BACKGROUND:Stem cell mesenchyme within reactive softtissues has the potential to promote tissue regeneration.Demineralized dentin matrix,which has good biocompatibility,can be used as a scaffold material for the site preservation surgery to promote the attachment,proliferation,and differentiation of osteoblasts.OBJECTIVE:To evaluate the changes in alveolar bone height and width after 6 months of site preservation with demineralized dentin matrix after 1 month of extraction of affected teeth with preservation of reactive softtissues.METHODS:A total of 38 patients with 62 extraction sites were included.One month after the extraction of the affected teeth with preservation of reactive soft tissues,demineralized dentin matrix was used to perform site-preservation surgery.Cone-beam CT was taken preoperatively,immediately postoperatively,and 6 months postoperatively to measure the proximal-medial bone height,central bone height,distal-medial bone height,buccal bone height,lingual bone height,and alveolar bone height,and alveolar bone width.Extraction defects were categorized as one-,two-,three-,or four-wall defects based on the number of alveolar fossa bone walls remaining after tooth extraction.Changes in bone volume were compared preoperatively,immediately postoperatively,and 6 months postoperatively.RESULTS AND CONCLUSION:No wound infection occurred at any site during bone healing.Compared with preoperative data,there was a significant increase in alveolar bone height and bone immediately postoperatively(P<0.05);there was also an increase in alveolar bone height but no change in alveolar bone width 6 months postoperatively(P>0.05).Compared with the immediate postoperative period,alveolar bone width was increased by(1.253±2.896)mm 6 months postoperatively,but there was no change in alveolar bone height(P>0.05).The bone height of the four bone defect types was significantly increased immediately and 6 months postoperatively(P<0.05),and no changes in the bone width were observed(P>0.05).Compared with the preoperative data,there was the least increase in proximal-medial bone volume in one-wall bone defects at 6 months postoperatively(P<0.05)and the most increase in proximal-medial bone volume in two-wall bone defects(P<0.05).These findings indicate that demineralized dentin matrix applied to site preservation can effectively prevent and slow down alveolar bone resorption after tooth extraction,and can rebuild the alveolar bone contour where resorption has occurred to a certain extent;preservation of reactive tissues applied to demineralized dentin matrix site preservation after tooth extraction can achieve wound closure with good clinical efficacy;demineralized dentin matrix applied to the alveolar socket site preservation with one-,two-,three-,and four-wall defects shares similar effects.However,demineralized dentin matrix is more effective for site preservation when applied to extraction sockets with intact bone walls.

BACKGROUND:Stem cell mesenchyme within reactive softtissues has the potential to promote tissue regeneration.Demineralized dentin matrix,which has good biocompatibility,can be used as a scaffold material for the site preservation surgery to promote the attachment,proliferation,and differentiation of osteoblasts.OBJECTIVE:To evaluate the changes in alveolar bone height and width after 6 months of site preservation with demineralized dentin matrix after 1 month of extraction of affected teeth with preservation of reactive softtissues.METHODS:A total of 38 patients with 62 extraction sites were included.One month after the extraction of the affected teeth with preservation of reactive soft tissues,demineralized dentin matrix was used to perform site-preservation surgery.Cone-beam CT was taken preoperatively,immediately postoperatively,and 6 months postoperatively to measure the proximal-medial bone height,central bone height,distal-medial bone height,buccal bone height,lingual bone height,and alveolar bone height,and alveolar bone width.Extraction defects were categorized as one-,two-,three-,or four-wall defects based on the number of alveolar fossa bone walls remaining after tooth extraction.Changes in bone volume were compared preoperatively,immediately postoperatively,and 6 months postoperatively.RESULTS AND CONCLUSION:No wound infection occurred at any site during bone healing.Compared with preoperative data,there was a significant increase in alveolar bone height and bone immediately postoperatively(P<0.05);there was also an increase in alveolar bone height but no change in alveolar bone width 6 months postoperatively(P>0.05).Compared with the immediate postoperative period,alveolar bone width was increased by(1.253±2.896)mm 6 months postoperatively,but there was no change in alveolar bone height(P>0.05).The bone height of the four bone defect types was significantly increased immediately and 6 months postoperatively(P<0.05),and no changes in the bone width were observed(P>0.05).Compared with the preoperative data,there was the least increase in proximal-medial bone volume in one-wall bone defects at 6 months postoperatively(P<0.05)and the most increase in proximal-medial bone volume in two-wall bone defects(P<0.05).These findings indicate that demineralized dentin matrix applied to site preservation can effectively prevent and slow down alveolar bone resorption after tooth extraction,and can rebuild the alveolar bone contour where resorption has occurred to a certain extent;preservation of reactive tissues applied to demineralized dentin matrix site preservation after tooth extraction can achieve wound closure with good clinical efficacy;demineralized dentin matrix applied to the alveolar socket site preservation with one-,two-,three-,and four-wall defects shares similar effects.However,demineralized dentin matrix is more effective for site preservation when applied to extraction sockets with intact bone walls.

Objective This test aimed to investigate the factors affecting the locking force between the implant and abutment and the amount of abutment subsidence in pure Morse taper connection implant systems.Methods With ref-erence to the Bicon implant abutment connection design,different types of implant specimens and their corresponding types of abutments were fabricated.The implant-abutment locking taper was uniformly 1.5°.The locking depths were 1.0,2.0,and 3.0 mm.The diameters of the locking column were 2.5,3.0,and 3.5 mm.The thicknesses of the outer wall of the implant were 0.15 and 0.30 mm.The loading forces of the testing machine were 200,300,and 400 N.At least 10 specimens of each group of implant-abutment were used.All specimens were loaded in the same manner using a univer-sal testing machine(finger pressure + specified loading force,five times).The total height of the implant-abut-ment was measured before finger pressure,after finger pressure,and after the testing machine was loaded for five times to calculate the amount of sinking of the abutment.Finally,the implant and abutment were pulled apart using the universal testing machine,and the subluxation force was observed and recorded.Results The test loading force,locking depth,and locking post diameter had an effect on the implant-abutment locking force and abutment subsidence.The implant-abutment locking force increased with the increase in the test loading force,locking depth,and locking post diameter(R=0.963,0.607,and 0.372,respectively),with the test loading force having the most significant effect.Abut-ment subsidence increased with the increase in test loading force(R=0.645)and decreased with the increase in locking depth and locking post diameter(R=-0.807 and-0.280,respectively),with locking depth having the most significant ef-fect on abutment subsidence.No significant correlation was found between the thickness of the outer wall of the implant and the change in the magnitude of the implant-abutment locking force.However,an increase in the thickness of the out-er wall of the implant decreased the amount of abutment subsidence,which was inversely correlated.Conclusion The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection im-plant-abutment connection,increasing the locking depth and locking post diameter,and increasing the amount and num-ber of times the abutment is loaded during seating.Problems,such as loosening or detachment of the abutment,can be re-duced.The recommended abutment to be loaded should be no less than five times during seating to prevent the abutment from sinking and causing changes in the occlusal relationship in the later stages.Preliminary occlusal adjustments should only be conducted in the early stages of the use of temporary restorations,and final restorations and occlusal adjustments are recommended to be performed after using the abutment for a period of time.

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

Epidermoid cysts are generally benign neoplastic lesions, the etiology of which is unclear and is mainly related to epithelial cells left in the tissues during the embryonic period and traumatically implanted in the tissues. The most common intraosseous sites are the phalanges and the skull. Epidermoid cysts occurring in the jaws are clinically rare. In this paper, we report a case of epidermoid cyst occurring in the mandible with embedded teeth and discuss the etiology, clinical manifestations, diagnosis, and treatment of epidermoid cysts in the jaws in the context of the relevant literature.
Humans ; Epidermal Cyst/surgery* ; Skull ; Mandible ; Diagnosis, Differential ; Epithelial Cells