• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.197-204
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• 2010

The purpose of the study was to observe the time serial changes in proximal contact tightness after single crown restoration. Initial proximal contact tightness before crown preparation and after prosthesis restoration were measured repeatedly in 12 subjects. In consequence proximal contact tightness of temporary setting on prosthesis was bigger than contact tightness before initial preparation, contact tightness of the prostheses of 1-2 weeks after the setting was similar to that before the preparation, tightness of 2-4 weeks after the setting showed little change and maintained constant contact tightness.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.687-695
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• 2007

Statement of problem: The proper contact relation between adjacent teeth in each arch plays an important role in the stability and maintenance of the integrity of the dental arches. Proximal contact has been defined as the area of a tooth that is in close association, connection, or touch with an adjacent tooth in the same arch. Purpose: The aim of this study was to develop a digital device for measuring the proximal tooth contact tightness by pulling a thin stainless steel strip (2mm wide, 0.03mm thick) inserted between proximal tooth contact. Material and method: This device consists of measuring part, sensor part, motor part and body part. The stainless steel strip was connected to a stain gauge. The strain gauge was designed to convert the frictional force into a compressive force. This compressive force was detected as a electrical signal and the electrical signal was digitalized by a A/D converter. The digital signals were displayed by a micro-processor. The pulling speed was 8mm/s. Results: For testing reliability of the device in vivo, two healthy young adults (A, B) participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of mandible (subject A) and maxilla (subject B) was measured fifteen times for three days at rest. We double-checked the accuracy of the device with a Universal Testing Machine. Output signals from the Universal Testing Machine and the measuring device were compared. Regression analysis showed high linearity between these two signals. In vivo test, no significant differences were found between measurements. Conclusion: This device has shown to he capable of producing reliable and reproducible results in measuring proximal tooth contact. Therefore, it was considered that this device was appropriate to apply clinically.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.6
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• pp.553-560
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• 2008

STATEMENT OF PROBLEM: Proximal contact plays an important role in the stability and maintenance of the integrity of the dental arches. However, it is difficult to evaluate quantitatively the tightness of proximal tooth contact (TPTC). PURPOSE: The aim of this study was to measure the TPTC in permanent dentition. MATERIAL AND METHODS: Ten young adult volunteers with healthy dentition participated in this experiment. The TPTC between the teeth of both the maxilla and the mandible was measured at rest state by a novel device which records the TPTC by pulling of a stainless steel strip (0.03 mm thick) using the electric motor. One-way ANOVA test was used to compare the values in all measured area. When a statistically significant difference was calculated, Bonferroni correction was applied. Independent samples t-test was used to compare the values in male and female. RESULTS: The lowest TPTC and the highest TPTC was measured between the lower central incisors (0.87 ${\pm}$ 0.20 N), and between the lower left first molar and second molar (1.99 ${\pm}$ 0.68 N), respectively. All TPTC per quadrant demonstrated a similar pattern of a continuous increased gradient in an anterior-posterior direction. There are no significant difference between the maxilla and mandible. CONCLUSION: The TPTC was measured quantitatively by a novel device and decreased progressively in a posterior-anterior direction.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.4
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• pp.425-442
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• 2004

Statement of problem: A difficulty in achieving a passive-fitting prosthesis can be overcome by individual crown restoation of multiple implants. But individualized crown has another difficulty in control of contact tightness and stress distribution. Purpose: This in vitro study is to evaluate the stress distribution and the magnitude in the supporting tissues around Endopore implants with different crown lengths, interproximal contact tightness, and the splinting effects. Material & methods: Three Endopore implants($4.1{\times}9mm$) were placed in the mandibular posterior edentulous area distal to the canine and photoelastic model was made with PL-2 resin(Measurements Group, Raleigh, USA). Restorations were fabricated in two crown lengths: 9, 13 mm. For non-splinted restorations, individual crowns were fabricated on three custom-milled titanium abutments. After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal($8{\mu}m$ shim stock drags without tearing), medium($40{\mu}m$), and heavy($80{\mu}m$). For splinted restorations, 3-unit fixed partial dentures were fabricated. This study was examined under simulated non-loaded and loaded conditions(6.8 kg). Photoelastic stress analysis was carried out to measure the fringe order around the implant supporting structure. Results: 1. When restorations were not splinted, the more interproximal contact tightness was increased among the three implants, the more stress was shown in the cervical region of each implant. When crown length was increased, stresses tended to increase in the apex of implants but there were little differences in stress fringes. 2. When nonsplinted restorations were loaded on the first or third implant, stresses were increased in the apex and cervical region of loaded implant. Regardless of interproximal contact tightness level, stresses were not distributed among the three implants. But with tighter interproximal contact, stresses were increased in the cervical region of loaded first or third implant. 3. When the nonsplinted restorations were not loaded, there were little stresses on the supporting structure of implants, but low level stresses were shown in the splinted restorations even after sectioning and soldering. 4. With splinted restorations, there were little differences in stresses between different crown lengths. When splinted restorations were loaded, stresses were increased slightly on the loaded implant, but relatively even stress distribution occurred among the three implants. Conclusions: Splinting the crowns of adjacent implants is recommended for Endopore implants under the overloading situation.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.3
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• pp.233-243
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• 2012

The aim of this study was to evaluate time serial change of the TPTC(Tightness of Proximal Tooth Contact) between the implant prosthesis and natural tooth at rest state. Thirty-one patients(19 males and 12 females; mean age, 48.2 years) restored with a total 31 single-implant crowns in the left maxillary for 13 single-implant and left mandibular second molars for 18 single-implant crowns, respectively were selected. The TPTC was checked directly after delivery, 1 month after delivery and 6 months after delivery of prothesis at rest state. The TPTC decreased significantly as time goes by both maxilla(p<.01) and mandible(p<.05). The TPTC between the implant prosthesis and natural tooth decreased as time goes by after fixed implant prothesis placement.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.4
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• pp.412-424
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• 2004

Statement of problem: Several prosthetic options are available for the restoration of multiple adjacent implants. A passively fitting prosthesis has been considered a prerequisite for the success and maintenance of osseointegration. Passivity is a particular concern with multiple implants because of documented inaccuracies in the casting and soldering process. One way to avoid this problem is to restore the implants individually, however, the restorations of individual adjacent impants requires careful adjustment of interproximal contacts. Purpose: The purpose of this study was to compare the stress distribution pattern and amount surrounding Bicon implants with individual crowns and splinted restorations. Material and method: A photoelastic model of a human partially edentulous left mandible with 3 Bicon implants($4{\times}11mm$) was fabricated. For non-splinted restorations, individual crowns were fabricated on 3 abutments ($4{\times}0.65mm,\;0^{\circ}$, 2.0 mm post, Bicon Inc., Boston, USA) After the units were cemented, 4 levels of interproximal contact tightness were evaluated: open, ideal ($8{\mu}m$ shim stock drags without tearing), medium($40{\mu}m)$), and heavy($80{\mu}m$). Splinted 3-unit fixed partial dentures were fabricated and cemented to the model. Changes in stress distribution under simulated non-loaded and loaded conditions(7.5, 15, 30 lb) were analyzed with a circular polaricope. Results: 1. Stresses were distributed around the entire body of fin in Bicon implants. 2. Splinted restorations were useful for distribution of stress around implants especially with higher loads. 3. By increasing the contact tightness between the individually restored three implants, the stress increased in the coronal portion of implants. Conclusions: Ideal adjustment of the contact tightness was important to reduce the stresses around individually restored Bicon implants.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.371-379
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• 2008

The aim of this study was to evaluate the tightness of proximal tooth contact(TPTC) using a novel device at rest state on implant prostheses. Ten healthy young adults with class I normal occlusion consented to participate in the study and twenty patients were restored with a total 20 single-implant crowns in the left maxillary and mandibular second molars for 10 single-implant crowns, respectively. Test area were divided by 4 groups. UM describes the contact between the upper natural left first molar and natural second molar; LM the contact between the lower natural left first molar and natural second molar; IUM the contact between the upper natural left first molar and implant second molar and ILM the contact between the lower natural left first molar and implant second molar. The TPTC was measured at rest state in each area. The mean TPTC of the UM, LM, IUM and ILM was 1.48(${\pm}0.44$) N, 1.78(${\pm}0.40$) N, 1.14(${\pm}0.37$) N and 1.30(${\pm}0.32$) N respectively. These results indicate that the TPTC was less between natural tooth and implant prosthesis than between natural teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.1
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• pp.50-58
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• 2000

The purpose of this study was to investigate the causes of food impaction and to explore solutions as well. For this study, 39 patients with food impaction were selected. 77 contact areas in these patients were investigated mobility, tightness of contact area, gingival index, plaque index, attachment loss, alveolar bone loss, proximal caries, marginal ridge distance and occlusal relationships. The results were as follows ; 1. Teeth without distal support were found to be the most frequent site of food impaction (41.6%). Food impaction was found to be more frequent in the upper teeth (65.2%) than the lower teeth (33.8%). 2. Food impaction was found in tight contact cases (71.4%). Alveolar bone loss was not found in the early stage of food impaction (83.1%) 3. The distance between the marginal ridges of food impaction sites (mean=0.48mm) was short-er than that of the control group. (mean=0.77mm) (p<0.001) 4. In 18.2% of the cases, proximal carries were found at the food impaction site. 5. Food impaction affected patient's occlusion with the following frequencies, cusp to marginal ridge relationship (72.7%), cusp to fossa relationship (3.9%) and stepped relationship (23.4%).

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.1
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• pp.27-33
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• 2014

Purpose: The purpose of this study was to investigate the food impaction between implant prostheses and adjacent natural teeth. Materials and methods: For this study, 51 patients with food impaction were selected and investigated mobility, tightness of contact area, gingival index, plaque index, attachment loss, alveolar bone level, proximal caries, marginal ridge distance and occlusal relationships. Results: Food impaction was found in the upper teeth (60.7%) more than the lower teeth (39.2%). Food impaction was occurred on mesial side of implant prostheses (86.2%) more than distal side (13.7%). Food impaction was mostly found in loose or open contact area (94.2%). Food impaction was frequent on stepped relationship between implant and adjacent teeth. Conclusion: Treatment plan should include proper adjacent and antagonistic occlusal plane and occlusal surface, to prevent food impaction, and the plan should include less adjacent tooth mobility with proper tightness between implant prostheses and adjacent teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.2
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• pp.277-295
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• 1997

After clinical adjustment of dental casting restoration, re-polishing procedure is recommanded because the smooth gold sureface is lost. But there is the possibility to get more loose contact than that intended by loss of gold alloy according to the kinds of polishing materials and polishing time. Therefore in this study I polished type II gold alloy with 390gm force, 20,000rpm speed, and 8 kinds of gold alloy polishing materials, fabricated by 4 companies and then measured the amount of loss of gold alloy with Surfcorder SEF-30D and observed alloy surfaces polished by 3 brown rubber points with SEM. The amount of loss of gold alloys polished with 8 kinds of polishing materials and the degree of smoothness of gold alloys according to polishing time and polishing materials were compared. The following results were obtained : 1. When the amount of loss of gold alloys polished with 3 kinds of brown rubber point was compared, Alphalex brown point had the most amount of alloy loss, followed in decreasing order by Shofu brown point and Eveflex brown point. There was statistically significant difference in the amount of alloy loss according to polishing materials. 2. When the amount of loss of gold alloys polished with 5 kinds of green rubber point was compared, Shofu green point had the most amount of alloy loss, followed in decreasing order by Alphaflex green point, Dedeco green clasp polisher, and Eveflex green point. There was statistically significant difference in the amount of alloy loss according to polishing materials except Alphaflex green point and Dedeco green clasp polisher. 3. When the amount of loss of gold alloys polished with all kinds of rubber point was compared, there was no significant difference in Eveflex brown point, Alphaflex green point, and Dedeco green clasp polisher. 4. When average amount of alloy loss per 1 revolution by polishing materials was compared, Alphalex brown point had the greatest value as $0.329{\mu}m$ and Shofu supergreen point had the lowest value as $0.022{\mu}m$. 5. When the degree of sureface smoothness of gold alloy polished with 3 kinds of brown rubber point was compared, In Alphalex brown point surface roughness was completely lost after 20 seconds polishing time, in Shofu brown point 30 seconds, in Eveflex brown point 40 seconds. But in every gold alloys fine scratch formed by rubber points was observed. Based on the results of this study, as rubber polishing materials used in polishing of dental casting restoration after clinical adjustment influenced on the tightness of occlusal or proximal contact, we should make dental casting restoration with minimum error through careful laboratory procedure and form very smooth surface of restoration with tripoli and rouge after use of silicone polishing materials.