OBJECTIVES: This study aimed to evaluate the long-term clinical efficacy of simple taper retentive implants in the posterior dental area after immediate implantation for 5-7 years. METHODS: Selected from January 2015 to December 2017 in the Fourth Affiliated Hospital of Nanchang University dental clinic line tooth area immediately after the implant prosthesis, a total of 38 patients, 53 implants, were deep into (bone under 2 mm or higher) and the upper structure was repaired. In addition, after the completion of tracking observation of 60-90 months, the implant surrounding bone health was recorded and analyzed. RESULTS: After 5-7 years of follow-up, 1 of the 53 implants failed to fall out, and the implant retention rate was 98.1%. The amount of bone resorption in the proximal and distal margins 5-7 years after implant restoration was (0.16±0.94) mm and (-0.01±1.29) mm, respectively, and the difference in bone height between the proximal and distal margins of the implant and the immediate post-restoration period was not statistically significant (P>0.05). No statistically significant differences were found in the effects of periodontitis, implant site inflammation, and smoking on peri-implant marginal bone resorption (P>0.05). CONCLUSIONS The single taper-retained implant broadens the indications for immediate implant placement in the posterior region, and its deep sub-osseous placement (≥2 mm below the bone) avoids to a certain extent the disturbance of the implant by external stimuli and the exposure of the cervical abutment of the implant, with the good long-term stability of the marginal bone around the implant.
Humans ; Dental Implantation, Endosseous ; Dental Implants ; Immediate Dental Implant Loading ; Follow-Up Studies ; Dental Implants, Single-Tooth ; Alveolar Bone Loss/surgery* ; Treatment Outcome ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure

OBJECTIVE: To compare the effects of resin base and different retention depth on the fracture resistance of mandibular molars restored with nano-ceramic endocrowns. METHODS: Forty mandibular molars selected and randomly divided into 5 groups: ① The control group which was consisted of intact teeth, ② the non-resin base group, ③ the 2 mm retention depth group, ④ the 3 mm retention depth group, ⑤ the 4 mm retention depth group, respectively. After tooth preparation, in vitro root canal therapy was conducted, which was followed by endocrown design, production and adhesive of groups ②-⑤. All the samples were under load (N) of the universal mechanical testing machine after embedding. The fracture pattern of each sample was observed under stereomicroscope. Then the microstructure of the fracture surface was observed by scanning electron microscopy. RESULTS: The fracture loads of each group were respectively: the control group fracture load was (3 069.34±939.50) N; experimental groups: fracture load of (2 438.04±774.40) N for the group without resin base; fracture load of (3 537.18±763.65) N for the group with 2 mm retention depth. The fracture load of the retention depth 3 mm group was (2 331.55±766.39) N; the fracture load of the retention depth 4 mm group was (2 786.98±709.24) N. There was statistical significance in the effect of resin base and different retention depth on the fracture loads of molars restored with nano-ceramic endocrown (P < 0.05). Repairable fractures in each group were as follows: control group 2/8, non-resin base group 1/8, retention depth of 2 mm group 1/8, retention depth of 3 mm group 2/8, and retention depth of 4 mm group 0/8. The effects of the retention depth and the presence of resin base on the fracture resistance of the resin nano-ceramic endocrowns were statistically significant (P < 0.05). Scanning electron microscopy showed more arrest lines and small twist hackles on the fracture surface of the restorations with resin base (retention depths of 2 mm, 3 mm, and 4 mm), with cracks extending towards the root. In addition to the characteristics above, more transverse cracks parallel to the occlusal surface, pointing outwards from the center of the pulp cavity retention, were also observed on the fracture surface of the non-resin base restorations. CONCLUSION When molar teeth with nano-ceramic endocrowns are restored, resin base and the retention depth of 2 mm help the teeth to obtain optimal fracture strength.
Ceramics ; Composite Resins ; Dental Porcelain ; Dental Restoration Failure ; Dental Stress Analysis ; Materials Testing ; Molar

ABSTRACT Implant periapical lesion (IPL) is also known as retrograde peri-implantitis and as the name suggests, it involves inflammation surrounding the apical part of the dental implants. Previously, many studies have reported the event of IPL that further delays osseointegration, and some reported failure of implant placement due to this disease. In this article, we described two cases of early dental implant failure that was associated with active IPL and correlated the clinical and radiographical findings with the histopathological findings.
Dental Restoration Failure ; Dental Implants--adverse effects ; Periapical Tissue

Recently, among the edentulous patients who undergo dental implants, the proportion of hypertensive patients remains high, which poses a greater challenge for clinicians to operate and to maintain the therapeutic effect. The present review comprehensively summarized clinical researches about the adverse effects on dental implants, outlined molecular mechanisms of the positive effects of various antihypertensive drugs on bone metabolism, and proposed that clinicians should select preventive strategies during preoperative and intraoperative procedures according to the blood pressure of patients with hypertension.
Alveolar Bone Loss ; Dental Implantation, Endosseous/methods* ; Dental Implants ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure ; Humans ; Hypertension/surgery* ; Jaw, Edentulous ; Maxilla/surgery* ; Risk Assessment

OBJECTIVE: To evaluate the effects of different edge compensation angles on the fracture strength of multilayer zirconia all-ceramic crowns and traditional uniform zirconia all-ceramic crowns. METHODS: The resin tooth preparation specimen of the mandibular first molar with a knife-edge was fabricated. A 3D digital model of the specimen was obtained by scanning it with a 3D dental model scanner. The 3D digital model was imported into computer aided design (CAD) software, and three 3D digital models of the full crown with the same surface shape are designed with the edge compensation angles of 30°, 45° and 60°, respectively. Then, the designed 3D digital model is imported into computer aided manufacturing (CAM) software. Three kinds of multilayer and homogeneous zirconia all-porcelain crowns with different edge compensation angles were fabricated, 10 each for a total of 60. The fracture load of each crown was measured under the electronic universal testing machine. RESULTS: Fracture load of multilayer and uniform zirconia all-ceramic crowns, (4 322.86±610.07) N and (5 914.12±596.80) N in the 30° group, (5 264.82±883.76) N and (5 220.83±563.38) N in the 45° group and (4 900.42±345.41) N and (5 050.22±560.24) N in the 60° group, respectively. The fracture load of multi-layer zirconia all-ceramic crowns in the 30° group was significantly lower than that of homogeneous zirconia all-ceramic crowns(P < 0.05); there was no statistical significance in 45° group and 60° group(P>0.05). In the multi-layer zirconia all-ceramic crowns: the fracture load of the 30° group was significantly lower than that of the 45° group (P < 0.05); there was no significant difference between the 30° group and the 60° group, the 45° group and the 60° group (P>0.05).In uniform zirconia full crown group: the 30° group was higher than the 45° group, the 30° group was higher than the 60° group (P < 0.05), and there was no significant difference between the 45° group and the 60° group (P>0.05). CONCLUSION The fracture loads of three kinds of uniform and multilayer zirconia all ceramic crowns with different edge compensation angles can meet the clinical requirements. A smaller edge compensation angle is recommended when using traditional zirconia all-ceramic crowns, while 45° is recommended when using multi-layer zirconia all-ceramic crowns.
Ceramics ; Computer-Aided Design ; Crowns ; Dental Porcelain ; Dental Prosthesis Design ; Dental Restoration Failure ; Dental Stress Analysis ; Flexural Strength ; Materials Testing ; Zirconium

OBJECTIVE: To analyze the clinical curative effect after 5-year follow-up of single tooth implant-supported restorations in the posterior region. METHODS: In the study, patients with single tooth implant-supported restorations in the posterior region after loading 5-year in the Second Clinical Division of Peking University School and Hospital of Stomatology from October 2005 to May 2010 was enrolled. The implant survival rate, prosthetic conditions (including the structural integrity or loosening of the prosthesis, the retention of the materials used to fill access holes of screw-retained implant crowns, loosening or fractures of the implant abutment or screw) and marginal bone lever level around implants were determined by clinical and radiographic examination. RESULTS: The study was composed of 215 patients, the mean age was 48.6 years (range: 27 to 71), and 321 soft tissue implants were inserted. There were 9 implants loose and lost during the visit, the cumulative success rate was 97.2%. In the 312 remaining implants, 120 implants were placed in the upper jaws (38.5%) and 192 in the lower jaws (61.5%). Three different diameters as 3.3 mm (5 implants), 4.1 mm (115 implants) and 4.8 mm (192 implants) and three different lengths as 8 mm (21 implants), 10 mm (206 implants) and 12 mm (85 implants) were used, respectively. 277 (88.8%) cement-retained and 35 (11.2%) screw-retained implant-supported single crowns were made. The marginal bone loss (MBL) around dental implants after loading 5 years in the mesial and distal sides were (0.73±0.25) mm and (0.78±0.26) mm, respectively. There was no significant difference among MBL and bone quality, implant type, angle of abutment, prosthodontic type, crown-to-implant ratio, gender, and age of the patients (P > 0.05). The major mechanical complications after restoration involved loosening (8.6%) and fracture (2.9%) of the crown retainer screw, loss of resin covering the screw (11.4%), and the most frequent mechanical complications were loss of crown retention (14.1%) and fracture of porcelain (13.8%). The incidence of loss of crown retention was correlated with insufficient clinical crown height or using angle abutment (P < 0.05). CONCLUSION After loading 5 years, the bone level around the soft-tissue-implant placed in posterior region was stable. To minimize the frequency of mechanical complications after restoration, protocols must be established from diagnosis to the completion of treatment and follow up of implant-supported prostheses, especially in terms of adequate technical steps and careful radiographic evaluation of the components.
Crowns ; Dental Implants ; Dental Implants, Single-Tooth ; Dental Prosthesis Design ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure ; Follow-Up Studies ; Humans ; Middle Aged ; Survival Rate

OBJECTIVE: This study aimed to investigate the effect of occlusal thickness design on fracture resistance of endocrowns restored with lithium disilicate ceramic and zirconia. METHODS: A total of 24 artificial first mandibular molars were randomly divided into four groups with six teeth in each group as follows: group lithium disilicate ceramic-2 mm (lithium disilicate ceramic, with an occlusal thickness of 2 mm and a retainer length of 4 mm); group lithium disilicate ceramic-4 mm (lithium disilicate ceramic, with an occlusal thickness of 4 mm and a retainer length of 2 mm); group zirconia-2 mm (zirconia, with an occlusal thickness of 2 mm and a retainer length of 4 mm); and group zirconia-4 mm (zirconia, with an occlusal thickness of 4 mm and a retainer length of 2 mm). After adhesive cementation (RelyX Ultimate Clicker), all specimens were subjected to thermocycling (10 000 cycles). The specimens were subjected to fracture resistance testing at a 135° angle to the teeth at a crosshead speed of 0.5 mm·min⁻¹ in a universal testing machine. Data were analyzed with ANOVA and Tukey's HSD test by SPSS 15.0. The failure modes were classified. RESULTS: The fracture resistances of groups lithium disilicate ceramic-
2 mm, lithium disilicate ceramic-4 mm, zirconia-2 mm, and zirconia-4 mm were (890.54±83.41), (2 320.87±728.57), 
(2 258.05±557.66), and (3 847.70±495.99) N respectively. Group zirconia-4 mm had the highest fracture resistance, whereas group lithium disilicate ceramic-2 mm had the lowest. CONCLUSIONS The fracture resistance of molar endocrown with zirconia is higher than that with lithium disilicate ceramic. Increasing the occlusal thickness can improve the fracture resistance but increase the risk of fracture of abutment.
Ceramics ; Crowns ; Dental Porcelain ; Dental Restoration Failure ; Dental Stress Analysis ; Materials Testing ; Zirconium

With the comprehensive application and development of implant dentistry in recent years, multi-institutional data have supported a large number of clinical research findings. A consensus was gradually reached on the evaluation of the state and effect of implants and types of indicators that were selected after restoration. This study aims to examine the frequently used criteria to define treatment success in implant dentistry.
Dental Implants ; Dental Prosthesis Design ; Dental Prosthesis, Implant-Supported ; Dental Restoration Failure ; Treatment Outcome

OBJECTIVE: This study aims to investigate the fracture resistance and short-term restorative effects of resin-bonded fixed partial dentures (RBFPDs) made from heat-pressed lithium-disilicate-based glass-ceramic (IPS e.max press) and zirconia ceramic (WIELAND) and retained by all-ceramic guiding plates when used to restore missing mandibular second premolars. METHODS: A total of 64 human mandibular first premolars and first molars were prepared as abutments, then were randomly divided into 4 groups (n=8): E0, heat-pressed ceramic RBFPDs, no cyclic loading; E1, heat-pressed ceramic RBFPDs exposed to 300 000 cycles of dynamic loading; W0, zirconia ceramic RBFPDs, no cyclic loading; and W1, zirconia ceramic RBFPDs exposed to 300 000 cycles of dynamic loading. Fracture strength was tested in a universal testing machine. RESULTS: The medians of fracture strength were 1 242.85 N±260.11 N (E0), 1 650.85 N±206.77 N (W0), 1 062.60 N±179.98 N (E1), and 1 167.61 N±265.50 N (W1). Statistical analysis showed that all the groups exhibited significantly higher fracture strength compared with the maximum bite force in the premolar region (360 N; P<0.001). The W0 group had significantly higher fracture strength than the E0 group (P<0.05). Meanwhile, no significant difference in fracture strength was observed between the E1 and W1 groups (P>0.05). Significant statistical differences were found between the zirconia ceramic groups (W0 and W1, P<0.05) but not between the glassceramic groups (E0 and E1, P>0.05) after dynamic loading. CONCLUSIONS The RBFPDs retained by all-ceramic guiding plates exhibited promising fracture properties and optimal short-term restorative effects when used to restore missing mandibular second premolars.
Bicuspid ; Ceramics ; Dental Porcelain ; Dental Restoration Failure ; Dental Stress Analysis ; Denture Design ; Denture, Partial, Fixed ; Denture, Partial, Fixed, Resin-Bonded ; Humans ; Materials Testing ; Zirconium

OBJECTIVE: To evaluate the sinus bone gains after sinus floor elevation procedures with or without grafts when implants were placed simultaneously. METHODS: The research included 26 edentulous patients in the maxillary posterior region, who were divided into 2 different groups according to the sinus lift procedures employed: group of osteotome sinus floor elevation with bone grafts (group A) and group of osteotome sinus floor elevation without bone grafts (group B). The implants were placed simultaneously, and were followed for a period of 30-50 months after sinus floor elevation as routine and then were observed for sinus bone change. RESULTS: There were 27 implants (13 implants for group A and 14 implants for group B) and the following time was 40.23 (36.20, 48.07) months. The residual bone height (RBH) was (6.64±1.21) mm for group A and ( 6.96±1.36) mm for group B; the difference between the two groups was not statistically significant (P=0.459).The sinus bone gain (SBG) when followed was (2.20±1.71) mm for group A, and 1.77 (0.94, 2.05) mm for group B; the difference between the two groups was not statistically significant (P = 0.583). The quality of apical bone around implant apex was divided into 3 categories which were excellent, fine and fair.The quality of apical bone around implant apex was excellent and fine for 9 implants in group A and 8 implants in group B, and the difference between the two groups was not statistically significant (Fisher exact test, P=0.695).The implant apex when followed was (0.09±1.32) mm below the new sinus floor for group A and (0.03±0.91) mm for group B, and the difference between the two groups was not statistically significant (P = 0.898). The SBG for the total was 1.85 (1.10, 2.20) mm. The SBG was statistically significantly only related to the protrusion height of the implant apex (r=0.383, P=0.049). CONCLUSION Sinus floor elevation procedures with or without grafts can all gain good results. The SBG is related to the protrusion height of the implant apex significantly.
Dental Implantation ; Dental Implantation, Endosseous ; Dental Implants ; Dental Restoration Failure ; Humans ; Maxilla ; Retrospective Studies ; Sinus Floor Augmentation