[Effect of disinfectant with benzethon chloramine and isopropanol as main active ingredients on the accuracy of dental impression].

OBJECTIVE: To assess the effect of disinfectant (Cavicide) with benzethon chloramine and isopropanol as main active ingredients disinfectant on dental impression accuracy. METHODS: The effect of Cavicide on three impression materials (alginate, polyether and vinylpolysiloxane) were assessed using a standard model. The standard model was digitized by an extraoral scanner (IScan D103i, Imetric). For each kind of impression materials, thirty impressions were taken following the manufactures' instruction in the same conditions. Subsequently, the impressions were randomly divided into three groups, with ten impressions in each group. After the impression taking was completed, the three groups underwent pure water rinse for 1 min (blank control, BC), 2% glutaraldehyde solution immersion disinfection for 30 min (glutaraldehyde, GD), and Cavicide solution spray disinfection for 5 min (Cavicide, CC), respectively. All the impressions were digitized by the extraoral scanner (IScan D103i, Imetric) after disinfection and exported to a dedicated three-dimensional analysis software (Geomagic Qualify 2014, Geomagic, USA). In the software, the digital models of the impressions were trimmed to teeth and then superimposed with the digitized standard model via best-fit alignment. Root mean square (RMS) was used to evaluate the deviations between the impression and the standard model. The deviation in the anterior and posterior regions was evaluated respectively. One-way ANOVA test and the LSD post-hoc test were used to compare the deviations between the three groups (P < 0.05). The color map of each superimposition was saved for visual analysis. RESULTS: For the polyether and vinylpolysiloxane materials, the difference between the three groups was not statistically significant (P=0.933, P=0.827). For the alginate material, the difference in posterior region between group GD and group BC, as well as group GD and group CC were statistically significant (GD vs. BC, P=0.001; GD vs. CC, P=0.002), while the difference between group BC and group CC was not statistically significant (P=0.854). The visual analysis showed an obvious deviation in the buccal-lingual direction in group GD. CONCLUSION: Disinfectant (Cavicide) with benzethon chloramine and isopropanol as main active ingredients using spray disinfection has no effect on the accuracy of the alginate, polyether and vinylpolysiloxane impressions.

[Digital workflow coupling conic retention for the immediate restoration of adjacent posterior implants].

OBJECTIVE: To evaluate the digital workflow coupling conic retention for the immediate restoration of adjacent posterior implants. METHODS: The patients with adjacent teeth missing in the posterior jaw seeking for implant restoration in the Department of Implantology, Peking University School and Hospital of Stomatology from March, 2017 to February, 2018 were recruited. After implant placement and commercial conic retention coping delivery, the patient had an intraoral scan for digital impression, and the computer-assisted design/computer-assisted manufacturing (CAD/CAM) technology was used for the fabrication of the immediate splinted prosthesis, which was made of polymethyl methacrylate (PMMA) and loaded immediately after delivery. Six months later, all the temporary prostheses were replaced by the permanent ones made of monolithic zirconia with CAD/CAM technology as well. The parallel periapical films were taken for the temporary and permanent prostheses post-delivery. The clinical effect of this workflow was evaluated by indices including the survival rates of implants and prostheses, the change of marginal bone level, and the implant-related and prosthesis-related complications; before the final restoration, the Visual Analogue Score (VAS) was used to evaluate the satisfaction of the patients. RESULTS: Ten patients (4 males and 6 females, 55.5 years old for average) were recruited. Totally 34 implants were placed; 14 prostheses were fabricated, temporary and permanent, respectively. After an observation period from 4 to 14 months, the survival rate for implants and prostheses were both 100%; the marginal bone level of the implants were (1.06±0.97) mm and (0.96±0.82) mm, immediate post-operation and 6 months later, respectively. The difference was not statistically significant (P>0.05). Neither implant- nor prostheses- related complications were observed. And the VAS of the patients' satisfaction was 87.2. CONCLUSION: For the adjacent posterior implants, the immediate prostheses manufactured by digital workflow, coupling conic retention, were clinically feasible and patient-satisfactory.

[Validation of the digital integration technology for evaluating the nasolabial morphology variation after the cross-arch fixed restoration of maxillary implant-supported prostheses].

OBJECTIVE: To explore the applicability of integration between three-dimensional (3D) facial and dental data to evaluate the nasolabial morphology variation before and after the cross-arch fixed restoration of the maxillary implant-supported prostheses. METHODS: Twelve patients (4 women and 8 men), mean age (54.82±5.50) years (from 45 to 62 years) referred to the Department of Oral Implan-tology, Peking University School and Hospital of Stomatology, were selected and diagnosed with edentulous maxilla. For all the patients, 4 to 6 implants were inserted into the maxilla. Six months later, the final cross-arch fixed prostheses were delivered. The 3D facial images were collected before and after the final restoration. The 3D data of prostheses were also captured. All the 3D data were registered and measured in the same coordinate system. Then the displacement of all the landmarks [cheilion left (CHL), cheilion right (CHR), crista philtri left (CPHL), crista philtri right (CPHR), labrale supe-rius (LS), subnasale (SN), stomion (STO), upper incisor (UI), upper flange border of the prostheses (F-point, F)], and the variation of the distances between these landmarks (SN-LS, CPHR-CPHL, CHR-CHL, LS-STO) were analyzed and compared. RESULTS: The consistency test among three measurements of the length of F-SN indicated that the integration method of the dental prostheses and soft tissue had the good repetitiveness, ICC=0.983 (95%CI: 0.957-0.995). After wearing the final cross-arch maxillary implant-supported prostheses, all the landmarks on the soft tissue moved forward. The nasal base area changed minimally, and the shift of SN in the sagittal direction was only (0.61±0.44) mm. But the sagittal shift of LS was (3.12±1.38) mm. In the vertical direction, SN, LS, CPHL, and CPHR moved upward. But STO, CHL, and CHR moved downward a little. Except for the slight decrease of the length of philtrum (SN-LS), the length of CHL-CHR, CPHL-CPHR, and the height of upper lip were increased together (P < 0.01). In the direction of Z axis, the strong correlations were found not only between the movements of SN and F (r=0.904 3) but also between the movements of LS and UI (r=0.958 4). CONCLUSION: The integration method of 3D facial and dental data showed good repetitiveness. And the strong correlations between the landmarks of prostheses and nasolabial soft tissue in the sagittal direction were found by this new method.

[Effects of CAD/CAM titanium alloy surface treatment and resin luting on shear bond strength and durability of composite resin].

OBJECTIVE: To assess the effects of two surface treatments (sandblasting, SB; microarc-oxidation, MAO) and resin luting on shear bond strength and durability of titanium alloy and composite-resin. METHODS: Eighty cylindrical titanium alloy specimens with a diameter of 10 mm and a height of 8 mm were fabricated by CAD/CAM technique. It was divided into two groups according to the surface treatment methods: sandblasting with Al2O3 particles on the surface of SB specimens; porous ceramic film structure could be formed on the surface of MAO specimens after surface treatment. Each group was classified into SB-resin luting-N group (not used), SB-resin luting-Y group (used), MAO-resin luting-N group (not used), MAO-resin luting-Y group (used) depending on whether or not resin luting was applied. Each specimen was bonded and cured with the Cemerage resin, and the shear bond strength after 0 and 5 000 thermocycling was tested. The results were statistically analyzed. The surface morphology of titanium alloy specimens before and after the shear bond strength test was observed by scanning electron microscopy (SEM). RESULTS: The shear bond strength between titanium alloy and composite-resin was the highest in the SB combined with resin luting group after 0 thermocycling (16.2±1.8) MPa; was the lowest in MAO group after 5 000 thermocycling (8.9±1.5) MPa. The shear bond strength of SB and MAO surface treatment methods combined without resin luting group after 5 000 thermocycling were (10.7±2.2) MPa and (8.9±1.5) MPa, which were statistically lower than those in the thermocycling 0 (P=0.000 and P=0.001). The shear bond strength of SB and MAO surface treatment methods combined with resin luting group after 5 000 thermocycling were (15.5±2.1) MPa and (11.7±1.3) MPa, respectively, which were lower than those in the thermocycling 0 group, but there was no statistical significance (P=0.087 and P=0.234). CONCLUSION: Both the surface treatment methods of SB and MAO combined with resin luting can improve the shear bond strength and durability of titanium alloy and composite-resin. The SB combined with resin luting is more significant. At present, the effect of SB is better than that of MAO due to the limitation of technical parameters of micro-arc oxidation.

[Application of spark erosion technology in manufacture of implant prosthesis].

OBJECTIVE: To evaluate the influence of the implant-supported porcelain bridges made from non-precious metals using spark erosion techniques, and to discuss the feasibility and details of making the implant restoration by spark erosion technique. METHODS: The study included 12 patients (9 males and 3 females) with 92 units implant-supported non-precious porcelain bridge from Sep. 2011 to Feb. 2013. All the patients received implant treatment in Department of Oral Implantology, Peking University School and Hospital of Stomatology. The total of 52 implants, were from Nobel Biocare implant system, Camlog implant system and Ankylos implant system. The implant analogs were connected in sequence with a copper wire to guarantee conductivity. The implant electrodes represented one electrode and the superstructure the other. During spark-erosion machining, the cast holding the implant electrodes and the prosthetic framework were moved toward one another, causing an electrical erosion of the protruding elements. RESULTS: After the spark-erosion machining, the minimum gap between the framework and abutment was 0.21 mm, which was two units bridge. The maximum was 2.59 mm, which was 11 units bridge with 6 implants. The average gap was 0.68 mm. After the spark-erosion machining, the bridge fitted well with the passive position stability. CONCLUSION: The method of making implant-supported non-precious porcelain bridge reduces costs on patients. Spark erosion has the potential to provide implant framework with an excellent fit. The patients are satisfied with the clinical results.

[A follow-up study of the severe occlusal surface wear of implant-supported full-arch prostheses].

Objective: To evaluate the severe occlusal surface wear of implant-supported full-arch prostheses, and to explore the risk factors affecting the severe occlusal surface wear of implant-supported full-arch prostheses. Methods: Five hundred and thirty-five patients who received implant-supported fixed complete dental prostheses or implant-overdentures and completed at least one follow-up 3 months after the delivery of definitive prostheses were enrolled from October 1994 to October 2021 in this retrospective cohort study. The information on demographics, implants, definitive prostheses, and related outcomes was collected. Cox proportional hazard regression model was adopted to analyze the risk factors of the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Univariate analysis was performed on the factors that may affect the severe wear of occlusal surfaces, and the parameters of P<0.10 in univariate analysis were included in multivariate analysis to explore the risk factors affecting the severe wear of occlusal surfaces in implant-supported full-arch prostheses. Results: Severe wear of the posterior occlusal surfaces was detected in 114 prostheses with a duration of 61.4 (33.3, 89.4) months. 13 cases occurred≤2 years after the delivery of definitive prostheses, 44 cases>2 years and≤5 years, 44 cases>5 years and≤10 years, and the other 13 cases>10 years. There was no significant difference in the average time of severe occlusal surface wear between implant-supported fixed complete dental prostheses and implant-overdentures in the maxilla (Z=-1.03, P=0.303). However, in the mandible, it was 48.2 (31.2, 80.2) and 79.2 (51.3, 119.1) months respectively, which was statistically significant (Z=-2.93, P=0.003). Cox proportional hazard regression model showed opposed fixed dentition, bruxism, and posterior resin occlusal surfaces were risk factors (P<0.05) affecting the severe wear of the occlusal surfaces. Conclusions: Severe occlusal surface wear was clinically common with the prolonged application of implant-supported full-arch prostheses. Prostheses opposed to fixed dentition, in patients with bruxism, and made of posterior resin materials were at higher risk of severe occlusal surface wear on the posterior artificial teeth. Regular follow-up, patients' behavior guidance, and clinicians' appropriate intervention were necessary to manage this complication.

[Immediate rehabilitation of edentulous mandibles with implant-supported full-arch prostheses by intra-oral welding technique: a two-year follow-up].

Objective: To evaluate the 2-year clinical outcome of immediate loading implant-supported fixed full-arch prostheses in mandibles using intra-oral welding technique and to discuss the characteristics of the technique. Methods: Totally 15 patients (4 males and 11 females) who treated with immediate rehabilitation of edentulous mandibles with implant-supported full-arch prostheses from July 2015 to February 2019 in Department of Implantology, Peking University School and Hospital of Stomatology were included in the present study. The patients' average age was 64.2±9.3 years. In each case, 4 implants were placed in the mandible area, a titanium bar was connected with each of the implants by using intra-oral welding technique as the Ti-metal framework of the prostheses. Pre-fabricated abutment-level fixed prostheses were delivered immediately after the surgery. A total of 60 implants, 15 mandibles were treated. Biological and mechanical complications, hygiene of the tissue-contacted surface of the restoration and patients' satisfactory grade were recorded. The radiological fitness of welded frameworks to abutments, survival rate of implants and marginal bone loss were calculated and analyzed. The observation period of the study was 24-55 months, with an average of 34.9 months. Results: All of the 15 cases of welded bar-abutment frameworks were fixed on implants with well passive fitness in clinical and radiological level. However, 2 of the 60 implants were failed by loss of osseointegration, and the result of implant survival rate of 96.7% in 2 years. The average marginal bone loss was (0.7±0.2) mm. The average bleeding index of the 58 implants remained was under 3 without clinical signs of gingival swelling, tenderness or fistula. No mechanical complications, such as break or distortion of the implants, occurred. Fracture of artificial teeth and complex resin area happened in 6 of the 15 prostheses. The average debris index was 3.4±0.4 and the hygiene of the tissue-contact areas was under satisfactory condition. Conclusions: Using the intra-oral welding technique to achieve a rigid splint of implants, the clinical outcome of the newly performed technique was predictable in early stage. The frame structure remained stable to avoiding the occurrence of mechanical complications. The provisional restoration could be expected to provide long functional period. Long term result of the treatment were needed for further observation.

[Implant-supported fixed full-arch prostheses on oral health-related quality of life and denture satisfaction].

Objective: To assess the longitudinal changes in oral health-related quality of life (OHRQoL) and the denture satisfaction of immediate rehabilitation by implant-supported full-arch prostheses in patients of the edentulous and potential edentulous jaws. Methods: Patients in the Department of Implantology, Peking University School and Hospital of Stomatology from April 2008 to November 2020 were enrolled in the study. The treatment group (TG) consisted of 73 patients who had been treated with immediate rehabilitation by using implant-supported full-arch prostheses while the control group (CG) consisted of 31 patients who would be treated with immediate rehabilitation of implant-supported full-arch prostheses. The mean age of the patients in the treatment group was (57.5±11.1) years (ranged 31-79) and the average follow-up duration was 5.5±2.9 years (ranged 1-12). The OHRQL ratings were collected using oral health impact profile-20 (OHIP-20) and the visual analogue scales (VAS) was used to assess the denture satisfaction including stability, aesthetics, mastication, ease of cleaning, speaking and general satisfaction. Independent t-test, Mann-Whitney U-test and locally weighted scatterplot smoothing were applied for data analysis. Results: The cumulative survival rate (CSR) of the implants was 97.6% (450/461). The CSR of the prostheses was 93.3% (98/105). The average peri-implant marginal bone loss (MBL) was (0.8±0.4) mm and (1.2±0.6) mm after 1 and 5 years, respectively. The mean OHIP-20 total scores of TG and CG were 5(7) and 32.9±12.6, respectively, which had statistical difference between the two groups (P<0.001). The general satisfaction in the TG was 95.0(10.0), while the higher scores were for chewing [100.0(7.5)] stability [100.0(10.0)] and esthetics [100.0(10.0)] and the lower scores were for ease of cleaning [85.0(25.0)] and speaking ability [100.0(12.5)]. With prolonged follow-up, the total OHIP-20 score decreased significantly at first and then remained stable with minor fluctuations. Conclusions: Based on the present study, immediate rehabilitation with implant-supported full-arch prostheses was a feasible treatment program that had a long-term positive impact on OHRQoL, provided strong psychological and sociological support to the patients and restored the chewing and speech functions effectively.

[Plaque accumulation at the fitting surface and cleaning status in patients with full-arch implant-supported fixed prostheses: a cross sectional study].

Objective: To observe the plaque accumulation at the fitting surface and oral hygiene status in patients with full-arch implant-supported fixed prostheses, and explore the possible influencing factors. Methods: Twenty-eight patients [17 males and 11 females, (63.0± 10.8) years old] with 40 full-arch implant-supported fixed prostheses (18 maxillary and 22 mandibular) were collected from January 2012 to September 2020 in Department of Implantology, Peking University School and Hospital of Stomatology. Plaque accumulation at the fitting surfaces were evaluated during the follow-up visit after 6 months following definitive prostheses delivery, by analyzing the digital photographs recorded by ImageJ. Meanwhile, the cleanliness of the fitting surface of prostheses and oral hygiene status were recorded. The oral hygiene habits and the patients' satisfaction with the prostheses were investigated by questionnaire, and the difference of plaque accumulation between different cleaning habits of dentures were compared. Results: The debris index of the fitting surface of the 40 full-arch implant-supported fixed prostheses were 3.28±0.75, and the percentage of area covered with plaque was (51.6±19.0)%. The debris index and plaque accumulation of the mandibular prostheses were significantly higher than that of the maxillary prostheses (P<0.05). In most mandibular prostheses (16/22), calculus was attached to the lingual side of the anterior tooth area. The reserved cleaning space of the restoration showed more plaque accumulation than in other parts. There was no significant difference in the percentage of area covered with plaque between groups with different cleaning habits. The satisfaction survey results indicated the "clean" project had a lowest score. Conclusions: The cleanliness of patients with full-arch implant-supported fixed prostheses was poor, and the hygiene status of the mandibular prostheses was worse than that of maxillary, especially in the anterior tooth area of mandibular prostheses. The influence of different cleaning habits on plaque accumulation was not observed.

[Immediate rehabilitation of the edentulous and potential edentulous jaws with implant-supported full-arch prostheses: a retrospective analysis of 225 cases].

Objective: To evaluate the outcomes of immediate rehabilitation of the edentulous and potential edentulous jaws with implant-supported full-arch prostheses and analyse the risk factors of the complications. Methods: This retrospective study included 273 patients treated with immediate rehabilitation of the edentulous and potential edentulous jaws with implant-supported full-arch prostheses from April 2008 to December 2018 in Department of Implantology, Peking University School and Hospital of Stomatology. The patients' sex, age, place of residence, jaw position, opposing dentition, number of implants, diameter and length of implants, abutment height and abutment angle were recorded. The survival rate of implants and marginal bone loss were calculated and analyzed. Cox proportional hazards ratio model was adopted to analyze the potential risk factors of prosthetic complications. Results: A total of 225 patients (288 jaws) and 1 260 implants were included, with 126 males and 99 females, aged (57.3±11.0) years, with a following time of (5.04±3.08) years. The 1-year cumulative survival rate of implants was 98.0% (1 235/1 260). Forty-eight implants were lost during the follow-up, with 39 implants in the maxillae and 9 implants in the mandible. The risk of implant failure of the maxillae ï¼»7.2% （39/541）］ is significantly higher than that of the mandible ï¼»1.3% （9/719）］ (P<0.01). Average marginal bone loss at 1 and 5 years was (0.7±0.2） mm and （1.1±0.3） mm. One hundred and twenty patients experienced prosthetic complications including screw/abutment loosening (44 cases), screw/abutment fracture (2 cases) and artificial tooth/denture base fracture (99 cases). The possibility of immediate prosthesis fracture within 6-8 months was high but declined over the following years with the final prosthesis delivered. Cox regression analysis showed that the use of 17° abutments in the anterior region was significantly related to the prosthetic complications （hazard ratio=1.797, P=0.002）. Conclusions: Immediate rehabilitation of the edentulous jaws with implant-supported full-arch prostheses can be a predictable technique. The immediate prosthetic mechanical complication prevalence was high. The use of 17° abutments in the anterior region may increase the risk of screw/abutment loosening. It is necessary to review in time.

[Application of and progress in computer aided design and computer aided manufacture materials by chairside digital workflow in implant prosthodontics].

With the emergence and development of new dental materials, chairside computer aided design/computer aided manufacture (CAD/CAM) materials, as an important part of digital technology, is gaining increasing progress to meet the needs of implant restorations and digital processing technology for the mechanical properties, chemical stability, biocompatibility and processing properties. A large number of in-vitro experiments and clinical studies have been reported on various materials, such as polycrystalline ceramic, glass ceramic and indirect composite. The purpose of this article is to review the performance, the clinical indications and applications of the CAD/CAM materials for chairside digital workflow in implant prosthodontics.

[Quantitative three-dimensional methodology based on intraoral scan to assess the soft tissue contour alterations following single immediate implant and immediate provisionalization in maxillary central incisor: a 1-year prospective study].

Objective: To establish a quantitative three-dimensional method based on intraoral scan and apply it to evaluation of the facial soft tissue contour alterations following single immediate implant and immediate provisionalization (IIPP) in central incisor via intraoral scanning. Methods: This study was a prospective clinical study. The trial was conducted at Department of Implantology, Peking University School and Hospital of Stomatology, from January 2016 to September 2017. Twenty-nine eligible consecutive patients (15 women, 14 men) with a mean age of (34.3±12.0) were included and received immediate replacement of the failure maxillary single central incisor. A screw-retained immediate restoration was delivered for each patient. At 6-month follow-up, impression was taken and a screw-retained permanent restoration was performed for each patient. The anterior maxillary region was scanned by an intraoral scanning system at pre-surgery and 1-year follow-up. The Standard Tessellation Language (STL) files were output to a dedicated software and superimposed. Mid-facial recession and gingival zenith symmetry at 1-year follow-up were measured in the digital models. Three-dimensional configurations of the contour change volume were calculated and reconstructed for visual analysis. Furthermore, the following parameters were used to analyze the reconstructed volume: mean contour change in thickness (△d), mesio-distal width (D(W)), coronal-apical height (D(H)), contour change at 0, 1, 2, 3, 4, 5 mm apical to the free gingival margin on the implant site. Results: Twenty-seven out of twenty-nine enrolled patients were finally available for analysis. At 1-year follow-up, the mid-facial mucosa level at implant site was (0.23±0.39) mm apical to the gingival zenith of the contralateral tooth. In general, a contour collapse was found in every patient. △d, D(W) and D(H) of the collapsed volume were (0.62±0.22), (11.03±1.74) and (6.82±1.52) mm, respectively. Contour change at 0, 1, 2, 3, 4, 5 mm apical to the free gingival margin on the implant site were (0.54±0.48), (0.87±0.62), (1.03±0.46), (0.96±0.52), (0.90±0.52), (0.89±0.57) mm. Conclusions: The described quantitative measurement based on intraoral scan can be an effective method for assessment of soft tissue contour changes. At 1 year following single IIPP treatment in maxillary incisor, free gingival margin is stable, with only mild recession. The mean level of the facial soft tissue contour collapse is 0.62 mm.

[Complications of implant-supported full-arch immediate prosthesis: a retrospective analysis of 114 cases].

Objective: To evaluate the feasibility of long-term function of implant-supported full-arch immediate prosthesis via assessing the complications and risk factors. Methods: This historical cohort study included patients treated with implant-supported full-arch restoration under immediate loading protocol between April, 2008 to June, 2016 and wearing the immediate prosthesis for more than 6 months. Medical charts were reviewed for patients' general information, implant information, prosthetic information and details of prosthetic complications. COX proportional hazards ratio model was adopted to analyze the potential risk factors for prosthesis fracture. Results: A total of 114 patients with a mean age of (56.7±10.2) years old and 144 prostheses were included. The median wearing time of immediate prosthesis was 17.6 months. Sixty-two (54%) patients experienced prosthetic complication, 30 of them suffered more than once. Artificial teeth fractures were more common in anterior region while resin base fractured more often in the posterior region. The possibility of immediate prosthesis fracture in the first year was high but declined over the following years. COX regression analysis showed that fibre-reinforcement (HR=0.486, P=0.017) and rigid opposing dentition (HR=2.272, P=0.016) were significantly related to the prosthesis fracture. Conclusions: Long-term function of implant-supported full-arch immediate prosthesis renders a high prosthetic complication prevalence, featuring the prosthesis fracture as the most common complication and the first year of highest fracture probability. Fibre-reinforced acrylic immediate prosthesis may function well in cases with a removable denture restored opposing jaw.

[Systematic review and meta-analysis on the effect of implant supported overdentures on the oral health related quality of life of edentulous patients].

Objective: To evaluate the effect of implant related treatment on the oral health related quality of life (OHRQoL) of edentulous patients. Methods: The CNKI, Wanfang database and Medline, EMBASE, Cochrane Library databases that include randomized clinical trials comparing implant supported overdentures with conventional complete denture for edentulous patients were retrived. Nine studies involving 769 cases were included and meta-analysis was conducted. Results: The standardized mean difference (SMD) of oral health impact profile (OHIP) score was 1.63 (95%CI: 1.25-2.02) and improved after implant related treatment, which was significantly better than the conventional complete denture (0.87, 95% CI: 0.54-1.20). Conclusions: Implant supported overdentures improved patient's OHRQoL and showed better performance compared to the overdentures complete dentures.

[Lateral cephalometric analysis of patients with maxillary alveolar protrusion and advanced periodontitis treated with immediate implants and cross-arch fixed prostheses].

Objective: To investigate the changes of the lateral cephelometric landmarks of soft tissue and hard tissue of patients with maxillary alveolar protrusion and advanced periodontitis treated with immediate implants and cross-arch fixed prostheses. Methods: From January 2013 to October 2016, consecutive patients with advanced periodontitis and maxillary alveolar protrusion in need of immediate implants and cross-arch fixed prostheses were included in this study. All the patients were treated with provisional cross-arch fixed prostheses supported with 4 to 6 immediate implants after extraction of all the residual teeth and reduction of excessive alveolar bone. After 6 months, a final cross-arch fixed prosthesis was delivered. The lateral cephalometric landmarks of soft tissue and hard tissue at the time of pre-operation and final prosthesis delivery were analyzed. The change of patients' facial aesthetics was assessed using visual analogue scale (VAS). Results: Ten patients were included in the study. All the patients underwent full arch rehabilitation of both jaws supported by a total of 89 dental implants. In the maxillae, the average number of inserted implants were 4.5. The mean height of alveolar bone reduction was (6.3±1.8) mm. Both the distance of U1-NA (the upper incisor to nasion-A point line) and U1-PP (the upper incisor to palatal plane) were significantly reduced by (5.5±2.7) mm and (1.6±1.2) mm, respectively. The angle of U1-SN (between upper incisor to sella-nasion line) was reduced by 9.6°±8.1°palatally. The nasolabial angles were significantly increased by 10.5°±6.4°. Both the patients and dentists considered that the facial aesthetics was improved greatly after the treatment. Conclusions: With the reduction of excessive alveolar bone and the realignment of artificial teeth, the treatment of immediate implants and cross-arch fixed prostheses could improve the facial aesthetics of the patients with advanced periodontitis and maxillary alveolar protrusion.

[A pilot clinical study of immediate provisionalization with a chairside computer aided design and computer aided manufacture monolithic crown for single tooth immediate implant placement].

Objective: To evaluate the primary clinical outcomes of immediate provisionalization with a monolithic crown utilizing a novel chairside computer aided design and computer aided manufacture (CAD/CAM) workflow for single tooth immediate implant placement. Methods: This pilot study was a prospective within-subjects design. Thirteen consecutive patients were included and diagnosed with untreatable single incisor or premolar with fine general and local anatomical conditions. The trial was conducted at Department of Implantology, Peking University School and Hospital of Stomatology, Beijing, between January 2016 and June 2016. The teeth were extracted atraumatically and implants were immediately placed in the fresh sockets. Two screw-retained interim crowns were fabricated for the same site utilizing different workflows, a monolithic lithium disilicate (LS2) crown produced by CEREC (Sirona, Germany) chairside CAD/CAM system (CER group) and a manually fabricated resin crown utilizing conventional workflow (CONV group) respectively. The patients were blinded to the group allocation of the two interim crowns. After the clinical try-in for both crowns in a randomized sequence, the patients' level of satisfaction was assessed with a virtual analogue scale (VAS) questionnaire. The restorations chosen by patients themselves were seated in the implants by one experienced prosthodontist. The accuracy, aesthetic effect and clinical time consumption of both groups were compared. Statistical analyses were performed with the Wilcoxon signed rank test. Results: All patients were treated with atraumatic tooth extraction, immediate implant placement using flapless surgery and immediate provisionalization in a single visit. The interim crowns of both groups could be fitted with or without slight adjustments. For each patient, the interim crown of CER group was chosen to be seated with a relatively higher VAS result. The white esthetic score (WES) results demonstrated no statistically significant difference between CER group (7.5±1.1) and CONV group (7.9±0.9) (P>0.05). The mean total work time was significantly different resulting in (131.9±5.0) min for CER group and (205.2±6.3) min(P<0.05). The major difference lied in the laboratory work time, resulting in (113.5±6.3) min for CER group which was significantly shorter than (185.6±6.6) min for CONV group. As for impression taking time, the CER group (7.5±0.8) min was significantly shorter than CONV group (11.7± 1.1) min (P<0.05). However, analysis for clinical adjustment time showed a significantly longer time for CER group [(11.0±2.1) min vs (8.0±2.8) min, P<0.05]. After 3-6 months of observation, the overall survival rate was 100%. Screw loosening occurred in 4 patients and was tightened again. No other major complication soccurred. Conclusions: The full digital workflow utilizing CEREC chairside CAD/CAM system to fabricate interim crowns after immediate implant placement in one single visit was feasible. It was more time-efficient and could effectively shorten the laboratory work time compared to the conventional workflow. Patients demonstrated high satisfaction and there was no statistical difference in WES results compared to the conventional workflow. Favorable clinical outcomes were gained in this short-term follow-up study.

[Cone-beam CT evaluation of alveolar ridge modification subject to immediate implant with immediate loading and delayed loading].

Objective: To assess and compare the radiographic outcomes of immediate implant placement with two different loading timing. Methods: The involved cases were collected from Department of Implantology, Peking University School and Hospital of Stomatology. Patients recieved immediate implant placement during 2010 Aug to 2012 Dec. The cases admitted delayed restoration program were assigned to Group Ⅰ(18 patients with 21 implants), the cases admitted immediate restoration program were assigned to Group Ⅱ (16 patients with 22 implants). Cone-beam CT(CBCT) was taken on the day after surgery and 6 months later. The thickness of the alveolar and the vertical alteration of marginal bone level were measured using the computer software subject to the CBCT. Wound closure was performed by single sutures in Group Ⅰ. Provisional crown was delivered on the same day of implant insertion or the day after for Group Ⅱ. Comparisons between baseline data and data from 6-month follow-up in both groups were conducted using paired t test(α=0.05). Results: The success rates of two groups were both 100%. The thickness got alteration after 6 months. The largest alteration position was at the 6 mm apical to the implant platform in Group Ⅰ, which was (-0.75±1.31) mm. In Group Ⅱ for each platform got similar alterations as -0.3 mm. There was no significant differences. Vertical alteration in two Groups showed significant difference, with (-0.73±1.88) mm(Group Ⅰ) and (0.39±1.37) mm(Group Ⅱ) respectively. Conclusions: Immediate restoration of dental implants which are placed in fresh extraction sockets has more advantages than delayed restoration protocol, for it shortens the course of treatment and preserves the alveolar bone.

[All-on-4 occlusion study: using T-Scan â ¢ occlusal analysis system].

OBJECTIVE: To investigate the occlusal force distribution and the characteristics of the occlusion time of patients with All-on-4 rehabilitation at different occlusion position using T-Scan Ⅲ occlusal analysis system. METHODS: Thirteen volunteers with All-on-4 rehabilitation were included in this study. T-Scan Ⅲ occlusal analysis system was used to measure the occlusal force distribution and the time character of the patients at intercuspal position, protrusive position, and lateral excursive position. RESULTS: Maximum intercuspation: the left and right premolars took most of the occlusal force, namely (17.3±3.1)%, (15.8 ± 4.6)%, (15.5 ± 2.2)% and (15.2 ± 5.5)% (24, 25, 14, 15), the implants areas including the premolar and anterior teeth took (64.0±6.7)%, (19.2±8.0)% of occlusal force. The left and right sides took the respective percentages of (50.5±6.1)%, (49.5±6.1)%, and there was no difference. Protrusion position: the region (11, 12, 21, 22) commitment to take the percentage of (90.4±27.7)%. Occlusion time: 0.18(0.11, 0.26) s, disclusion time: 0.52 (0.35, 1.14) s . At the left and right lateral position, 8 patients were single teeth-supported occlusion, 5 patients were group fuctional occlusion, the average occlusion time was 0.20(0.13, 0.34) s, and DT was 1.07 (0.58, 1.46) s. CONCLUSIONS: At maximum intercuspation: the implants areas including the premolar and anterior teeth were the occlusal force centers; the force concentrated in the area (11, 12, 21, 22) at the protrusion position. The lateral occlusal pattern shows multiformity.