Experimental study on implant-abutment locking force and abutment subsidence in a pure Morse taper connection implant system.

OBJECTIVES: 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 reference 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 universal testing machine (finger pressure + specified loading force, five times). The total height of the implant-abutment 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. Abutment 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 effect 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 outer wall of the implant decreased the amount of abutment subsidence, which was inversely correlated. CONCLUSIONS: The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection implant⁃abutment connection, increasing the locking depth and locking post diameter, and increasing the amount and number of times the abutment is loaded during seating. Problems, such as loosening or detachment of the abutment, can be reduced. 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.

[Effects of cortical bone thickness and jaw bone density on pain during implant surgery].

PURPOSE: To investigate the effects of different cortical bone thickness and jaw bone density at implant sites on intraoperative pain during implant surgery. METHODS: One hundred and eighty-seven patients(263 implant sites) who underwent implant placement surgery at the Fourth Affiliated Hospital of Nanchang University from August 2021 to August 2022 were selected to investigate the effects of different cortical bone thickness and jaw bone density HU values at implant sites on the anesthetic effect under local infiltration anesthesia with epinephrine in articaine. SPSS 26.0 software package was used for data analysis. RESULTS: The mean cortical bone thickness at the painful sites[(3.90±1.36) mm] was significantly greater than that at the non-painful sites [(2.24±0.66) mm], and the difference was statistically significant(P＜0.05). The differences in cortical bone thickness in the mandibular anterior, premolar, and molar regions were statistically significant in the comparison of pain and non-pain sites. The mean HU value of bone density was (764.46±239.75) for the painful sites and (612.23±235.31) for the non-painful sites, with significant difference(P＜0.05). The difference was not significant(P＞0.05) when comparing the HU values of painful sites with non-painful sites in the mandibular anterior teeth and anterior molar region, while the difference was significant(P＜0.05) when comparing the HU values of painful sites with non-painful sites in the mandibular molar region. CONCLUSIONS: Sites with large cortical bone thickness have a greater effect on blocking infiltrative anesthetic penetration and are more prone to intraoperative pain during implantation. In the mandibular anterior and premolar regions, the HU value of the implant sites had less effect on infiltrative anesthetic penetration, and the effect was greater in the mandibular molar region, and the implant sites with high HU values in the mandibular molar region were more likely to have intraoperative pain. When the cortical bone thickness in the planned implant site is greater than 3.9 mm and the mean bone density in the mandibular molar region is greater than 665 HU. If there is sufficient safe distance for hole operation, it is recommended to apply mandibular nerve block anesthesia combined with articaine infiltration anesthesia to avoid intraoperative pain and bad surgical experience for the patients.

Peri-implant epidermoid cyst: A case report and literature analysis.

BACKGROUND: A peri-implant cystic lesion is a rare finding, and to date most investigators have considered that its pathogenesis is caused by trauma and infection related to dental implantation. However, the pathogenesis of these cysts remains unclear and is recognized to have multifactorial origins. CASE PRESENTATION: In February 2021, a 75-year-old male patient underwent implant restoration due to mobility of the left maxillary central incisor. The implant achieved good osseointegration and was successfully restored. However, in March 2023, the patient sought treatment due to mobility of the dental implant. Clinical examination showed that the implant had loosened in three directions (vertical, mesial-distal, and labial-lingual), and the peri-implant mucosa was slightly red and swollen. Radiographic examination (cone beam computed tomography) showed a large radiolucent area with clear boundaries involving the cervical and middle portions of the dental implant, and white bone lines were observed at the edge of the low-density shadow. Intraoperatively, we removed the patient's implant, performed a complete debridement, and conducted bone augmentation surgery in the area of bone defect. Postoperatively, the patient recovered well. The final histopathological result confirmed an epidermoid cyst. CONCLUSIONS: Peri-implant epidermoid cyst is a rare complication that affects the long-term outcome of implant therapy. This case serves as a warning to clinicians to avoid involving epithelial tissue in the implant site during implant surgery, in order to prevent the potential occurrence of a peri-implant epidermoid cyst, thereby creating better conditions for the patient's recovery and the long-term efficacy of the implant.

A case of intramandibular epidermoid cyst and literature analysis.

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.

Clinical efficacy of simple taper retentive implants in immediate posterior dental implantation for 5-7 years.

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.

[Analysis of clinical effects and risk factors of short implant followed up for 7-9 years].

PURPOSE: To evaluate the long-term clinical efficacy of short implants and analyze the influencing factors of the survival rate. METHODS: A total of 178 patients who received implant therapy in the Department of Stomatology, the Fourth Affiliated Hospital of Nanchang University from January 2010 to December 2014 were selected, including 334 short implants of Bicon (implant length ≤6 mm). The basic condition, restoration design, short implant survival rate and complications were observed and analyzed. SPSS 24.0 software package was used for data analysis. RESULTS: The average follow-up time of short implants was 96±17 months. During the observation period, 20 implants failed, 1 implant had mechanical complications and 6 implants had biological complications. Based on the analysis of implants and patients, the long-term cumulative survival rate of short implants was 94.0%(over 5 years survival rate was 96.4%) and 90.4% respectively. There was no significant difference between the survival rate of short implants and the patient's gender, age, whether to use special operation and the type of jaw teeth(P＜0.05). Smoking and periodontitis were risk factors for failure of short implants(P＜0.05).The difference of short implant survival rate between short implants restoration with combined crowns and single crowns was statistically significant(P＜0.05). The survival rate of short implant in mandible was higher than that in maxilla(P＜0.05). CONCLUSIONS: Under the standards clinical program and operation, short implant can be used to shorten the implant restoration cycle and avoid complicated bone augmentation which can achieve good long-term clinical effect. Short implant should be used to strictly control the risk factors that affect the survival of short implant.

Clinical observation of a narrow alveolar ridge in the anterior area with a simple taper retention implant.

OBJECTIVES: This study aims to determine the clinical effect of an external attachment implant, called JUST J1 MINI (hereafter referred to as J1 implant), with simple tonal retention on the narrow alveolar area of the anterior teeth (4.5-5.5 mm). METHODS: A total of 27 J1 implants were implanted in 12 patients in the Fourth Affiliated Hospital of Nanchang University who were treated with narrow alveolar ridge implants. In the absence of any bone increment, all the implants were implanted with tonal retention external connection, and the survival rate of the implants was evaluated using Wheeler retention standard. The average observation period was 24 months. The amount of bone absorption at the edge of the implant, abutment abscission rate, and fracture/fracture and loosening of the implant were observed. RESULTS: The marginal bone uptake of the 27 J1 implants in 12 patients was (0.069±0.032) mm 6 months after implantation and (0.142±0.079) mm 24 months after implantation. No significant difference in marginal bone uptake was observed between the implants 6 months and 24 months after implantation. No loosening of the abutment was found, and implant retention rate was 100% during the observation period. CONCLUSIONS: The application of JUST J1 MINI to the narrow alveolar ridge in the anterior area can achieve a simple aesthetic effect within a short period under the condition of no bone increment.

Displacement of the full body of a dental implant into the sinus space without membrane perforation and subsequent osseointegration: a case report.

An increasing number of studies have investigated the use of osteotome sinus floor elevation (OSFE) with simultaneous implant placement for maxillary sinus floor residual bone height (RBH) <4 mm. Many studies have reported good clinical results, but very few have reported complications related to this procedure. Here, the case of a 50-year-old female patient with an RBH in the left upper posterior region of 1-4 mm, who underwent OSFE with simultaneous placement of three Bicon short® implants, is described. One of the implants was found to be displaced during the second-stage surgery. The displaced implant was removed using piezosurgery, OSFE with simultaneous implant placement was repeated, and the missing tooth was reconstructed 6 months later. This case suggests that OSFE with simultaneous implant placement is feasible for severely atrophic maxillary sinus floor, but carries a risk of implant displacement.

[Retrospective study on transcrestal sinus floor elevation with simultaneous implantation of short implants].

OBJECTIVE: To explore the changes in bone height of the maxillary sinus floor at different sinus ridge heights after transcrestal sinus floor elevation (tSFE) with the simultaneous implantation of short implants. METHODS: A total of 74 Bicon short implants were implanted into 37 patients during the same period of maxillary sinus elevation. The residual bone height (RBH)<4 mm group has 43 sites, and the RBH≥4 mm group has 31 sites. After 5 years of follow-up observation, the implant survival rate and the change in bone height achieved in the maxillary sinus over time were measured and analyzed via clinical examination and X-ray imaging. RESULTS: In the 74 implantation sites, the elevation height of the sinus floor was (6.64±1.32) mm and the bone height of the sinus floor was (3.35±1.29) mm 5 years after loading. No statistical difference was observed in the bone resorption of the implant neck between the RBH<4 mm and RBH≥4 mm groups. Meanwhile, a statistical difference was noted in the bone height obtained in the maxillary sinus between the two groups. CONCLUSIONS: When RBH in the maxillary posterior tooth area was <4 mm, the simultaneous implantation of Bicon short implants with tSFE can achieve a high implant survival rate and bone gain in the maxillary sinus, but does not increase the absorption of the alveolar ridge bone.

Unconventional implant strategy for patients with a limited interocclusal space in the posterior region: a case report.

BACKGROUND: Implant prostheses require sufficient interocclusal space. In cases of limited interocclusal space, reducing or extracting over-erupted opposing teeth, orthodontic intrusion, or surgical reconstruction of the edentulous space are commonly used to restore the interocclusal space. However, there are disadvantages to these approaches. CASE PRESENTATION: The present case report describes a patient with a limited interocclusal space managed using an unconventional implant strategy. CONCLUSIONS: The patient presented satisfactory outcomes without any signs of implant failure, suggesting that the unconventional implant treatment strategy is a useful option for patients with a limited interocclusal space in the posterior region. This unconventional implant surgery provides a minimally invasive treatment alternative.