• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.125-140
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• 2011

The remnant of temporary cement on the intaglio surface of cast restoration may have a negative effect on the retentive strength of permanent cement. This study was to evaluate the effect of temporary cement cleaning methods on the retentive strength of cementation type implant prostheses. Prefabricated implant abutments - height 5.5mm, diameter 4.5mm, 6 degree axial wall taper with chamfer margins were used. Forty copings-abutment specimens were divided into four groups(each n=10) according to the cleaning methods for temporary cement(Temp-$Bond^{(R)}$) as follows : no temporary cementation(the control group), orange solvent, ultrasonic cleaning, air borne-particle abrasion. After the application of temporary cement and the separation, the cleaning procedure was performed according to the protocol of each group. The specimens were cemented with $Premier^{(R)}$ Implant $Cement^{TM}$. After the permanent cementation, the specimens were subjected to thermocycling and pulled out from the specimens with a universal testing machine at a cross-head speed of 0.5mm/min. After the retentive strength test, all the specimens were cleaned using ultrasonic cleaning, abraded with air borne-particles, and steam-cleaned. Likewise, the specimens were temporarily cemented(Temp-$Bond^{(R)}$ NE), cleaned according to the protocol of each group, cemented with $Premier^{(R)}$ Implant $Cement^{TM}$ and subjected to thermocycling and measurement of their retentive strength. The mean of group with orange solvent were significantly lower than those of other groups(p<0.05). There was no significance between group with ultrasonic cleaning and group with air borne-particle abrasion. Group with ultrasonic cleaning and group with air-particle abrasion were no significance at control group. There was no significance between group cemented with Temp-$Bond^{(R)}$ and group cemented with Temp-$Bond^{(R)}$ NE. Within the limitation of this study, it can be concluded that the temporary cement cleaning method with only orange solvent may have a negative effect on the retentive strength of permanent cement. Ultrasonic cleaning and air borne-particle abrasion methods are recommended for the temporary cement cleaning method on cementation type implant prostheses.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.4
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• pp.371-383
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• 2012

Shaping the root canal system to maintain original canal curvature is essential to clinical success in endodontic treatment. Opposed to most root canals that are curved, endodontic instruments are made from straight metal blanks. They have a tendency of straightening the root canal during preparation and frequently result in procedural errors. A new treatment method to maintain original canal curvature during shaping has been introduced for preventing procedural errors. The aim of this study was to compare the ability of instruments to maintain original canal curvature of continuous rotary system and single file system. Thirty ISO 15, 0.02 taper, Endo Training Blocks(Dentsplay Maillefer) were used. Specimens were assigned to 1 of 3 groups for shaping: specimens in group 1 were shaped with ProFile #20/.06 at the WL. Specimens in group 2 were shaped with Mtwo #35/.04 at the WL. Specimens in group 3 were shaped with WaveOne Primary reciprocating files at the WL after the glide path was achieved with PathFile. Pre- and postinstrumentation digital images were superimposed and processed with Matlab r2010b(The MathWorks Inc, Natick, MA) software to analyze the curvature-radius ratio(CRr), representing canal curvature modification. Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file were analyzed with 1-way ANOVA(P<.05). Data for comparison on the ability of instruments to maintain original canal curvature depending on each Ni-Ti file system were analyzed with independent t-test(P<.05). A statistically significant difference(P<0.05) was noted on each Ni-Ti file. ProFile and WaveOne instrumentations maintained the original canal curvature significantly better(P<0.05) than Mtwo file. There were no significant difference(P>0.05) between continuous rotary system and single file system. Under the conditions of this study, ProFile and WaveOne instruments maintained the original curvature significantly better than Mtwo file and were less modification of the canal curvature compared. There was no significant difference between continuous rotary system and single file system in shaping of simulated canals. As clinical practitioners, it may be advantages to use hybrid approach when root canal shapes depending on the design and usage of Ni-Ti files.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.209-222
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• 2011

Missing anterior teeth can be replaced using any of a number of methods. Patients may choose to replace missing teeth with a prosthesis that is either removable, fixed, or retained with implants. For patients faced with financial, anatomical, and/or esthetic limitations, the edentulous region can be restored successfully and esthetically with a properly designed and fabricated rotational path RPD. The rotational path RPD is a partial removable dental prosthesis that incorporates a curved, arcuate, or variable path of placement allowing one or more of the rigid components of the framework to gain access to and engage an undercut area. The rigid retainer must gain access to the infrabulge portion of the tooth by rotating into place. Either a minor connector or proximal plate provides retention through its intimate contact with a proximal tooth surface. A specially designed dovetails or asymmetric rest seats provides support and embracing effects. Correctly designed and fabricated rotational path RPD can provide improved esthetics, cleanliness, and retention. But rotational path RPDs are technique sensitive since the rotational path RPD has little margin of laboratory error that rigid retainers cannot be adjusted like conventional clasps can, RPD framework must be remade once the retention is lost. The sufficient understanding of the concept for the rotational path RPD is required for clinically successful treatment. This clinical report describes in detail the theoretical, laboratory considerations and the treatment of a patient with an anterior maxillary edentulous area treated by an AP path rotational RPD that had a difficulty in long term maintenance and describes another clinical case in which more reasonable treatment procedures were approached after analyzing the former case.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.4
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• pp.359-370
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• 2012

The endodontically treated tooth is generally restored with post and core, owing to the brittle and the loss of large amount of tooth structure. The purpose of this study was to evaluate the clinical status of fixed prostheses to improve the quality of dental care. In order to assess the clinical status of fixed prostheses, a total of 101 individuals (aged 30-89, 66 women and 35 men loaded with 125 fixed prostheses) who treated in the Department of Prosthodontics, Pusan National University Dental Hospital, between January 1990 to December 2005 were examined. The results of this study were as follows: 1. Length of service of fixed prostheses was $9.7{\pm}3.4$ years (mean), 11.1 years (median). 2. Age and sex of patient was found to have no statistically significant influence on longevity of fixed prostheses (P>.05). 3. Location of fixed prostheses was found to have statistically significant influence on longevity of fixed prostheses (P<.05). The longevity of fixed prostheses was low in anterio-posterior combination region (median:9.2 years). 4. Longevity of fixed prostheses made of base metal ceramic(median:12.0 years) and noble metal ceramic (median:11.3 years) is long (P<.05). 5. Number of units in fixed prostheses was found to have no statistically significant influence on longevity of fixed prostheses (P>.05). 6. Condition of opposing dentition was found to have no statistically significant influence on longevity of fixed prostheses (P>.05). 7. Dental caries, periapical disease, tooth fracture were frequent complications. In 51.9% of the cases, abutment state after removing fixed prostheses was needed to be extracted.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.197-207
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• 2011

The study aimed at examining how different reline resins affect flexural strength and flexural modulus of denture base. A total of 80 specimens ($64{\times}10{\times}3.3$ mm, according to ISO 1567:1999) of heat-polymerized resin, 40 specimens for (Lucitone199(Dentsply Int., NewYork, USA), SR Ivocap(Ivoclar AG, Schaan, Liechtenstein)) respectively, were polymerized according to the manufacturer's instructions and divided into eight groups(n = 10). Control group specimens remained intact. Specimens in the other groups were abraded on both sides to 2 mm thickness, and were relined in 1.3 mm thickness with 3 types of resins (Lucitone199(Dentsply), SR Ivocap(Ivoclar), and Rebase II(Tokuyama Co., Ltd, Tokyo, Japan)). All specimens were preserved in distilled water at $37^{\circ}C$ for 50 hours, and then were subjected to flexural strength testing in a universal testing machine using 3-point loading. A crosshead speed of 5 mm/min was used, and the distance between the supports was 50 mm. Data analyses included one-way analysis of variance(ANOVA) and the Tukey Honestly Significant Difference test (p=.05). Both heat-polymerized resin groups and auto-polymerized resin groups showed statistically low flexural strength and flexural modulus than control groups. Specimens relined with Lucitone 199 showed significantly higher flexural strength and flexural modulus than those relined with SR-Ivocap. Specimens relined with auto-polymerized resin showed significantly lower flexural strength and flexural modulus than those relined with heat-polymerized resin. Relining with heat-polymerized resins showed superior mechanical properties to relining with an auto-polymerized resin. Relining with the same heat-polymerized resin as the denture base does not affect mechanical properties of a denture. Lucitone199 using a compression-mould technique resulted in the highest flexural strength.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.175-184
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• 2011

With a development of implant restoration technique, there are increasing use of computer-guided system for edentulous patients. It was carried out simulated operation based on CT information about patient's bone quantity, quality and anatomical landmark. However, there are some difference between the programmed implant and post-operative implant about it's position. If the deviation was severe, it could happen a failure of 'passive fit' and not suited for path of implant restoration. The aim of this presentation is to evaluate about a degree of deviations between programmed implant and post-operative implant. Five patients treated by 'NobelGuide' system (Nobel Biocare AB, G$\ddot{o}$teborg, Sweden) in Department of Prosthodontics, Inha University were included in this study. The patients were performed CT radiograph taking and intra-oral impression taking at pre-operation. Based on CT images and study model, surgical stent was produced by NobelBiocareTM. To fabricated a pre-operative study model, after connected lab analog to surgical template, accomplished a pre-operative model using type 4 dental stone. At final impression, a post-operative study model was fabricated in the conventional procedures. Each study model was performed CT radiograph taking. Based on CT images, each implant was simulated in three dimensional position using $Procera^{(R)}$ software (Procera Software Clinical Design Premium, version 1.5; Nobel Biocare AB). In 3D simulated model, length and angulation between each implant of both pre- and post-operative implants were measured and recorded about linear and angular deviation between pre-and post-operative implants. A total of 24 implants were included in this study and 58 inter-implant sites between each implant were measured about linear and angular deviations. In the linear deviation a mean deviation of 0.41 mm (range 0~1.7 mm) was reported. In the angular deviation, a mean deviation was $1.99^{\circ}$ (range $0^{\circ}{\sim}6.7^{\circ}$). It appears that the both linear and angular mean deviation value were well acceptable to application of computer-guided implant system.

• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.2
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• pp.161-174
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• 2011

The purpose of this study was to evaluate the effect of ethanol addition on efficacy of two-step total-etch adhesive under over-wet condition by measurement of remaining volatile part (RVP), microtensile bond strength (${\mu}TBS$), and degree of conversion (DC). Two-step total-etch adhesive, Optibond Solo Plus (Kerr, Orange, USA), was used. Experimental groups were divided into 8 groups: Group 1 (only 10 ${\mu}l$ adhesive), Group 2 (mixture of 3 ${\mu}l$ distilled water and 10 ${\mu}l$ adhesive), From Group 3 to Group 8 (mixture of 3 ${\mu}l$ distilled water, 10 ${\mu}l$ adhesive, and ethanol added in 1 ${\mu}l$ increment from 1 ${\mu}l$ to 6 ${\mu}l$). The mixtures were placed on slide glass and evaporated for 10 s, 30 s, and 60 s by air-drying. The weight of RVP was measured by precision weight. Same procedures were performed for ${\mu}TBS$ test and measurement of DC. The condition of mixed solution was observed under light microscope. For RVP weight, the weights of experimental groups except for group 1 decreased with the increase of air-drying time (p<0.05). The DC increased with the increase of air-drying time in only group 5 and 6 (p<0.05). The ${\mu}TBS$ increased with the increase of air-drying time in group only 5, 6, and 7 (p<0.05). The phase separation was examined and water blisters were diminished with the increase of air-drying time in group 5, 6, 7, and 8. Within the limits of this study, ethanol additionally applied to adhesive decreased RVP and increased DC and ${\mu}TBS$ under over-wet condition. It was shown that the addition of ethanol to two-step total-etch adhesive under over-wet condition would remove water and increase the efficacy of adhesive.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.4
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• pp.337-349
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• 2008

Despite an improved bone reactions of Mg-incorporated implants in the animals, little yet has been carried out by the experimental investigations in functional loading conditions. This study investigated the clinical and histologic parameters of osseointegrated Mg-incorporated implants in delayed loading conditions. A total of 36 solid screw implants (diameter 3.75 mm, length 10mm) were placed in the mandibles of 6 beagle dogs. Test groups included 18 Mg-incorporated implants. Turned titanium Implants served as control. Gold crowns were inserted 3 months. Radiographic assessments and stabilitytests were performed at the time of fixture installation, $2^{nd}$ stage surgery, 1 and 3 months after loading. Histological observations and morphometrical measurements were also performed. Of 36 implants, 32 displayed no discernible mobility, corresponding to successful clinical function. There was no statistically significant difference between test implants and controls in marginal bone levels (p=0.413) and RFA values. The mean BIC % in the Mg-implants was $54.4{\pm}20.2%$. The mean BIC % in the turned implant was $48.9{\pm}8.0%$. These differences between the Mg-implant and control implant were not statistically significant (P=0.264). In the limitation of this study, bone-to-implant contact (BIC) and bone area of Mg-incorporated oxidized implant were similar to machine-turned implant. The stability analysis showed no significantly different ISQ values and marginal bone loss between two groups. Considering time-dependent bone responses of Mg-implant, it seems that Mg-implants enhanced bone responses in early loading conditions and osseointegrated similarly to cp Ti implants in delayed loading conditions. However, further investigations are necessary to obtain long-term bone response of the Mg-implant in human.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.86-95
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• 2015

Purpose: The aim of the study was to evaluate the subjective symptoms and clinical signs through the TMD-questionnaire, clinical examination and radiography against the many instrumental performers and to investigate the association between playing instruments and TMDs. Materials and Methods: A total of 803 instrumental performers received TMD-related questionnaire and evaluations of prevalence and disease distribution were performed. Among those who reported at least one symptom of TMD, 70 volunteers visited in clinic then received clinical examination and radiography for diagnosis and evaluations of prevalence and disease distribution were performed. 70 subjects were divided into three groups as woodwind, brass wind, string. Comparative analysis of disease distribution was performed. Results: Among 803 instrumental performers, 610 people (75.97%) were reported to one or more symptoms of TMD. The most frequent symptom was click (29.68%).70 subjects underwent a clinical examination and radiography survey results, the most frequent symptom was a click (29.75%). Most commonly diagnosed disease was a myofacial pain (30.53%).Comparison of the three groups, a significant difference was not observed in the clinical sign. But among subject symptom, muscle pains howed significant differences in accordance with the Group (P = 0.024). During the 70 people who underwent clinical examination, 66 people (94.3%) showed moderate to severe attrition, mild to severe tongue ridging, mild to severe cheek ridging assigns of parafunction. Conclusion: Instrumental performers showed a high prevalence of TMD and the most of the musicians with temporomandibular disorder had bruxism or clenching habits.

• Journal of Dental Rehabilitation and Applied Science
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• v.31 no.2
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• pp.75-85
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• 2015

Purpose: The purpose of this study is to evaluate which FRC-posts were more distinguishable from core. Materials and Methods: Nine extracted single-rooted mandibular premolars with similar lengths (${\pm}0.5 mm$) and widths (${\pm}0.5 mm$) were endodontically treated and obturated. One specimen which the three roots were embedded in a cold mounting resin was made. 3 specimens were made by this method. Post spaces were prepared for the following post system: FRC $Postec^{(R)}$ Plus, MACRO-$LOCK^{TM}$ POST $ILLUSION^{TM}$ $XRO^{(R)}$, $Snowpost^{(R)}$. After three different posts were placed in the roots of a specimen, each three specimens received a direct core build-up: $Luxacore^{(R)}$ Dual A3, $Luxacore^{(R)}$ Dual blue, $Filtek^{TM}$ Z350 A1E. Digital images were taken of the post and core with and without air-blowing. We asked to fifty dentists and fifty dental college students which post was more clearly discriminated from the core. Results: In surveys, when core was $Luxacore^{(R)}$ Dual blue, among three types of posts people more easily discriminated the $Snowpost^{(R)}$ from core. When core was $Luxacore^{(R)}$ Dual A3, among three types of posts people similarly more easily discriminated $Snowpost^{(R)}$ from core. When core was $Filtek^{TM}$ Z350 A1E, among three types of posts people more easily discriminated distinguished MACRO-$LOCK^{TM}$ POST $ILLUSION^{TM}$ $XRO^{(R)}$ post from core. People more easily distinguished MACRO-$LOCK^{TM}$ POST $ILLUSION^{TM}$ $XRO^{(R)}$ post from core when temperature was lowered by air-blowing. Conclusion: Ability to discriminate between FRC-post and core is different according to color contrast. MACRO-$LOCK^{TM}$ POST $ILLUSION^{TM}$ $XRO^{(R)}$ posts are more discriminable when temperature is lowered by air-blowing.