication process of the guides. The examination table of the ODI system is a reliable and valid tool to measure the deviation during fabrication of the ODI guides. More studies should be designed to research the relationship between the fabrication deviation and the implant insertion deviation.

[Influence of implants prepared by selective laser melting on early bone healing]

OBJECTIVE

To evaluate the influence of the rough surface of dental implants prepared by selective laser melting (SLM) on early bone healing around titanium implants.

METHODS

A total of sixteen titanium implants were involved in our research, of which eight implants were prepared by SLM (TIXOS Cylindrical, Leader-Novaxa, Milan, Italy; 3.3 mm×10 mm, internal hex) and the other eight were sandblasted, large-grit and acid-etched (SLA) implants (IMPLUS Cylindrical, Leader-Novaxa, Milan, Italy; 3.3 mm×10 mm, internal hex). All of the dental implants were inserted into the healed extraction sockets of the mandible of two adult male Beagle dogs. Half of the dental implants were designed to be healed beneath the mucosa and the other half were intended to be healed transgingivally and were immediately loaded by acrylic resin bridge restoration. Three types of tetracycline fluorescent labels, namely calcein blue, alizarin complexone and calcein, were administered into the veins of the Beagle dogs 2, 4, and 8 weeks after implant placement respectively for fluorescent evaluation of newly formed bone peri-implant. Both Beagle dogs were euthanized 12 weeks after implant insertion and the mandible block specimens containing the titanium implants and surrounding bone and soft tissue of each dog were carefully sectioned and dissected. A total of 16 hard tissue slices were obtained and stained with toluidine blue for microscopic examination and histomorphometric measurements. Histological observation was made for each slice under light microscope and laser scanning confocal microscope (LSCM). Comparison on new bone formation around titanium implants of each group was made and mineral apposition rate (MAR) was calculated for each group.

RESULTS

Dental implants prepared by selective laser melting had achieved satisfying osseointegration to surrounding bone tissue after the healing period of 12 weeks. Newly formed bone tissue was observed creeping on the highly porous surface of the SLM implant and growing into the pores of surface structure. Higher MAR values were shown for SLM implants compared with SLA implants (P<0.01).

CONCLUSION

Dental implants prepared by selective laser melting could promote early bone healing and improve mineral apposition rate.

[Influence of the interforaminal arch form of edentulous mandibles on design of "All-on-4": preliminary research based on conebeam computed tomography]

OBJECTIVE

To classify the interforaminal arch form of edentulous mandibles by measuring the anterior-posterior distance (A-P distance) of implants planned to be inserted in "All-on-4" protocol using conebeam computed tomography (CBCT) data, and to investigate the influence of the arch form on the "All-on-4" distally tilted implants.

METHODS

Seventy-four CBCT images of edentulous mandibles were collected, including 35 males and 39 females respectively. "All-on-4"implant supported fixed prostheses were designed for these patients based on the CBCT data. The A-P distance was measured in the plane which crossed bilateral mental foramens and was parallel to the occlusal plane. The interforaminal arch form of edentulous mandibles were classified according to the A-P distance. The radian of the jaw arch 7.5 mm mesially to the mental foramen was measured bilaterally, and its correlation with the A-P distance was studied.

RESULTS

The average A-P distance of implant supported fixed prostheses planned in the interforaminal region was (8.5±1.5) mm (minimum 4.5 mm, maximum 11.8 mm). In the study, 12.2% of the subjects' mandibles were classified as square arch form with A-P distances ≤7 mm, 54.0% were classified as ovoid with A-P distances >7 mm and ≤9 mm, 33.8% were classified as tapered with A-P distances >9 mm. Bilaterally, 148 results of the radian of the jaw arch 7.5 mm mesially to the mental foramen were obtained, and the average radian was 15.9°±5.5° (minimum 5.6°, maximum 35.2°). The radian and the A-P distance showed a negative correlation with statistical significance.

CONCLUSION

In this research, the ovoid arch form was the most common type in edentulous mandibles, followed by tapered arch form. The square arch form showed the lowest percentage. As the arch form went squarer, the A-P distance became shorter, the radian of the jaw arch mesially to the mental foramen went greater, and the bone width that distally tilted implants need became bigger. The interforaminal arch form of the edentulous mandible should be analyzed before an implant supported fixed restoration is designed in the interforaminal region. The angle of inclination of distal implants should be reasonable. The bone width of the distal implant site must be adequate. The square arch form contributes negatively to the structure of implant supported fixed prostheses with distal cantilever design.

[Evaluation of production and clinical working time of computer-aided design/computer-aided manufacturing (CAD/CAM) custom trays for complete denture]

OBJECTIVE

To compare the technician fabrication time and clinical working time of custom trays fabricated using two different methods, the three-dimensional printing custom trays and the conventional custom trays, and to prove the feasibility of the computer-aided design/computer-aided manufacturing (CAD/CAM) custom trays in clinical use from the perspective of clinical time cost.

METHODS

Twenty edentulous patients were recruited into this study, which was prospective, single blind, randomized self-control clinical trials. Two custom trays were fabricated for each participant. One of the custom trays was fabricated using functional suitable denture (FSD) system through CAD/CAM process, and the other was manually fabricated using conventional methods. Then the final impressions were taken using both the custom trays, followed by utilizing the final impression to fabricate complete dentures respectively. The technician production time of the custom trays and the clinical working time of taking the final impression was recorded.

RESULTS

The average time spent on fabricating the three-dimensional printing custom trays using FSD system and fabricating the conventional custom trays manually were (28.6±2.9) min and (31.1±5.7) min, respectively. The average time spent on making the final impression with the three-dimensional printing custom trays using FSD system and the conventional custom trays fabricated manually were (23.4±11.5) min and (25.4±13.0) min, respectively. There was significant difference in the technician fabrication time and the clinical working time between the three-dimensional printing custom trays using FSD system and the conventional custom trays fabricated manually (P<0.05).

CONCLUSION

The average time spent on fabricating three-dimensional printing custom trays using FSD system and making the final impression with the trays are less than those of the conventional custom trays fabricated manually, which reveals that the FSD three-dimensional printing custom trays is less time-consuming both in the clinical and laboratory process than the conventional custom trays. In addition, when we manufacture custom trays by three-dimensional printing method, there is no need to pour preliminary cast after taking the primary impression, therefore, it can save the impression material and model material. As to completing denture restoration, manufacturing custom trays using FSD system is worth being popularized.

[Distribution and content of transforming growth factor-β1 and vascular endothelial growth factor in each layer of concentrated growth factors]

OBJECTIVE

To investigate the distribution and content of transforming growth factor-β1 (TGF-β1) and vascular endothelial growth factor (VEGF) in concentrated growth factors (CGF) gel, and to clarify the difference among different layers of CGF.

METHODS

Venous blood samples were collected from 6 healthy volunteers to prepare CGF. The distribution, integrated optical density (IOD) and average optical density (AOD) of TGF-β1 and VEGF in CGF gel and red blood cell (RBC) layer were measured using immunohistochemistry. The concentrations of TGF-β1 and VEGF in the supernatant serum at baseline and the CGF releasate after 1 day were evaluated with enzyme-linked immunosorbent assays.

RESULTS

Abundant TGF-β1 and VEGF were concentrated in CGF gel. However, only a little could be found in polykaryocytes and sporadic platelets in RBC layer. Platelets and leukocytes were concentrated in between the two layers with high expression of TGF-β1. The concentrations of TGF-β1 and VEGF in the CGF releasate(55 236.78±3 686.34), (610.99±148.81) ng/L were significantly higher than those in the supernatant serum (20 710.20±4 523.14), (335.20±51.69) ng/L (P<0.001).

CONCLUSION

CGF contains high quantities of TGF-β1 that can promote new bone formation and tissue healing. We suggest that CGF gel should be used right after being prepared. Supernatant serum and the area between CGF gel and RBC layer could also be mixed with bone substitute materials.

[Surveillance of filariasis in some vulnerable areas in Guangxi after filariasis elimination]

OBJECTIVE

To explore the measures for continuing surveillance of filariasis.

METHODS

Selecting some vulnerable spots for focal surveillance, double-slide biood sampling for microfilaria examination, dissecting vectors for detecting the mosquitoes infected with filarial larva, using IFAT for detecting antifilarial antibody.

RESULTS

27,938 persons were examined for microfilaria and 4,454 mosquitoes were dissected for filaria larva, all were negative. 3,606 serum samples were examined for antifilarial antibody average positive rate was 1.35%(0.39-4.97%).

CONCLUSION

The results of surveillance showed that the achievement of filariasis control in Guangxi after filariasis elimination is consolidated.