Despite of technical difficulties, the combination of occlusal projection and densitometric digital analysis may ultimately provide a means of detection of subtle bone loss at the facial and lingual side of dental implant (Oblique occlusal view is more useful for ITI dental implant due to its contour of shoulder as like tulip' flower). In this study, conventional periapical projections of x-ray beam had shown more high sensitivity to detect the bony defects than oblique occlusal projections in alveolar crest obscured by dental implants or not, even if the difference was not statistically significant. Unlike conventional periapical projections, occusal projections combined with densitometric digital analysis technique may provide a means for detection of subtle bone change at the all around of implants without obscuring effect by implant itself. Although the results from this in vitro study were performed under limited circumstances, these results might afford more possibility and versatile modality of diagnosis options to clinician in the implant practice.
Dental Implants* ; Diagnosis ; Pilot Projects* ; Shoulder

This investigation was designed to determine the effectiveness of the posterior occlusal schemes on masticatory activity during mastication in complete denture. Twelve edentulous subjects were selected for this study. All subjects had no past history and no functional abnormality on masticatory system and Tmjoint. And, they had residual ridge of favorable morphology, firm mucosa and Class I skeletal jaw relationship. The masticatory performance was analyzed by means of standard sieve(10, 16, 20, 30sieve), and the electrical activity from selected muscles(Temporalis and Masseter muscle)was recorded simultaneously with electromyography (Bio-Pak system) as the subject masticated test foods (rice, peanut and grm) with four different occlusal schemes. Mandibular movement was, also, measured with Sirognathography(Bio-Pak system). These recordings were performed in immediately, after 1 week and after 2 weeks of insertion of complete denture. The results were as follows; The average masticatory performance of 0-degree artificial teeth was higher than any other artificial teeth. Masticatory performance in denture wearer was affected preferentially by food and artificial occlusal schemes. During chewing, there was a statistical difference of EMG activity between masseter and temporal muscle (p<0.01). Especially, EMG activity of working masticatory muscle was highly affected by food rather than by artificial occlusal schemes. In denture wearer, the velocity of opening was not affected by food, whereas, the velocity of closing was faster in soft food chewing than in hard food chewing. And the amount of vertical displacement was grater in chewing of soft and large bolus than in chewing of hard and small bolus. However, the amount of lateral displacement showed conversely(p<0.05). It was considered that masticatory performance in denture wearer is not affected by the condition of residual ridge, the history of denture wear, the preference, the adaptation to artificial teeth and the total mesiodistal length of artificial posterior teeth.
Dental Restoration Wear ; Denture, Complete* ; Electromyography ; Jaw ; Mastication ; Masticatory Muscles ; Mucous Membrane ; Stomatognathic System ; Temporal Muscle ; Tooth ; Tooth, Artificial

Adherence of Candida albicans(C. albicans) to the surface of a denture is believed to be an initial and essential step in the formation of denture-induced stomatitis. Previous studies have provided enormous infomation on the relationship between composition of palatine gland/parotid saliva and upper denture stomatitis. Relatively little information is available on the correlation between lower denture stomatitis and sublingual-submandibular(SLSM) saliva. The plaque samples were collected from the two sites(100mm2) on the inner surface of lower partial denture corresponding to the stomatitis and healthy region of the lower partial dentures of 12 denture stomatitis patients and 6 normal persons who wore lower partial dentures. The samples were plated to isolate C. albicans on a selective Saboraud's dextrose agar plate and the isolates were identified by germ tube test and gram staining. The subjects were divided into group I (stomatitis with C. albican), group II (lesion without C. albicans), group III (no lesion but C. albicans), and group IV (normal and healthy denture wearer). Individual SLSM saliva (20microgram of protein) was analyzed by SDS-PAGE(SDS-poly-acrylamide gel electrophoresis) with Coomassie brilliant blue and PAS(Periodic Acid Schiff) staining. The salivary proteins separated in the polyacryamide gels were subjected to immunoblot analysis using anti-lactoferrin, anti-sIgA, and anti-secretory component of sIgA. In this study using custom made acrylic denture resin beads(5mm in diameter) coated with stimulated individual SLSM saliva, the binding ability of individual C. albicans strains to the beads was observed. Levels of C. albicans adhered to the acrylic resin beads were determined by measuring the optical density of the bound C. albicans to the beads at 580nm. The results showed that a higher number of C. albicans was observed in the lesion site than health site. The saliva of group I contained more high molecular weight glycoprotein(mucin, MG1) as compared to group II, III, and IV. And lactoferrin and sIgA affected to the binding ability of C. albicans to acylic resin beads. Binding ability of individual C. albicans to the acrylic resin coated with respective individual saliva was found to be greater in group I than the other 3 groups. And when bound cells of C. albicans isolated from individual subject #2 to the saliva coated beads were used, binding ability of subject #2 saliva coated beads was founed to be greater than the other subjects. These results suggested that denture induced stomatitis is related to individual patient's salivary protein composition, especially MG-1. Future studies will be directed toward saliva examination of patients who have general disease and analysis of pellicles formed on prosthesis with respect to oral disease.
Agar ; Candida albicans* ; Candida* ; Denture, Partial ; Dentures* ; Gels ; Glucose ; Glycoproteins* ; Humans ; Immunoglobulin A, Secretory ; Lactoferrin ; Molecular Weight ; Prostheses and Implants ; Saliva ; Salivary Proteins and Peptides ; Stomatitis ; Stomatitis, Denture*

It is a great challenge for dentists to do prosthetic restorations of a patient with reduced occlusal vertical dimension (OVD). Proper determination of the OVD is significant. An 85-year-old male patient came in with missing right maxillary posterior teeth. After diagnostic wax-up, reversible provisional prostheses were used to evaluate the new OVD in the maxilla and mandible. After that, the patient was evaluated clinically based on the criteria of esthetic, phonetic, and OVD. After 8 weeks, teeth with excessive wear were treated with root canal therapy and fiber post and core and irreversible provisional prostheses were done. After 8 weeks of observation period, final restorations with fixed partial dentures and removable partial dentures were made. Throughout the follow-up period of 6 months, no symptoms related with increased OVD and mechanical complications were observed.
Aged, 80 and over ; Dentists ; Denture, Partial, Fixed ; Denture, Partial, Removable ; Follow-Up Studies ; Humans ; Male ; Mandible ; Maxilla ; Porphyrins ; Prostheses and Implants ; Root Canal Therapy ; Tooth ; Vertical Dimension

PURPOSE: The design of the attachment must provide an optimum stress distribution around the implant. In this study, for implant overdentures with a bar/clip attachment or a locator attachment, the stress transmitted to the implant in accordance with the change in the denture base length and the vertical pressure was measured and analyzed. MATERIALS AND METHODS: Test model was created with epoxy resin. The strain gauges made a tight contact with implant surfaces. A universal testing machine was used to exert a vertical pressure on the mandibular implant overdenture and the strain rate of the implants was measured. RESULTS: Means and standard deviations of the maximum micro-deformation rates were determined. 1) Locator attachment: The implants on the working side generally showed higher strain than those on the non-working side. Tensile force was observed on the mesial surface of the implant on the working side, and the compressive force was applied to the buccal surface and on the surfaces of the implant on the non-working side. 2) Bar/clip attachment: The implants on the both non-working and working sides showed high strain; all surfaces except the mesial surface of the implant on the non-working side showed a compressive force. CONCLUSION: To minimize the strain on implants in mandibular implant overdentures, the attachment of the implant should be carefully selected and the denture base should be extended as much as possible.
Denture Bases* ; Denture, Overlay* ; Dentures*

In case of missing of permanent teeth by trauma or innate defect, the decision of treatment modalities and application timing have an important effect on the prognosis of oral rehabilitation. In this case report, interdisciplinary approach between the orthodontic and prosthodontic treatment, the way to re-establish the collapsed occlusal vertical dimension, and implant prosthetic considerations will be discussed. Proper diagnosis on teeth and craniofacial skeleton was made prior to treatment and provisional restorations were used in regard of growth patterns of the patient. Finally, the edentulous areas were restored with fixed implant prostheses. Diagnosis, treatment rationale and prognosis will be discussed thoroughly.
Adolescent* ; Growth and Development ; Humans ; Prognosis ; Prostheses and Implants ; Prosthodontics ; Tooth* ; Vertical Dimension

STATEMENT OF THE PROBLEM: Under anatomical limitations on maxillary posterior region, a poor crown-to root ratio acting on dental implants can result in undesirable stress in surrounding bone, which in turn can cause bone defects and eventual failure of implants. PURPOSE: The purpose is to compare stress distribution due to different crown-root ratio and effect of splinting between natural teeth and implants in maxillary molar area under different loads. MATERIAL AND METHODS: Analysis of stress arising supporting bone of the natural teeth and the implant was made with 3-dimensional finite element method. The model simulated naturel teeth was made with 2nd premolar and 1st molar in the maxillary molar region (Model T). The model simulated implants placed on same positions with two parallel implants of Straumann Dental Implant cemented abutment (Model I). Each model was designed in different crown-root ratio (0.7:1, 1:1, 1.25:1) and set cement type gold crown to make it non-splinted or splinted. After that, 300 N force was loaded to each model in five ways (Load 1: middle of occlusal table, Load 2: middle of buccal cusp, Load 3: middle of lingual cusp, Load 4: horizontal load to buccal cusp of anterior abutment only, Load 5: horizontal load to middle of buccal cusp of each abutment), and stress distribution was analyzed. RESULTS AND CONCLUSION: On all occasions, stress was concentrated at the cervical region of the implant. Under load 1, 2 and 3, stress was not increased even when crown-root ratio increases, but under load 4 and 5, when crown-root ratio increases, stress also increased. There was difference in stress values between natural teeth and implants when crown-root ratio gradually increases; In case of natural teeth, splinting decreased stress under vertical and horizontal loads. In case of implants, splinting decreased stress under vertical loads 1,2 and 3, but increased maximal stress under loads 2 and 3. Under horizontal loads, splinting decreased stress, however the effect of splinting decreased under load 5 than load 4. Furthermore, the stress was increased, when crown-root ratio is 1.25:1. CLINICAL IMPLICATIONS: This limited finite element study suggests that the stress on supporting bone may be increased under non-axial loads and poor crown-root ratio. Under poor crown-root ratio, excessive stress was generated at the cervical region of the implant, and decreased splinting effect for stress distribution, which can be related to clinical failure.
Bicuspid ; Crowns ; Dental Implants ; Finite Element Analysis ; Molar ; Splints ; Tooth

As a material of metal-ceramic prosthesis, nickel as a form of Ni-Cr alloy has been used for many dental prostheses in many cases. However, several problems in use of the alloy have been revealed (ex ; tissue stimulation, skin allergy, hypersensitivity, cytotoxicity and carcinogenecity). Little is known about nickel with respect to the relationship between Ni-prosthesis and gaining of Ni-resistance in oral microorganisms. The present study was undertaken to check wheather use of Ni-prosthesis leads to occurrence of Ni-resistant microorganisms. So this study may suggest the possible relationships between the oral microorganisms and nickel-resistance in oral enviroment. Bacteria were isolated from the gingival crevicular fluid on the patients wearing Ni-Cr prosthesis. The isolated bacteria were tested for their Ni-resistance in nickel containing media at different concentration from 3mM to 110mM. E. coli HB101 was used as control. The Ni-resistant bacteria were isolated and biochemically identified. The Ni-resistant bacteria were tested several biochemical, molecular-biological tests. Performed tests were ; measuring the growth curve, antibiotic test, growth ability test in liquid media, isolation of the chromosome and plasmid, digestion of DNA by restriction enzyme, electrophoresis of chromosome and plasmid DNA, identification of Ni-resistant genes by the DNA hybridization. The results were as follows: 1) The bacteria isolated from gingival crevicular fluid on the patients wearing Ni-Cr alloy prosthesis showed nickel-resistance. 2) The isolated microorganisms grew at nickel containing media of high concentrations (60mM-110mM). 3) Based on the biochemical tests, the isolated microorganisms were identified as Enterococcus faecalis(13 cases), Klebsiella pneumoniae(1 case) and Enterobacter gergoviae(1 case). 4) Enterococcus faecalis expressed not only nickel resistance but also the multi-drug resistanceto several antibiotics ; chloramphenicol, kanamicin, streptomycin, lincomycin, clindamycin. However all strain showed the sensitivity against the tetracycline. 5) DNA hybridization result suggest that there is no homology between the previousely known gene of nickel resistance in Klebsiella pneumoniae and chromosomal DNA Enterococcus faecalis.
Alloys* ; Anti-Bacterial Agents ; Bacteria* ; Chloramphenicol ; Clindamycin ; Dental Prosthesis ; Digestion ; DNA ; Electrophoresis ; Enterobacter ; Enterococcus ; Enterococcus faecalis ; Gingival Crevicular Fluid* ; Humans ; Hypersensitivity ; Klebsiella ; Klebsiella pneumoniae ; Lincomycin ; Nickel ; Plasmids ; Prostheses and Implants* ; Skin ; Streptomycin ; Tetracycline

PURPOSE: The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method. MATERIALS AND METHODS: The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at α=.05. RESULTS: No statistically significant differences in distances among four notches (P>.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly (P < .05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods (P < .05). CONCLUSION: The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.
Denture Bases ; Dentures ; Fungi ; Methods ; Printing, Three-Dimensional ; Sutures

PURPOSE: A novel retentive type of implant prosthesis that does not require the use of cement or screw holes has been introduced; however, there are few reports examining the biomechanical aspects of this novel implant. This study aimed to evaluate the biomechanical features of cementless fixation (CLF) implant prostheses.MATERIALS AND METHODS: The test groups of three variations of CLF implant prostheses and a control group of conventional cement-retained (CR) prosthesis were designed three-dimensionally for finite element analysis. The test groups were divided according to the abutment shape and the relining strategy on the inner surface of the implant crown as follows; resin-air hole-full (RAF), resin-air hole (RA), and resin-no air hole (RNA). The von Mises stress and principal stress were used to evaluate the stress values and distributions of the implant components. Contact open values were calculated to analyze the gap formation of the contact surfaces at the abutment-resin and abutment-implant interfaces. The micro-strain values were evaluated for the surrounding bone.RESULTS: Values reflecting the maximum stress on the abutment were as follows (in MPa): RAF, 25.6; RA, 23.4; RNA, 20.0; and CR, 15.8. The value of gap formation was measured from 0.88 to 1.19 µm at the abutmentresin interface and 24.4 to 24.7 µm at the abutment-implant interface. The strain distribution was similar in all cases.CONCLUSION: CLF had no disadvantages in terms of the biomechanical features compared with conventional CR implant prosthesis and could be successfully applied for implant prosthesis.
Crowns ; Finite Element Analysis ; Prostheses and Implants ; RNA