OBJECTIVE: To verify the consistency between the digital manufacturing simple intraoral Gothic arch-tracing device and the traditional intraoral Gothic arch-tracing device in determining the centric relation of complete dentures restoration. METHODS: Ten outpatients with edentulous jaws were selec-ted, and the centric relation of the patients was determined by digital manufacturing of simple intraoral Gothic arch-tracing device (T1) and traditional intraoral Gothic arch-tracing device (T2); the difference of clinical operation time between the two methods was recorded; the upper and lower edentulous jaw plaster models were scanned with two kinds of centric relation, the Standard Triangle Language (STL) files imported into Geomagic studio software to apply the best fitting of multiple points of the both upper jaw models, the fitted STL files imported into the 3 shape viewer software, and the maximum position deviations of the vertical, labial (buccal) and lingual directions of the mandibular midline area and molar areas in T1 and T2 groups measured. During the clinical complete dentures try-in, we observed whether there was midline deviation in the mouth of T1 group and T2 group, and whether the occlusion of posterior teeth was stable or not. RESULTS: The mean time spent on determining the centric relation of T1 and T2 groups was (41.90±2.64) min, (57.50±2.37) min respectively. Paired t test was conducted in the two groups, P < 0.01 with significant statistical difference; The mean maximum position deviation between T1 group and T2 group of the midline mandibular region in labial lingual direction was (0.32±0.14) mm, that was (0.40±0.23) mm in vertical direction; the mean maximum position deviation of molar area in buccal lingual direction was (0.35±0.23) mm and that was (0.33±0.20) mm in vertical direction. In the vertical and horizontal directions, the maximum position deviation of mandibles between group T1 and group T2 was controlled within 0.5 mm. In the process of clinical complete dentures try-in, there was no deviation from the center line of dentures. There was not warping, swinging and other poor stability phenomena in T1 and T2 groups. CONCLUSION The digital manufacturing of simple intraoral Gothic arch-tracing device can be used to determine the centric relation of complete dentures, which can not only save time of clinical operation, but also ensure the accuracy of the centric relation.
Humans ; Centric Relation ; Jaw Relation Record/methods* ; Denture, Complete ; Mouth, Edentulous ; Jaw, Edentulous

Aged ; Alveolar Bone Loss ; pathology ; Alveolar Process ; pathology ; Dental Care for Aged ; Dental Implantation, Endosseous ; Dental Occlusion ; Dental Restoration, Permanent ; Humans ; Jaw, Edentulous, Partially ; pathology ; Mouth, Edentulous ; pathology ; Tooth Loss ; pathology

OBJECTIVETo evaluate the outcomes of immediate post-extraction implant and immediate function according to All-on-4 immediate concept in edentulous patients.

METHODSThe study included 46 patients with hopeless teeth. A total of 254 implants were immediately inserted after extraction and 56 fixed complete-arch all-acrylic prostheses finished and functioned on the day of extraction from June 2008 to March 2012 in Peking University School of Stomatology. At time of abutments connection, a panoramic radiograph was taken, and radiographic assessment of the marginal bone level was performed in every 6 months. Marginal bone level, integrity of the restoration, survival of the implants and degree of satisfaction of the patients were evaluated.

RESULTSA total of 254 implants were immediate loading. Thirteen implants were lost 6 - 8 weeks after immediate loading and the survival rate of 94.9% (241/254). The marginal bone absorption was (0.7 ± 0.3) mm on average. All patients were satisfied with the clinical results.

CONCLUSIONSImmediate post-extraction implant and immediate function technique can be a predictable technique. Further study is needed to determine the long-term results of the technology.

Dental Implants ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure ; Humans ; Jaw, Edentulous ; Mouth, Edentulous

When design an implant restoration for edentulous patients, many doctors ignore the sufficiency of the interarch distance (vertical distance) or horizontal distance of the patient to accommodate the superstructure and restoration before designing the implant plan. However, the connotation of measuring the interarch distance or horizontal distance has not been clarified in clinical practice. It is often based on visual estimation after operation, and the decision-making path of implant restoration is inverted, resulting in many mistakes regarding the restoration after implantation. The main reason is the lack of standardized paths and practical methods to use before surgery. This article recommended initially establishing a maxillo-mandibular relationship based on natural teeth, old dentures, or new ones and then using the height and horizontal distance or angle of the target restorative space, which was easier to grasp as the measured index. The minimum vertical distance (including the height of the gingival surface and the bone surface) and the horizontal distance (or the angle from the bone or gingival surface to the proposed occlusal plane) should be measured before operation. A decision tree of edentulous jaw restoration guided by the values of the repair space was established based on the measured values. This article clarified the measuring points and planes and thus provided a quantitative relationship basis for the design of implant restoration.
Dental Implantation, Endosseous ; Dental Implants ; Dental Prosthesis, Implant-Supported ; Humans ; Jaw, Edentulous ; Mandible ; Mouth, Edentulous

OBJECTIVE: To compare the operation complexity and accuracy of traditional splint impression technique and impression technique with prefabricated rigid connecting bar system for full-arch implants-supported fixed protheses in vitro. METHODS: Standard mandibular edentulous model with six implant analogs was prepared. The implants were placed at the bone level and multiunit abutments screwed into the implants. Two impression techniques were performed: the traditional splint impression technique was used in the control group, and the rigid connecting bar system was used in the test group. In the control group, impression copings were screwed into the multiunit abutments and connected with autopolymerizing acrylic resin. Open tray impression was fabricated with custom tray and polyether. In the test group, cylinders were screwed into the multiunit abutments. Prefabricated rigid bars with suitable length were selected and connected to the cylinders with small amount of autopolymerizing acrylic resin, and open tray impression was obtained. Impression procedures were repeated 6 times in each group. The working time of the two impression methods were recorded and compared. Analogs were screws into the impressions and gypsum casts were poured. The gypsum casts and the standard model were transferred to stereolithography (STL) files with model scanner. Comparative analysis of the STL files of the gypsum casts and the standard model was carried out and the root mean square (RMS) error value of the gypsum casts of the control and test groups compared with the standard model was recorded. The trueness of the two impression techniques was compared. RESULTS: The work time in the test group was significantly lower than that in the control group and the difference was statistically significant [(984.5±63.3) s vs. (1 478.3±156.2) s, P < 0.05]. Compared with the standard model, the RMS error value of the implant abutments in the test group was (16.9±5.5) μm. The RMS value in the control group was (20.2±8.0) μm. The difference between the two groups was not significant (P>0.05). CONCLUSION The prefabricated rigid connecting bar can save the chair-side work time in implants immediate loading of edentulous jaw and simplify the impression process. The impression accuracy is not significantly different from the traditional impression technology. The impression technique with prefabricated rigid connecting bar system is worthy of clinical application.
Acrylic Resins ; Calcium Sulfate ; Dental Implants ; Dental Impression Materials ; Dental Impression Technique ; Humans ; Jaw, Edentulous ; Models, Dental ; Mouth, Edentulous

PURPOSE: The primary aims of this retrospective study were to compare subjective bone quality and bone quality based on the Hounsfield scale in different segments of the edentulous jaw, and to establish quantitative and objective assessment of the bone quality. MATERIALS AND METHODS: Twenty eight randomly selected cone-beam computed tomographic (CBCT) scans were analyzed. For evaluation one hundred and twelve edentulous areas were selected. Implant recipient sites were evaluated visually for Lekholm and Zarb classification. The same sites were subsequently evaluated digitally using the Hounsfield scale with Vimplant2.0(TM), and the results were correlated with visual classification. Data was subject for statistical analysis in order to determine correlation between recorded HU and the regions of the mouth with the Kruskal-Wallis test. RESULTS: The highest unit/mean density value (311 HU) was found in the anterior mandible, followed by 259 HU for the posterior mandible, 216 HU for the anterior maxilla, and 127 HU for the posterior maxilla. These results demonstrate a strong correlation for HU depending on the region of the mouth (p<0.001). The relationship between HU and type 4 bone was found to be significant (r=0.74). CONCLUSION: Knowledge of the Hounsfield value as a quantitative measurement of bone density can be helpful as a diagnostic tool by using CBMercuRay(TM) with Vimplant(TM) software.
Bone Density ; Cone-Beam Computed Tomography ; Jaw, Edentulous ; Mandible ; Maxilla ; Mouth ; Retrospective Studies

Conventional denture impression techniques have limitations for edentulous patients with severe alveolar bone resorption and can cause problems from excessive border extension. Especially when a patient has movable tissue it is difficult to make accurate impression, thus might interrupt stable seating of complete denture. Fabrication of complete denture using closed mouth technique for edentulous patient with severe ridge resorption is thought to provide better stability and retention. In this case, an 86-year-old patient had both edentulous jaws with epulis fissuratum on maxillary anterior ridge and severe mandibular ridge resorption. Thus, tentative vertical dimension was determined by using Centric tray and individual tray attached with gothic arch tracer was fabricated. Complete denture was fabricated using closed mouth technique and the patient was satisfied with better stability and retention of the complete denture.
Aged, 80 and over ; Bone Resorption ; Denture, Complete* ; Dentures ; Gingival Diseases ; Humans ; Jaw, Edentulous ; Mouth* ; Vertical Dimension

OBJECTIVES: This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator. METHODS: Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed. RESULTS: For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (P<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (P<0.05). CONCLUSIONS For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.
Humans ; Mouth, Edentulous ; Occlusal Adjustment ; Jaw Relation Record ; Dental Articulators ; Software

OBJECTIVETo reconstruct the centric relation of upper and lower edentulous dental models with two methods, to compare the reconstruction accuracy of the vertical and horizontal distance, and to provide some references to computer aided design and computer aided manufacture for complete denture.

METHODSDental models and rims made from five edentulous patients in clinical were obtained.Each model was stocked with 10 identical size positioning cylinders (20 cylinders on each pair models) on 5 side-surfaces of basement. Twelve center point pairs were paired between upper and lower models from 20 cylinder bottoms. The vertical and horizontal distances of 12 center point pairs were regarded as the evaluation items. Firstly, upper and lower models and rims were scanned separately. Then, models and rims (fixed in centric relation respectively with positioning articulator and rubber banding) were scanned.In software, all the data were registered to reconstruct centric relation based on common region. Digital models were measured with software tools, and real models were measured with a contact measurement arm. The differences of the homologous items between two methods were analyzed with paired-t test.

RESULTSThe vertical distance errors for dental articulator positioning method was (0.356 ± 0.200) mm and that of the rubber band method was (0.382 ± 0.299) mm, and paired-t test between the two methods showed no significant differences (P > 0.05). The horizontal errors were (0.010 ± 0.411) mm and (0.104 ± 0.476) mm, and paired-t test showed significant differences (P < 0.05).

CONCLUSIONSComparing with rubber band method, dental articulator positioning can significantly increases three-dimensional reconstruction accuracy of edentulous jaw gypsum models' horizontal relation.

Centric Relation ; Computer-Aided Design ; Dental Articulators ; Dental Models ; Denture, Complete ; Humans ; Image Processing, Computer-Assisted ; Jaw, Edentulous ; Mouth, Edentulous ; Software ; Tomography, X-Ray Computed

OBJECTIVETo evaluate the 10-year clinical results of implant prostheses in edentulous patients.

METHODSBetween August 1994 and November 2009, 762 implants were placed in 127 patients (162 jaws) with the mean age of (56.0 ± 10.9) years in Peking University, School and Hospital of Stomatology. Sinus lift, guide bone regeneration (GBR) and onlay graft were used according to the indications of bone defect types. Overdentures and fixed bridges were delivered.Overdentures were retained/supported by ball, magnet, telescopic crown or milled bar. Clinical evaluation included peri-implant soft tissue health status, prostheses functional status and complications.Radiographic evaluations were conducted at operation day, 3 months post-operatively, right after prostheses delivery, and annually afterwards. Clinical data were collected and analyzed.

RESULTSOf the 127 patients, 116 were edentulous mandible and 46 edentulous maxilla, with a mean follow-up period 109.2 months(45-228 months). Thirteen implants were lost and the 10-year implant cumulative survival rate was 97.8% and the prostheses success rate was 100.0%. The prevalence of peri-implantitis was 3.8% (29/762). Sixty-seven point nine percent of the patients underwent implant placement without bone graft.Sinus lift technique and guided bone regeneration technique were the most often used with 84.8% (39/46) in the upper jaws and 6.2% (10/162) in the total jaws respectively. Seventy-one percent of the cases(115/162) was overdentures. Telescopic, milled-bar, and magnetic retained/supported overdentures were the most commonly used with 34.8% (40/115) , 27.0% (31/115) , and 20.0% (23/115) respectively. The implant-supported fixed prostheses included adhesive retained fixed bridges and screw retained fixed bridges with the ratio of 19.1% and 80.9% respectively. The prevalence of 10-year post-prosthodontic complications was 53.5% (68 cases). The most common complications were prosthetic and uperstructure complications.

CONCLUSIONSThe 10-year implant-retained/supported prostheses was a successful modality in edentulous cases.Sinus lift technique and guided bone regeneration technique are the most commonly used techniques with predictable clinical results. Telescopic crowns milled bar and magnet with 4-6 implants retained/supported overdenture were the most often used retention systems and telescopic crown overdenture had more advantages in terms of long-term maintenance and satisfaction.

Crowns ; Dental Implants ; Dental Prosthesis Design ; Dental Prosthesis, Implant-Supported ; Denture, Overlay ; Humans ; Jaw, Edentulous ; Maxilla ; Mouth, Edentulous ; Peri-Implantitis ; Retrospective Studies