Analysis of Satisfaction Levels in Completely Edentulous Patients Treated with Different Configurations of Implant Supported Rosthesis.

PURPOSE: The aim of this study is to evaluate and compare patient satisfaction levels in edentulous patients treated with different configurations of implant supported prosthesis. Also, the effect of previous prosthesis experience before implant treatment on patient satisfaction was investigated. MATERIALS AND METHODS: A study population of 142 patients was identified. Patients seperated into four treatment types. Group 1 comprised 43 patients treated with implant supported overdenture for mandible and conventional complete denture for maxilla while group 2 comprised 32 patients treated with implant supported overdentures for maxilla and mandible. Group 3 comprised 26 patients treated implant supported overdenture for mandible and fixed prosthesis for maxilla. Group 4 comprised 41 patients treated with implant supported maxillomandibular fixed restorations. A questionnaire consisting of specific issues about masticatory performance, pronunciation, comfort, social ability were used to evaluate treatment outcomes. RESULTS: The patients in group 4 were significantly more satisfied regarding masticatory performance than other treatment modalities. VAS scores of Group 3 and group 4 regarding comfort and social ability were similar while scores of these two groups were significantly higher than that of group 1 and 2. The patients who used conventional removable prosthesis before implant treatment were more satisfied with their implant supported prosthesis regarding social ability.(p=.03) Conclusion: It was found that treatment design of that implant supported fixed prosthesis on maxilla and implant overdenture on mandible provided comparable level of satisfaction with maxillomandibular fixed prosthesis for edentulous patients. Implant supported fixed prosthesis for maxilla and implant supported overdenture for mandible served as a practical alternative to satisfy patients especially in patients with mandibular atrophy who would demand extensive surgeries for maxillomandibular fixed prosthesis. Satisfaction level of implant supported overdenture was not superior to conventional prosthesis for maxilla. Previous removable prosthesis experience may influence social comfort of patients.

Is Incisive Papilla a Good Landmark to Predict Clinical Outcomes and the Esthetic Perceptions of Edentulous Patients Treated with Implant-Supported Fixed Prostheses on Maxillae?

Purpose: To investigate the effect of incisive papilla on esthetic ratings and lip support for patients who are treated with implant-supported fixed prostheses on edentulous maxillae. Materials and Methods: A study population of 118 patients with maxillomandibular edentulism was identified. A self-administered questionnaire was used to evaluate treatment outcomes through a patient perspective. Also, clinical factors such as smile line, maxillary resorption, incisive papilla position, and lip support were evaluated. Results: Lip support has a significant effect on the facial esthetic scores of patients, while smile line and incisive papilla localization have not had a proven statistically significant effect on esthetic and facial esthestic scores of patients treated with implant-supported fixed prostheses on maxillae. Conclusion: Although the patients were diagnosed with disadvantageous clinical factors such as crestally localized incisive papilla, they still noted higher esthetic scores with their fixed prostheses. Factors that affect the esthetic perception of patients or their priorities should be investigated more to understand the reasons for patient satisfaction with prostheses.

Stability of dental implants with sandblasted and acid-etched (SLA) and modified (SLActive) surfaces during the osseointegration period.

Background. The surface properties of implants are effective factors for increasing the osseointegration and activity of osteoprogenitor cells. This study compared the stability of dental implants with sandblasted and acid-etched (SLA) and modified surfaces (SLActive) using the resonance frequency analysis (RFA). Methods. In a split-mouth design, 50 dental implants with either SLA surface properties (n=25) or modified (SLActive) surface properties (n=25) were placed in the mandibles of 12 patients with a bilateral posterior edentulous area. Implant stability was measured using RFA (Osstell) at implant placement time and every week for 1, 2, and 3 months before the conventional loading time. Results. One week following the implantation, implant stability increased from 70 to 77.67 for SLA and from 71.67 to 79 for SLActive (P < 0.05). Stability improved each week except in the 4th week in SLActive surface measurements. No significant differences were observed between the groups at 2 and 3 months (P > 0.05). Conclusions. For both implant surfaces, increased stability was observed over time, with no significant differences between the groups.

Evaluation of C. Albicans and S. Mutans adherence on different provisional crown materials.

PURPOSE: Bacterial adhesion on provisional crown materials retained for a long time can influence the duration for which permanent prosthetic restorations can be healthily worn in the oral cavity. The aim of this study was to compare seven different commonly used provisional crown materials with regard to Streptococcus mutans and Candida albicans surface adhesion. MATERIALS AND METHODS: For each group, twenty specimens of the provisional fixed prosthodontic materials TemDent (Schütz), Imident (Imicryl), Tab 2000 (Kerr), Structur Premium (Voco), Systemp (Ivoclar Vivadent), Acrytemp (Zhermack), and Takilon-BBF (Takilon) were prepared (diameter, 10.0 mm; height, 2.0 mm). Surface roughness was assessed by atomic force microscopy. Each group was then divided into 2 subgroups (n=10) according to the microbial suspensions used: S. mutans and C. albicans. The specimens were incubated at 37℃ with S. mutans or C. albicans for seven days. Bacterial adherence on surfaces was assessed using the 2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT) assay. RESULTS: S. mutans showed maximum adhesion to Structur, followed by Systemp, Acrytemp, Takilon, Tab 2000, Imident, and TemDent (P<.05). The highest vital C. albicans adhesion was noted on Takilon, followed by Imident and Tab 2000; the lowest adhesion was noted on Systemp (P<.05). CONCLUSION: The materials showed significant differences in the degree of bacterial adhesion. C. albicans showed higher surface adhesion than S. mutans on provisional crown and fixed partial denture denture materials.

The use of autogeneous mandibular bone block grafts for reconstruction of alveolar defects.

OBJECTIVE: Purpose of this retrospective study was to evaluate outcomes autogenous bone block grafts obtained from mandible for different indications. The healing of the donor and recipient sites in the postoperative period, morbidity and the resorption of the graft were investigated. PATIENTS AND METHODS: Twenty-nine patients grafted with mandibular bone block graft were participated in the present study. Grafting was applied in these patients for three indications; reconstruction of alveolar cleft, lateral crest augmentation before dental implantation and sinus floor augmentation. All operations were performed under local anesthesia and in some cases sedation was used as well. RESULTS: Minimal exposure of the block graft occurred in three alveolar cleft patients. Secondary epithelization was achieved in all cleft patients with no symptoms of infection. In one patient infection was seen in donor site 1-week after the operation. The region was curetted and antibiotics administrated again. Two patients showed an infection of recipient site, after 4 weeks the grafts were removed. In all the patients, as the screw head became apparent until 1 thread, amount of the resorption were considered <1.5 mm. CONCLUSION: The usage of mandibular block grafts is a simple and effective treatment modality for reconstruction of different types of alveolar defects and it also reduces cost of treatment.

Influence of surface treatments and resin cement selection on bonding to zirconia.

This study aimed to evaluate the surface changes caused in zirconia by different surface treatments and the influence of the surface treatment and cement selection on bonding to zirconia under aging. Sintered zirconia specimens were divided into five groups (n = 31) based on the surface treatment, namely, control, air abrasion, silica coating, laser and air abrasion + laser. After surface treatment, surface roughness and microscope analyses were performed on one specimen of each group. Composite cylinders were then bonded to conditioned ceramics using RelyX U100 (RXU), Clearfil Esthetic Cement (CEC) and Panavia F (PF) (n = 10). After 24 h, the bonded specimens were subjected to thermal cycling (6,000 times), and then, a shear bond strength test was conducted. The roughness values were analysed using Kruskal-Wallis and Mann-Whitney U tests, and the bond strengths were analysed by two-way analysis of variance and Duncan's test. The relationship between the roughness and the bond strength was determined by Spearman's correlation analysis. Specimens subjected to surface treatments were rougher than the control specimen (p < 0.000). However, there were no significant differences between the air abrasion and air abrasion + laser groups and the silica coating and laser groups. Specimens treated with laser showed lower bond strengths irrespective of the resin cement used. CEC and/or PF showed higher bond strengths than RXU for each surface treatment group. No significant relationship was observed between the roughness and the bond strength. The results of this study showed that all the surface treatments, except for laser irradiation, were suitable for treating zirconia ceramics. Cement selection was found to be more important than surface treatment, and phosphate monomer-containing cements were suitable for cementing zirconia.

Evaluation of marginal fit of two all-ceramic copings with two finish lines.

OBJECTIVES: This in-vitro study investigated the marginal fit of two all-ceramic copings with 2 finish line designs. METHODS: Forty machined stainless steel molar die models with two different margin designs (chamfer and rounded shoulder) were prepared. A total of 40 standardized copings were fabricated and divided into 4 groups (n=10 for each finish line-coping material). Coping materials tested were IPS e.max Press and Zirkonzahn; luting agent was Variolink II. Marginal fit was evaluated after cementation with a stereomicroscope (Leica MZ16). Two-way analysis of variance and Tukey-HSD test were performed to assess the influence of each finish line design and ceramic type on the marginal fit of 2 all-ceramic copings (α =.05). RESULTS: Two-way analysis of variance revealed no statistically significant differences for marginal fit relative to finish lines (P=.362) and ceramic types (P=.065). CONCLUSION: Within the limitations of this study, both types of all-ceramic copings demonstrated that the mean marginal fit was considered acceptable for clinical application (⩽120 µm).

Effects of different acids and etching times on the bond strength of glass fiber-reinforced composite root canal posts to composite core material.

OBJECTIVE: To investigate the effects of different acids and etching times on the bond strength of glass fiber-reinforced composite (FRC) posts to composite core material. METHOD AND MATERIALS: Twenty-six FRC posts (FRC Postec Plus) were randomly divided into 13 groups (each n = 2). One group received no surface treatment (control). The posts in the other groups were acid etched with 35% phosphoric acid and 5% and 9.6% hydrofluoric acid gel for four different etching times (30, 60, 120, and 180 seconds). A cylindric polytetrafluoroethylene mold was placed around the treated posts and filled with dual-cure composite core material (MultiCore Flow). All samples were light cured for 60 seconds. After 24 hours of water storage, the specimens were sectioned perpendicularly to the bonded interface under water cooling to obtain 2-mm post-and-core specimens. Eight specimens were made from each group. Push-out tests were performed at a crosshead speed of 0.5 mm/min using a universal testing machine. Data were analyzed by one-way ANOVA followed by the Tukey honestly significant difference test (alpha = .05). RESULTS: The lowest bond strength was observed in the control group (12.51 megapascal [MPa]). No statistical significant difference was observed among group H5-120 (20.31 MPa), group H9-120 (20.55 MPa), or group P-180 (20.57 MPa) (P > .05). These groups demonstrated the highest bond strength values (P < .05). CONCLUSION: For the FRC posts, all acid-etching procedures tested showed significantly increased bond strength when compared with the control group. Acid-etching with 5% hydrofluoric acid and 9.6% hydrofluoric acid for 2 minutes and with 35% phosphoric acid for 3 minutes (groups H5-120, H9-120, and P-180, respectively) demonstrated the highest bond strength values between the FRC post and composite core material. Although the bond strength was increased by prolonged acid etching, the microstructure of the FRC posts might have been damaged.

Evaluation of the topographical surface changes and roughness of zirconia after different surface treatments.

The purpose of this study was to investigate the surface morphology and roughness of zirconia after different surface treatments. Eighty sintered zirconia specimens were divided into four groups (n = 20) according to the surface treatments received: no treatment, erbium:yttrium-aluminum-garnet (Er:YAG) laser irradiation (400 mJ, 10 Hz, 4 W, 100 MPS, distance: 1 mm), tribochemical silica coating with 30 µm aluminum oxide (Al(2)O(3)) modified by silica, and air abrasion with 110 µm Al(2)O(3) particles. After the surface treatments, the surface roughness (Ra in µm) of the specimens was evaluated using a surface texture measuring instrument. Surface morphology of a specimen from each group was evaluated with atomic force microscope (AFM) and scanning electron microscope (SEM) analyses. The surface roughness values were statistically analyzed by the Kruskal-Wallis and Mann-Whitney U tests (p = 0.05). All of the surface treatments produced rougher surfaces than the control group (p < 0.005). While there were no significant differences between the surface roughness of laser and silica groups (p > 0.05). SEM and AFM analyses revealed changes in surface topography after surface treatments, especially in the laser group with the formation of rare pits and in the silica and air abrasion groups with the formation of microretentive grooves. According to the results of the statistical and microscopic analyses, all of the surface treatments can be used for roughening zirconia prior to cementation; however, air abrasion is the most effective surface treatment to obtain micromechanical retention.

The Effect of Framework Design on Stress Distribution in Implant-Supported FPDs: A 3-D FEM Study.

OBJECTIVES: The biomechanical behavior of the superstructure plays an important role in the functional longevity of dental implants. However, information about the influence of framework design on stresses transmitted to the implants and supporting tissues is limited. The purpose of this study was to evaluate the effects of framework designs on stress distribution at the supporting bone and supporting implants. METHODS: In this study, the three-dimensional (3D) finite element stress analysis method was used. Three types of 3D mathematical models simulating three different framework designs for implant-supported 3-unit posterior fixed partial dentures were prepared with supporting structures. Convex (1), concave (2), and conventional (3) pontic framework designs were simulated. A 300-N static vertical occlusal load was applied on the node at the center of occlusal surface of the pontic to calculate the stress distributions. As a second condition, frameworks were directly loaded to evaluate the effect of the framework design clearly. The Solidworks/Cosmosworks structural analysis programs were used for finite element modeling/analysis. RESULTS: The analysis of the von Mises stress values revealed that maximum stress concentrations were located at the loading areas for all models. The pontic side marginal edges of restorations and the necks of implants were other stress concentration regions. There was no clear difference among models when the restorations were loaded at occlusal surfaces. When the veneering porcelain was removed, and load was applied directly to the framework, there was a clear increase in stress concentration with a concave design on supporting implants and bone structure. CONCLUSIONS: The present study showed that the use of a concave design in the pontic frameworks of fixed partial dentures increases the von Mises stress levels on implant abutments and supporting bone structure. However, the veneering porcelain element reduces the effect of the framework and compensates for design weaknesses.

Evaluation of osteoblastic activity around dental implants using bone scintigraphy.

OBJECTIVES: The aim of this study was to evaluate the osteoblastic activity around delay-loaded intraosseous dental implants using nuclear medicine imaging techniques. MATERIAL AND METHODS: Seven totally edentulous patients (two females and five males, between 48 and 57 years of age) were included in the study. Two implants were inserted into mandibular canine regions and removable prostheses were produced after 3 months. Whole-body bone scintigraphies with 20 mCi technetium 99m labelled methylene diphosphonate were taken from the patients before implant insertion, 3 months after implant placement just before the prostheses were made and 1 year after implant placement. Standardized count/pixel (SC/P) rates were calculated for each patient. Preimplantation SC/P values were compared with the 3- and 12-month values. Three-month values were compared with the 12-month values as well. RESULTS: SC/P rates in the third month were significantly higher (P<0.05) than preoperative values and the SC/P rates of the 12th month were significantly lower (P<0.05) than 3-month values. The SC/P rates of the 12th month were relatively higher than first scintigraphies but the difference was insignificant (P>0.05). CONCLUSIONS: Within the limitations of this study, in which delayed loading was applied, we showed that osteoblastic activity persisted more in delay loaded implants than immediate and early loading. After 1 year, there was no cellular activity around two implants and this implied that two implants were sufficient for a total prosthesis.

The effect of thread design on stress distribution in a solid screw implant: a 3D finite element analysis.

The biomechanical behavior of implant thread plays an important role on stresses at implant-bone interface. Information about the effect of different thread profiles upon the bone stresses is limited. The purpose of this study was to evaluate the effects of different implant thread designs on stress distribution characteristics at supporting structures. In this study, three-dimensional (3D) finite element (FE) stress-analysis method was used. Four types of 3D mathematical models simulating four different thread-form configurations for a solid screw implant was prepared with supporting bone structure. V-thread (1), buttress (2), reverse buttress (3), and square thread designs were simulated. A 100-N static axial occlusal load was applied to occlusal surface of abutment to calculate the stress distributions. Solidworks/Cosmosworks structural analysis programs were used for FE modeling/analysis. The analysis of the von Mises stress values revealed that maximum stress concentrations were located at loading areas of implant abutments and cervical cortical bone regions for all models. Stress concentration at cortical bone (18.3 MPa) was higher than spongious bone (13.3 MPa), and concentration of first thread (18 MPa) was higher than other threads (13.3 MPa). It was seen that, while the von Mises stress distribution patterns at different implant thread models were similar, the concentration of compressive stresses were different. The present study showed that the use of different thread form designs did not affect the von Mises concentration at supporting bone structure. However, the compressive stress concentrations differ by various thread profiles.

Effect of pontic framework design on the fracture resistance of implant-supported all-ceramic fixed partial dentures.

OBJECTIVE: The purpose of this study was to compare the fracture resistance of implant-supported all-ceramic fixed partial dentures, which have three different pontic designs. MATERIAL AND METHODS: Two implants were placed in a metal model simulating mandibular left second premolar and mandibular left second molar. Thirty standardized 3-unit all-ceramic fixed partial dentures with biconvex, convex or concave pontic designs were fabricated using IPS e.max system (n=10). Afterwards, specimens were centrally loaded on the pontics until failure with a universal testing machine. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests at 5% significance level. RESULTS: The fracture resistance values of all-ceramic fixed partial dentures designed with biconvex, convex or concave pontics were 349.71, 438.20 and 300.78 N, respectively. There were no statistically significant differences between the fracture resistances of the groups (p>0.05), except for convex and concave groups (p<0.05 and p=0.009, respectively). CONCLUSIONS: Convex design showed the best mechanical properties as demonstrated by the high values of fracture resistance.

Effect of pontic framework design on the fracture resistance of implant-supported all-ceramic fixed partial dentures

OBJECTIVE: The purpose of this study was to compare the fracture resistance of implant-supported all-ceramic fixed partial dentures, which have three different pontic designs. MATERIAL AND METHODS: Two implants were placed in a metal model simulating mandibular left second premolar and mandibular left second molar. Thirty standardized 3-unit all-ceramic fixed partial dentures with biconvex, convex or concave pontic designs were fabricated using IPS e.max system (n=10). Afterwards, specimens were centrally loaded on the pontics until failure with a universal testing machine. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests at 5 percent significance level. RESULTS: The fracture resistance values of all-ceramic fixed partial dentures designed with biconvex, convex or concave pontics were 349.71, 438.20 and 300.78 N, respectively. There were no statistically significant differences between the fracture resistances of the groups (p>0.05), except for convex and concave groups (p<0.05 and p=0.009, respectively). CONCLUSIONS: Convex design showed the best mechanical properties as demonstrated by the high values of fracture resistance.

Occlusal contact changes with removable and bonded retainers in a 1-year retention period.

OBJECTIVE: To test the hypothesis that there is no difference in the number of occlusal contacts in centric occlusion in patients treated with bonded and removable retention procedures and a control group during a 1-year retention period. MATERIALS AND METHODS: Twenty-five patients received a removable Hawley retainer, and 25 patients received maxillary and mandibular bonded retainers. The retainer patients were compared with 20 control subjects with normal occlusions. Silicone-based impression bites were used to record occlusal contacts. Paired-sample t-test, analysis of variance (ANOVA), and Tukey tests were used to evaluate intragroup and intergroup differences. RESULTS: An increased number of occlusal contacts were recorded in total-arch and posterior combined (actual/near) teeth during the retention period as compared with the control group. In the Hawley group, actual and total contacts on the first and second molar and actual contacts on the premolar and canine showed statistically significant increases. In the bonded retainer group, near and total contacts on the first and second molars and premolars showed statistically significant increases. Slight occlusal changes were seen in the control sample during the observation period, presumably from growth and development. ANOVA comparisons of total contacts of anterior and posterior teeth indicated statistically significant differences in the three groups on posterior segments. CONCLUSIONS: The hypothesis is rejected. Both retention procedures allowed relative vertical movement of the posterior teeth, but the number of contacts on the posterior segment was increased more in the bonded retainer group than in the Hawley and control groups at the end of retention.

Bond strength of adhesively luted ceramic discs to different core materials.

The purpose of this in vitro study was to compare the shear bond strengths of resin, glass-ionomer, and ceramic-based core materials to all ceramic discs. Five core materials (Core max, Sankin; Clearfil AP-X, Kuraray; Empress Cosmo, Ivoclar-Vivadent; Photocore, Kuraray; Dyract Extra, Dentsply) were prepared as discs 10 mm in diameter and 2 mm in height according to the manufacturer's instructions. Ten disc specimens per group were prepared, and dentin served as the control. All resin specimens were embedded in autopolymerizing acrylic resin, with one surface facing up. All ceramic discs (IPS Empress I, Ivoclar-Vivadent) 3 mm in diameter and 2 mm in height were prepared and bonded to core specimens with a dual-curing luting resin cement (Variolink II, Vivadent). Specimens were stored in distilled water at 37 degrees C. Shear bond strength of each sample was measured after 24 h using a universal testing machine at a crosshead speed of 0.5 mm/min. The data were analyzed with one-way analysis of variance and Tukey HSD tests (alpha = 0.05). Shear bond strength varied significantly depending on the core material used (p < 0.05). Clearfil AP-X and Photocore showed the highest shear bond strength value while Empress Cosmo provided the lowest (p < 0.05). There were no statistically significant differences among Clearfil AP-X, Photocore, and Core-Max (p > 0.05). And also there were no statistically significant differences between Dyract Extra and the control group (p > 0.05). In vitro shear bond strengths of ceramic discs bonded to resin-based core materials showed higher bond strength values than ceramic-based core material.

Effect of airborne-particle abrasion on retentive strength in overtapered fixed prosthodontic restorations.

OBJECTIVE: To evaluate retentive strength and film thickness of complete metal crowns cemented to overtapered teeth with 3 different cements after the application of airborne-particle abrasion. METHOD AND MATERIALS: Sixty extracted maxillary molar teeth were embedded in autopolymerizing resin. Crowns were prepared with 30-degree overtapered axial walls and a 1-mm shoulder margin using a water-cooled cylindrical airborne-particle abrasion device. Then, 60 complete crowns were made from a nickel-chromium alloy. Teeth and crowns were assigned to 2 groups, 30 to the control group and 30 to the experimental group to undergo airborne-particle abrasion. In the first part of study, 30 teeth from the experimental group were submitted to the silicon-replica technique and their buccolingual cross sections were measured so that cement film thickness could be measured before airborne-particle abrasion. Three measurements using a light microscope were made in 7 regions of each tooth. In the second part of study, complete metal crowns with and without airborne-particle abrasion were distributed into 3 groups with 10 teeth each to be cemented with zinc phosphate, polycarboxylate, or resin-modified glass ionomer. All specimens were subjected to a tensile bond test in an universal testing machine at a crosshead speed of 0.1 mm/min until failure. The results were then evaluated with Student t test at a 5% level of significance. RESULTS: The film thickness showed no statistically significant differences among groups (P > .05). There was a significant difference between the control and experimental groups, with an increase in all 3 cements after airborne-particle abrasion (P < .05). The highest retentive strength in the control group was found with resin-modified glass ionomer (141.4 +/- 56.7 N), but there was no significant difference between the resin-modified glass ionomer (141.4 +/- 56.7 N) and zinc phosphate (121.4 +/- 24.2 N) (P > .05). Retentive strength of polycarboxylate was the lowest (78.03 +/- 16 N) (P < .05). For the experimental group, the difference among the zinc phosphate (220.5 +/- 83.8 N), polycarboxylate (185.4 +/- 60.8 N), and resin-modified glass ionomer (228.9 +/- 62.4 N) was not statistically significant (P > .05). CONCLUSION: Airborne-particle abrasion had a positive effect on the retention of complete metal crowns when the crowns were cemented with zinc phosphate cement, polycarboxylate cement, or resin-modified glass-ionomer cement.

A 1- to 12-year clinical evaluation of 106 endosseous implants supporting fixed and removable prostheses.

The purpose of this article is to report on the long-term clinical evaluation of patients treated with dental implants. A total of 106 implants were placed in 34 patients and restored with fixed partial dentures and overdentures. The 12-year cumulative implant survival and success rates were 95.2% and 90.2%, respectively. Probing depths around mandibular implants were significantly lower than those around maxillary implants (P < .05). The cumulative implant success rate in nonsmokers was 97.7%, but this dropped to 75.81% in smokers. Also, patients rehabilitated with implant-supported overdentures had more peri-implant tissue inflammation than patients with fixed prostheses.

Occlusal contacts with different retention procedures in 1-year follow-up period.

INTRODUCTION: The aim of this follow-up study was to evaluate the number of contacts in centric occlusion during a 1-year retention period in patients treated with 2 retention procedures and in a control sample. METHODS: Twenty patients received modified wraparound Hawley retainers, and 20 received maxillary Jensen plates with mandibular fixed retainers. These retention patients were compared with a control group of 20 subjects with normal occlusions. Silicone-based impression bites were used to record occlusal contacts. Paired and independent-sample t tests were used to evaluate intragroup and intergroup differences. RESULTS: Contacts increased in the total arch and the posterior combined (actual/near) during the retention period compared with the control group. In the Hawley retainer group, actual contacts on the second molars (P <.05), near contacts on the premolars (P <.05), and total contacts on the first molars (P <.05) and premolars (P <.01) had statistically significant increases. In the maxillary Jensen plate and mandibular fixed lingual retainer group, the number of actual contacts on the posterior segment increased. Actual contacts on the first molars (P <.01), second molars (P <.01), premolars (P <.05), and canines (P <.05), and total contacts on the first (P <.05) and second (P <.05) molars had statistically significant increases. During the observation period, some slight occlusal changes were seen in the control sample, presumably from growth and development. At the end of the study, during the 1-year follow-up period, no statistically significant occlusal contact differences were observed in the 3 groups. CONCLUSIONS: Retention procedures carried out in this study allowed relative vertical movement of the posterior teeth.

Effects of airborne-particle abrasion, sodium hydroxide anodization, and electrical discharge machining on porcelain adherence to cast commercially pure titanium.

The aim of this study was to determine the effect of airborne-particle abrasion (APA), sodium hydroxide anodization (SHA), and electrical discharge machining (EDM) on cast titanium surfaces and titanium-porcelain adhesion. Ninety titanium specimens were cast with pure titanium and the alpha-case layer was removed. Specimens were randomly divided into three groups. Ten specimens from each group were subjected to APA. SHA was applied to the second subgroups, and the remaining specimens were subjected to the EDM. For the control group, 10 specimens were cast using NiCr alloy and subjected to only APA. Surfaces were examined by using scanning electron microscope and a surface profilometer. Three titanium porcelains were fused on the titanium surfaces, whereas NiCr specimens were covered with conventional porcelain. Titanium-porcelain adhesion was characterized by a 3-point bending test. Statistical analysis showed that the porcelain-metal bond strength of the control group was higher than that of the titanium-porcelain system (p < 0.05). There were no significant differences between the bond strengths of titanium groups (p 0.05), except the bond strengths of Noritake Super Porcelain TI-22 groups on which APA and SHA were applied (p < 0.05). SHA and EDM as surface treatment did not improve titanium-porcelain adhesion when compared to APA.