• Journal of Periodontal and Implant Science
• /
• v.47 no.2
• /
• pp.106-115
• /
• 2017

Purpose: The possibility of immediate or early loading has become popular in implant dentistry. A prerequisite for the immediate or early loading of an implant prosthesis is the achievement of initial stability in the implant. Moreover, in response to clinicians' interest in verifying clinical stability to determine the optimal time point for functional loading, a non-invasive method to assess implant stability has been developed on the basis of resonance frequency analysis (RFA). The primary objective of this study was to monitor the stability of sandblasted, large-grit, and acid-etched (SLA) implants with different diameters during the early phases of healing by RFA. The secondary objective was to evaluate how the initial stability of implants varied depending on different surface modifications and other contributing factors. Methods: Thirty-five implants (25 SLA implants and 10 resorbable blasting media [RBM] implants) placed in 20 subjects were included. To measure implant stability, RFA was performed at baseline and at 1, 2, 3, 4, 6, and 10 weeks after surgery. Results: The longitudinal changes in the implant stability quotient (ISQ) values were similar for the SLA implants with different diameters and for the RBM implants. During the initial healing period, the ISQ decreased after installation and reached its lowest values at 1 week and 2 weeks, respectively. The mean ISQ values in the SLA implants were significantly higher in ${\varnothing}5.0mm$ implants than in ${\varnothing}4.0mm$ implants. Men showed a higher ISQ than women. Mandibular sites showed a higher ISQ than maxillary sites. Conclusions: All implants used in this study are suitable for immediate or early loading under appropriate indications. A wider diameter and SLA surface treatment of implants could improve the stability, if the implant is fixed with at least 30 Ncm of insertion torque.

• The Journal of Advanced Prosthodontics
• /
• v.10 no.5
• /
• pp.388-394
• /
• 2018

PURPOSE. To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS. Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at $10N{\cdot}cm$, simulating hand tightening, and then at the manufacturers' recommended torque ($30N{\cdot}cm$) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS. Significant differences were observed in axial displacement according to the type of implant-abutment connection (P<.001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P<.05). CONCLUSION. Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

• The Journal of Advanced Prosthodontics
• /
• v.13 no.6
• /
• pp.343-350
• /
• 2021

PURPOSE. The success of an implant-prosthetic rehabilitation is influenced by good implant health and an excellent implant-prosthetic coupling. The stability of implant-prosthetic connection is influenced by the rotational tolerance between anti-rotational features on the implant and those on the prosthetic component. The aim of this study is to investigate the rotational tolerance of a conical connection implant system and its titanium abutment counterpart, in various conditions. MATERIAL AND METHODS. 10 preparable titanium abutments, having zero-degree angulation (MegaGen, Daegu, Korea) with an internal 5-degree conical connection, and 10 implants (MegaGen, Daegu, Korea) were used. Rotational tolerance between the connection of implant and titanium abutments was measured through the use of a tridimensional optics measuring system (Quick Scope QS250Z, Mitutoyo, Kawasaki, Japan) in the as-received condition (Time 0), after securing with a titanium screw tightening at 35 Ncm (Time 1), after tightening 4 times at 35 Ncm (Time 2), after tightening one more time at 45 Ncm (Time 3), and after tightening another 4 times at 45 Ncm (Time 4). RESULTS. The group "Time 0" had the lowest values of rotational freedom (0.22 ± 0.76 degrees), followed by the group Time 1 (0.46 ± 0.83 degrees), the group Time 2 (1.01 ± 0.20 degrees), the group Time 3 (1.30 ± 0.85 degrees), and the group Time 4 (1.49 ± 0.17 degrees). CONCLUSION. The rotational tolerance of a conical connection is low in the "as received" condition but increases with repetitive tightening and with application of a torque greater than 35 Ncm.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.1
• /
• pp.55-62
• /
• 2023

For fully edentulous patients, implant-supported overdenture can be considered to enhance chewing efficiency and denture stability. Implant planning software can be used to fabricate a surgical guide for a more precise consideration of anatomic factors and prediction of the shape of definitive prosthesis. Though there are many possible attachments for implant overdenture, milled bar can be useful due to its splinting effect of implants and rigid support of overdenture. This report presents a case of implant-supported milled bar overdenture after guided implant surgery performed with two surgical guide that was fabricated before and after bone reduction.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• v.49 no.5
• /
• pp.278-286
• /
• 2023

Objectives: This review assessed the performance of implant-supported fixed hybrid prostheses in 21 patients who received a total of 137 implants between 2003 and 2010. The implants were evaluated for marginal bone resorption, complications, success rate, and survival rate based on their vertical angularity, type of bone graft, and measured implant stability. Materials and Methods: One-way ANOVA and chi-square tests were used to analyze the relationships among long-term evaluation factors and these variables. The mean initial bone resorption in the implant group with a vertical angle of more than 20° was 0.33 mm and mean final bone resorption was 0.76 mm. In contrast, the mean initial bone resorption in the implant group with a vertical angle of less than 10° was 1.19 mm and mean final bone resorption was 2.17 mm. Results: The results showed that mean bone resorption decreased with an increase in the vertical placement angle of the implants used in fixed hybrid prostheses, as well as in the group without additional bone grafts and those with high implant stability. The success rate of implants placed after bone grafting was found to be higher than those placed simultaneously. Conclusion: These results suggest that implant-supported fixed hybrid prostheses may be an effective treatment option for edentulous patients, and intentionally placing implants with high angularity may improve outcomes.

• The Journal of Korean Academy of Prosthodontics
• /
• v.55 no.3
• /
• pp.272-278
• /
• 2017

Purpose: The aim of the present prospective clinical study was to assess the cumulative survival rate (CSR) of Neobiotech implants restored with fixed partial prosthesis in relation to its potential risk factors. Materials and methods: Thirty six partially edentulous patients received Neobiotech implants and implant supported fixed partial prosthesis at Korea University Guro Hospital Dental Center from November 2009 until November 2011. The observation period was set from the implant placement and the last clinical visit until December 2015. Implant survival rate was determined using the Kaplan-Meier method. The relationship between implant survival rate and the potential risk factors were analysed using the multi Cox proportional analysis (P<.05). Results: A total of 69 implants were placed in 36 patients after a mean observation period of 45.9 months. Two out of 69 implants failed before loading, yielding a 5-year cumulative survival rate of 97.1%. The maxillary implants have a lesser CSR than the mandibular implants based on log rank test analysis (maxilla=91.3%; mandible=100% P<.05). However, the multi Cox proportional analysis showed that implant location has no significant correlation with implant failure (P>.05). Conclusion: Neobiotech implants showed predictable results with a 5 year cumulative survival rate of 97.1%.

• Journal of Periodontal and Implant Science
• /
• v.33 no.3
• /
• pp.349-358
• /
• 2003

The success of dental implant therapy relies mainly upon the presence and maintenance of bone adjacent to implant. An 1-year prospective study was performed, upon the patients who were diagnosed as having chronic adult periodontitis, and had been treated with dental implant. The purpose of this study was to measure the radiographic bone level changes proximal to Astra Tech Single Tooth Implants (ATST, Astra Tech AB, $M{\"{o}}lndal$, Sweden) with microthread and Astra Tech TiOblast Implant (ATTB) without microthread supporting fixed partial prosthesis. Measurements were used to determine mean marginal bone loss during the first year of loading, 17 subjects with its partial prosthesis supported by 37 implants were followed up for an 1-year period. The marginal bone loss of implants was positively correlated with the retention factor, microthread($Microthread^{TM}$) in crestal area of ATST. The results were as follows. 1. The mean marginal bone loss of ATST was 0.226${\pm}$0.395mm, while ATTB was 0.440${\pm}$0.360mm. There was a statistically significant difference between ATST and ATTB (p<0.05). 2. The mean bone loss of the upper jaw fixtures was 0.269${\pm}$0.265mm for ATST and 0.529${\pm}$0.417mm for ATTB . There was a statistically significant difference between ATST and ATTB (p<0.05). In the lower jaw the corresponding figures were 0.167${\pm}$0.231mm and 0.313${\pm}$0.214mm, respectively. There was no significant difference between ATST and ATTB (p>0.05). 3. The mean bone loss of ATST was lower than that of ATTB at all sites according to bone quality. There was a statistically significant difference between ATST and ATTB at bone quality type III(p <0.05). In conclusion, the mean bone loss of ATST was smaller than that of ATTB . Therefore, the retention factor of crestal area, microthread ($Microthread^{TM}$) was effective to maintenance of marginal bone level around fixture.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.3
• /
• pp.212-217
• /
• 2018

Purpose: This study was to assess clinically the incidence of abutment screw loosening of posterior implant-supported fixed prosthesis and its affecting factors. Materials and methods: 391 implant-supported crowns restored from January 2013 to January 2016 were included in this study. All restorations were fabricated with either a single crowns or a splinted crown, and cemented with temporary cement. The incidence of abutment screw loosening is investigated and gender, restoration position, opposing teeth, restoration type, abutment connection type were assessed as possible factors affecting abutment screw loosening. Results: During the observation period (2 - 5 years), abutment screw loosening was found in 29 restorations (7.4%). It took 3 to 48 months (means 19.5 months) to loose the screw, and three of these implants were fractured. Among the factors considered, there were statistically significant differences at abutment screw loosening rate between molar group (9.4%) and premolar group (2.6%) (P<.019). According to the type of opposing teeth, there were statistically significant differences between nature teeth (74.7%) and implant (25.0%), removable denture (3%) (P<.019). The other possible factors did not have a significant effect on loosening of the abutment. Conclusion: The incidence of abutment screw loosening in posterior restoration was 7.4%. Abutment screw loosening were more likely to occur in molars group than premolar group, and according to the opposing teeth, there were the greatest frequency in nature teeth than implant and removal denture. There was a statistically significant difference.

• The Journal of the Korean dental association
• /
• v.47 no.11
• /
• pp.758-768
• /
• 2009

Purpose : Schulte introduced immediate implant cases in 1970s, since then many patients have been treated by immediate implants. The aim of this study was to evaluate the cumulative survival rate of immediate implant and to analyze various factors associated with survival of immediate implant in a 8-year period retrospectively. Materials and methods : From May, 2000 to October, 2007, 77 implants were placed in 63 patients immediately after tooth extraction at Department of Periodontology, Yonsei University Hospital. The implant survival rate was analyzed using a life-table analysis. After delivery of prosthesis, along 1 year of observation period, all implants were evaluated clinically and radiographically. Results : Among 77 implants, 59 were placed in maxilla and 18 in mandible. The most common site of the implantation was Mx anterior (65%). The overall survival rate was 94.8% over a mean follow-up period of $44.2{\pm}21$ months and the 8-year cumulative survival rate was 94.6%. Failure occurred in 4 implants, all of which were due to early failures. None of the following factors were significantly associated with the survival of immediate implants: advanced surgical technique including bone graft and guided bone regeneration, the types of implants, causes of tooth loss, and types of prosthesis. Conclusion : On the basis of 8-year life time analysis, immediate implant placement can be considered a safe and predictable treatment mordality.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.1
• /
• pp.42-51
• /
• 2022

Esthetic restoration of maxillary anterior implant heavily depends on the direction of installation of implant fixture. In patients with malpositioned implant, it is crucial to communicate the limitations of prosthetic outcome with the patient before starting on a restoration. To facilitate the communication, three-dimensional virtual representation by superimposing facial and intraoral digital scans with Computed Tomography (CT, dicom file) was used for visualization of the limitations of prosthesis. Through digital diagnostic wax-up, the profile of right maxillary anterior incisor implant was expected to be protrusive, which the patient was not satisfied with. Since the patient already had done root canal treatment on left maxillary anterior incisor due to previous trauma, a new prosthetic design including both right and left maxillary anterior incisors was presented to the patient. The second design was chosen and his comments were delivered to dental lab. The patient was satisfied with the new prosthesis, aesthetically and functionally.