• The Journal of Korean Academy of Prosthodontics
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• v.59 no.1
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• pp.79-87
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• 2021

The digital workflow of optical impressions by the intraoral scanner and CADCAM manufacture of dental prostheses is actively developing. The complex process of traditional impression taking, definite cast fabrication, wax pattern making, and casting has been shortened, and the number of patient's visits can also be reduced. Advances in intraoral scanner technology have increased the precision and accuracy of optical impression, and its indication is progressively widened toward the long span fixed dental prosthesis. This case report describes the long span implant case, and the operator fully utilized digital workflow such as computer-guided implant surgical template and CAD-CAM produced restoration after the digital impression. The provisional restoration and customized abutments were prepared with the optical impression taken on the same day of implant surgery. Moreover, the final prosthesis was fabricated with the digital scan while utilizing the same customized abutment from the provisional restoration. During the data acquisition step, stl data of customized abutments, previously scanned at the time of provisional restoration delivery, were imported and automatically aligned with digital impression data using an 'A.I. abutment matching algorithm' the intraoral scanner software. By using this algorithm, it was possible to obtain the subgingival margin without the gingival retraction or abutment removal. Using the digital intraoral scanner's advanced functions, the operator could shorten the total treatment time. So that both the patient and the clinician could experience convenient and effective treatment, and it was possible to manufacture a prosthesis with predictability.

• Journal of Periodontal and Implant Science
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• v.51 no.6
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• pp.398-408
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• 2021

Purpose: In this study, we aimed to evaluate the clinical validity of the modified tunneling technique using minimal soft tissue harvesting and volume-stable collagen matrix in the anterior mandible. Methods: In total, 27 anterior mandibular teeth and palatal donor sites in 17 patients with ≥1 mm of gingival recession (GR) were analyzed before and after root coverage. For the recipient sites, vertical vestibular incisions were made in the interdental area and a subperiosteal tunnel was created with an elevator. After both sides of the marginal gingiva were tied to one another, a prepared connective tissue graft and volume-stable collagen matrix were inserted through the vestibular vertical incision and were fixed with resorbable suture material. The root coverage results of the recipient site were measured at baseline (T₀), 3 weeks (T₃), 12 weeks (T₁₂), and the latest visit (T_l). For palatal donor sites, a free gingival graft from a pre-decided area avoiding the main trunk of the greater palatine artery was harvested using a prefabricated surgical template at a depth of 2 mm after de-epithelization using a rotating bur. In each patient, the clinical and volumetric changes at the donor sites between T₀ and T₃ were measured. Results: During an average follow-up of 14.5 months, teeth with denuded root lengths of 1-3 mm (n=12), 3-6 mm (n=11), and >6 mm (n=2) achieved root coverage of 97.01%±7.65%, 86.70%±5.66%, and 82.53%±1.39%, respectively. Miller classification I (n=12), II (n=10), and III (n=3) teeth showed mean coverage rates of 97.01%±7.65%, 86.91%±5.90%, and 83.19%±1.62%, respectively. At the donor sites, an average defect depth of 1.41 mm (70.5%) recovered in 3 weeks, and the wounds were epithelized completely in all cases. Conclusions: The modified tunneling technique in this study is a promising treatment modality for overcoming GR in the anterior mandible.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.2
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• pp.165-173
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• 2024

Restoring lost teeth is very important in terms of both function and aesthetics. If tooth loss occurs in the posterior region and the loss of support is persistent, it may cause a gradual shift in the position of the mandible and a change in occlusion. This clinical case attempted to restore support for the posterior teeth with a fixed prosthesis using implants in a patient whose opposing teeth were erupted and the occlusal plane collapsed due to long-term loss of the maxillary left posterior teeth and mandibular right first molars. To correct the occlusal plane of remaining dentition, wax-up of maxillary left posterior teeth was duplicated with acrylic resin and placed on maxilla. Surgical template for implant placement were fabricated using digital technology. After the support of the posterior teeth was restored with the placement of the implant, stable occlusion with temporary restorations was observed for a sufficient time. Afterwards, monolithic zirconia prosthesis was placed on the patient to ensure functional and aesthetic improvement.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.2
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• pp.136-142
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• 2009

Bone density in the recipient implant site seems to be an important factor for long term success of endosseous implants. Preoperative evaluation of bone density is very helpful to assist the clinician with the treatment planning of implant therapy. Accurate information on bone density will help the surgeon identify suitable implant sites, thereby improving the success rate of the procedure. Purpose; The aim of this study was to evaluate a correlation between bone density measured preoperatively with computerized tomography and histologically measured bone density by bone biopsy. Patients and methods; Twenty seven patients were selected. All the patients were in good health, with no systemic disorder and additional bone graft. Preoperatively the patients underwent CT scanning to evaluate Houmsfield Unit(HU). Each patients wore a surgical template for implant placement. During surgery 2mm in diameter and 6mm in length specimens were taken. Histomorphometric analysis was performed using digitalized image analysis software Axiovision 4.3. Also, the Resonance frequency analysis(RFA) and insertion torque values were recorded. Results; The highest histomorphometric values was found in the posterior mandible $32.3{\pm}3.8$, followed by $29.9{\pm}2.6$ for the posterior maxilla, $29.4{\pm}2.6$ for the anterior maxilla, $28.6{\pm}2.3$ for the anterior mandible(p=0.214). The hounsfield unit was $989.2{\pm}258.1$ in the posterior mandible, $845.0{\pm}241.5$ in the anterior maxilla, $744.5{\pm}92.6$ in the anterior mandible, $697.3{\pm}136.9$ in the posterior maxilla(p=0.045). This results may suggest that there are strong correlation between the histomorphometric values and hounsfield unit(r=0.760, p<0.05). The RF measurements were $81.9{\pm}2.4$ ISQ in the posterior mandible, $79.0{\pm}1.4$ ISQ in the anterior mandible, $78.3{\pm}4.6$ ISQ in the posterior maxilla, $76.5{\pm}5.0$ ISQ in the anterior maxilla(p=0.048). The insertion torque values was $43.2{\pm}4.2\;Ncm$ in the posterior mandible, $42.0{\pm}0.0\;Ncm$ in the anterior mandible, $41.3{\pm}4.1\;Ncm$ in the posterior maxilla, $40.8{\pm}3.8\;Ncm$ in the anterior maxilla(p=0.612). This results may suggest that there are statistical significance between the hounsfield unit and the insertion torque values(r=0.494, p<0.05), the histomorphometric values and the insertion torque values(r=0.689, p<0.05). But there was no correlation between histomorphometric values and ISQ. There was no statistical significance in age and gender effect on parameters. Conclusions; There was significant correlations between bone density and implant stability parameters. The bone density measurements using preoperative CT may help clinicians to predict primary stability before implant insertion, which is associated with implant survival rates.

• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.4
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• pp.280-289
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• 2018

Purpose: The purpose of this randomized clinical trial is to determine whether implant length and the crown-to-implant (C/I) ratio influence implant stability and peri-implant marginal bone loss (MBL). Materials and Methods: 46 patients with single tooth missing in the posterior molar region of the mandible were included in this study. 19 implants (CMI IS-III $active^{(R)}$ long implant) of 5.0 mm diameter and 10 mm length were installed for the control group, while 27 implants (CMI IS-III $active^{(R)}$ short implant) of 5.5 mm diameter and 6.6, 7.3 or 8.5 mm length were placed for the experimental group. Each implant was inserted and immediately loaded using the digitally pre-fabricated surgical template and provisional restoration. The CAD-CAM monolithic zirconia crown was fabricated at 3 months after the surgery as a definitive restoration. The ISQ value and the MBL was measured at 48 weeks after the surgery. The correlation between the C/I ratio, MBL, and secondary implant stability was analyzed. Results: Successful results in terms of ISQ and MBL were achieved with both groups. There was no significant difference between the groups in terms of ISQ values and MBL at 48 weeks after the surgery (P > 0.05). No significant correlation was found between the C/I ratio and secondary stability as well as the C/I ratio and the MBL (P > 0.05). Conclusion: The influence of C/I ratio in both groups was not shown on the stability nor the marginal bone loss in implants supporting single crown of the mandible. Short implant could be a preferable alternative option in the reduced bone height mandible under the limited condition despite its higher C/I ratio.