Conventional maxillary denture versus maxillary implant-supported overdenture opposing mandibular implant-supported overdenture: Patient's satisfaction.

OBJECTIVES: This study sought to determine the impact of age, gender, and use of maxillary implant-supported overdenture (UISOD) versus conventional denture (CMD) opposing mandibular implant-supported overdenture (LISOD) and the number of years the patient has used their prosthesis on the ratings of satisfaction. This study aimed to assess the long-term influence of different factors on patients' satisfaction with LISODs needing a maxillary prosthesis, helping dentists choose a treatment pathway that leads to a higher satisfaction rate. MATERIAL AND METHODS: This cross-sectional study included 84 participants. They were treated with LISOD opposing either CMD or UISOD from 2015 to 2020. They were all eligible to participate in the study. An oral health impact profile (OHIP-14) questionnaire was given to each patient and filled out by them. OHIP-14 scores were gathered and went under statistical analysis with PASS-11 software to determine the relationship between patients' satisfaction with the scores. RESULTS: Age and gender had no significant influence on how satisfied patients were. Patients with maxillary overdentures showed more satisfaction than the CMD group (p < .05). Moreover, patients' satisfaction decreased with increasing years of prostheses usage (p < .05). CONCLUSIONS: This study demonstrated that satisfaction is related to the type of maxillary prosthesis (conventional or implant-supported) used opposing LISODs and the number of years the patient had used the prostheses.

Rehabilitation of a patient with amelogenesis imperfecta and severe open bite: A multidisciplinary approach.

Amelogenesis imperfecta (AI) is typically associated with anterior open bite and a number of other dental problems, which require complex treatments such as orthognathic surgery. This case report describes management of a patient with AI and severe open bite via a multidisciplinary approach.

Fracture Strength of Posterior Crowns made of Adoro and Gradia Fiber-reinforced Composites.

Aim: The aim of this study was to assess the fracture strength of posterior crowns made of Adoro and Gradia fiber-reinforced composites (FRCs). Materials and methods: In this in vitro, experimental study, extracted sound 37 maxillary first and second premolars were selected. A celluloid index was taken from teeth and the teeth received crown preparation. Impressions were made and poured. Composite crowns were fabricated of Adoro and Gradia composite resins. After curing, the teeth were immersed in distilled water for 24 hours and thermal cycled for 6,000 cycles between 5 and 55°C. Load was applied at a crosshead speed of 1 mm/minute and the fracture strength was measured. Specimens were inspected under a stereomicroscope to determine the mode of failure. Results: The fracture strength was 1,631.77 N for Gradia and 1,569.84 N for Adoro. The difference between the fracture strength of the two groups was not significant (p > 0.05). The mode of failure was cohesive in composite in 7 specimens and adhesive between composite and fiber in 12 specimens in the Gradia group. In the Adoro group, the mode of failure was cohesive within composite in 11 specimens and adhesive between composite and fiber in 7 specimens. Complete tear of fiber did not occur in any group. Conclusion: The fracture strength of Gradia and Adoro composites is not significantly different. Clinical significance: Cohesive fracture within the fiber did not occur in any case in our study and the mode of failure was adhesive at the fiber-composite interface or cohesive within the composite in most specimens. Keywords: Composite resin, Crown, Gradia, Laboratory.

Effects of incorporation of 2.5 and 5 wt% TiO2 nanotubes on fracture toughness, flexural strength, and microhardness of denture base poly methyl methacrylate (PMMA).

PURPOSE: The aim of this preliminary study was to investigate, for the first time, the effects of addition of titania nanotubes (n-TiO2) to poly methyl methacrylate (PMMA) on mechanical properties of PMMA denture base. MATERIALS AND METHODS: TiO2 nanotubes were prepared using alkaline hydrothermal process. Obtained nanotubes were assessed using FESEM-EDX, XRD, and FT-IR. For 3 experiments of this study (fracture toughness, three-point bending flexural strength, and Vickers microhardness), 135 specimens were prepared according to ISO 20795-1:2013 (n of each experiment=45). For each experiment, PMMA was mixed with 0% (control), 2.5 wt%, and 5 wt% nanotubes. From each TiO2:PMMA ratio, 15 specimens were fabricated for each experiment. Effects of n-TiO2 addition on 3 mechanical properties were assessed using Pearson, ANOVA, and Tukey tests. RESULTS: SEM images of n-TiO2 exhibited the presence of elongated tubular structures. The XRD pattern of synthesized n-TiO2 represented the anatase crystal phase of TiO2. Moderate to very strong significant positive correlations were observed between the concentration of n-TiO2 and each of the 3 physicomechanical properties of PMMA (Pearson's P value ≤.001, correlation coefficient ranging between 0.5 and 0.9). Flexural strength and hardness values of specimens modified with both 2.5 and 5 wt% n-TiO2 were significantly higher than those of control (P≤.001). Fracture toughness of samples reinforced with 5 wt% n-TiO2 (but not those of 2.5% n-TiO2) was higher than control (P=.002). CONCLUSION: Titania nanotubes were successfully introduced for the first time as a means of enhancing the hardness, flexural strength, and fracture toughness of denture base PMMA.

Effect of Repeated Screw Joint Closing and Opening Cycles and Cyclic Loading on Abutment Screw Removal Torque and Screw Thread Morphology: Scanning Electron Microscopy Evaluation.

PURPOSE: To evaluate the effect of repeated screw joint closing and opening cycles and cyclic loading on abutment screw removal torque and screw thread morphology using scanning electron microscopy (SEM). MATERIALS AND METHODS: Three groups (n = 10 in each group) of implant-abutment-abutment screw assemblies were created. There were also 10 extra abutment screws as new screws in group 3. The abutment screws were tightened to 12 Ncm with an electronic torque meter; then they were removed and removal torque values were recorded. This sequence was repeated 5 times for group 1 and 15 times for groups 2 and 3. The same screws in groups 1 and 2 and the new screws in group 3 were then tightened to 12 Ncm; this was also followed by screw tightening to 30 Ncm and retightening to 30 Ncm 15 minutes later. Removal torque measurements were performed after screws were subjected to cyclic loading (0.5 × 106 cycles; 1 Hz; 75 N). Moreover, the surface topography of one screw from each group before and after cyclic loading was evaluated with SEM and compared with an unused screw. RESULTS: All groups exhibited reduced removal torque values in comparison to insertion torque in each cycle. However, there was a steady trend of torque loss in each group. A comparison of the last cycle of the groups before loading showed significantly greater torque loss value in the 15th cycle of groups 2 and 3 compared with the fifth cycle of group 1 (P < .05). Nonetheless, torque loss values after loading were not shown to be significantly different from each other. CONCLUSION: Using a new screw could not significantly increase the value of removal torque. It was concluded that restricting the amount of screw tightening is more important than replacing the screw with a new one when an abutment is definitively placed.

Microleakage Evaluation at Implant-Abutment Interface Using Radiotracer Technique.

OBJECTIVES: Microbial leakage through the implant-abutment (I-A) interface results in bacterial colonization in two-piece implants. The aim of this study was to compare microleakage rates in three types of Replace abutments namely Snappy, GoldAdapt, and customized ceramic using radiotracing. MATERIALS AND METHODS: Three groups, one for each abutment type, of five implants and one positive and one negative control were considered (a total of 17 regular body implants). A torque of 35 N/cm was applied to the abutments. The samples were immersed in thallium 201 radioisotope solution for 24 hours to let the radiotracers leak through the I-A interface. Then, gamma photons received from the radiotracers were counted using a gamma counter device. In the next phase, cyclic fatigue loading process was applied followed by the same steps of immersion in the radioactive solution and photon counting. RESULTS: Rate of microleakage significantly increased (P≤0.05) in all three types of abutments (i.e. Snappy, GoldAdapt, and ceramic) after cyclic loading. No statistically significant differences were observed between abutment types after cyclic loading. CONCLUSIONS: Microleakage significantly increases after cyclic loading in all three Replace abutments (GoldAdapt, Snappy, ceramic). Lowest microleakage before and after cyclic loading was observed in GoldAdapt followed by Snappy and ceramic.

Effect of eugenol-containing and resin endodontic sealers on retention of prefabricated metal posts cemented with zinc phosphate and resin cements.

PURPOSE: The aim of this study was to compare the effects of two endodontic sealers on the retention of posts cemented with zinc phosphate or resin cement. MATERIALS AND METHODS: Crowns of 72 mandibular premolars were removed at the cementoenamel junction. Root canals were prepared and specimens were randomly divided into two groups of 36. In each group, 12 specimens were obturated with gutta percha only; 12 specimens with gutta percha/ZOE sealer and 12 specimens with gutta percha/AH26. In the first group, 10mm Post spaces were prepared with Peeso reamers size 4 and, size 5 stainless steel Paraposts were cemented in with zinc phosphate. In the second group, 10mm Post spaces were prepared with Fiber Lux size 5.5 drills and size 5 Paraposts were cemented with Panavia F2.0. After mounting in resin blocks, posts were pulled out by universal testing machine at 1mm/min and results were analyzed by two-way ANOVA and Dunnett test. RESULTS: Mean forces (in Newtons) required to remove posts cemented with zinc phosphate in canals obturated without sealer, with ZOE, and with AH26 sealers were 270±83, 281±128 and 266±67, respectively; and for posts cemented with Panavia F2.0 were 520±290, 464±212 and 229±108, respectively. Statistical analysis showed that AH26 significantly reduced retention of posts cemented with Panavia F2.0 (p<0.05). CONCLUSION: Different sealers had no significant effect on retention of posts cemented with zinc phosphate. However posts cemented with Panavia F2.0 showed reduced retention in canals obturated with AH26.

Effect of a procedural video CD and study guide on the practical fixed prosthodontic performance of Iranian dental students.

Dental students in programs around the world typically pass preclinical courses before entering the clinic and working on actual patients. Since fixed prosthodontics is a preclinical course that requires a great deal of effort, students may experience a substantial amount of stress that may affect their self-confidence and/or clinical performance. In this study, an instructional video CD (VCD) and study guide depicting the step-by-step procedures involved in a metal-ceramic tooth preparation and provisional crown fabrication was prepared. Students at the Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran, were divided randomly into two groups. Group A students trained as usual with live patients, and Group B students were given a copy of the VCD and study guide following a lecture. The students in Group B were encouraged to read the study guide and watch the VCD after live demonstrations. Then, both groups practiced individually on mannequins. At the end of the course, the students completed a sixteen-item questionnaire about their stress level, self-confidence, and knowledge base. The results showed that the students exposed to the extra media performed significantly better on some practical phases, e.g., laboratory procedures. A moderate, insignificant correlation was detected between exposure to media and decreasing the students' stress and self-esteem. We concluded that supplementary teaching aids such as a VCD and study guide may improve the clinical performance of dental students to some extent, but the live demonstration is still preferred by students.