First-principles calculations and Raman scattering evidence for local symmetry lowering in rhombohedral ilmenite: temperature- and pressure-dependent studies.

ATiO3-type materials may exist in two different crystalline forms: the perovskite and ilmenite. While many papers have devoted their attention to evaluating the structural properties of the perovskite phase, the structural stability of the ilmenite one still remains unsolved. Here, we present our results based on the lattice dynamics and first-principles calculations (density functional theory) of the CdTiO3 ilmenite phase, which are confronted with experimental data obtained through micro Raman spectroscopy that is a very good tool to probe the local crystal structure. Additional Raman bands, which are not foreseen from group-theory for the ilmenite rhombohedral structure, appeared in both low temperature (under vacuum condition) and high-pressure (at room temperature) spectra. The behavior can be explained by considering the local loss of inversion symmetry operation which reduces the overall space group from [Formula: see text] ([Formula: see text]) to [Formula: see text] ([Formula: see text]). Our results can also be extended to other ilmenite-type compositions.

Mini-Implants for Mandibular Overdentures: Cost-Effectiveness Analysis alongside a Randomized Trial.

Mandibular overdentures retained by 2 conventional implants have been considered the standard of care for complete edentulism, according to the McGill and York consensuses. However, many patients refuse this treatment modality due to the associated costs and postsurgical discomfort. Mini-implants have the chance to overcome these limitations due to their potentially lower costs and a relatively uncomplicated surgical technique. This study compared treatment costs and incremental cost-effectiveness following the insertion of mini-implants (2 or 4) or 2 standard-size implants for the retention of mandibular overdentures, by means of a randomized clinical trial. In total, 120 edentulous participants (mean age 59.5 ± 8.5 y) were randomly allocated into 3 groups according to treatment received: 4 mini-implants (group 1), 2 mini-implants (group 2), or 2 standard implants (group 3). Treatment costs and outcomes (Oral Health Impact Profile for Edentulous [OHIP-EDENT] and satisfaction with the dentures) were evaluated after 6 mo. Incremental cost-effectiveness ratios (ICERs) were calculated for each intervention in terms of cost per 1-point change in patient outcomes. A 1-way sensitivity analysis was performed considering a 95% confidence interval variation in cost and outcome parameters, represented in tornado diagrams. Overall treatment cost was the lowest for group 2 (average cost: US$318.08), followed by group 1 (US$510.75) and group 3 (US$566.13). Groups did not differ in terms of the length of unscheduled appointments and time spent by participants. In summary, our findings indicate that mandibular overdentures retained by 2 or 4 mini-implants are less costly compared to 2-implant overdentures. Despite the lower costs of overdentures retained by 2 mini-implants, those retained by 4 mini-implants showed further improvement in patient-reported outcomes and reduced costs compared to standard implants ( ClinicalTrials.gov NCT01411683). Knowledge Transfer Statement: This report shows that mini-implant retained overdentures are less costly than overdenture treatment on 2 standard-sized implants. Treatment with 2 mini-implants is an effective procedure to substantially save resources, whereas treatment with 4 mini-implants provides better results from a patient perspective combined with slightly reduced costs compared to the treatment with 2 standard implants. Therefore, mini-implant overdentures may be effective and more accessible than overdentures on 2 standard-size implants for those with limited incomes.

Mini vs. Standard Implants for Mandibular Overdentures: A Randomized Trial.

A mandibular implant-retained overdenture is considered a first-choice treatment for edentulism. However, some aspects limit the use of standard implants-for example, the width of edentulous ridges, chronic diseases, fear, or costs. This randomized trial compared mandibular overdentures retained by 2 or 4 mini-implants with standard implants, considering oral health-related quality of life (OHRQoL), patient satisfaction, and complications such as lost implant. In sum, 120 edentulous men and women (mean age, 59.5 ± 8.5 y) randomly received 4 mini-implants, 2 mini-implants, or 2 standard implants. Participants provided data regarding OHRQoL and satisfaction until 12 mo. Clinical parameters, including implant survival rate, were also recorded. Both 2 and 4 mini-implants led to better OHRQoL, compared with 2 standard implants. Treatment with 4 mini-implants was more satisfying than 2 standard implants, with 2 mini-implants presenting intermediate results. Implant survival rate was 89%, 82%, and 99% for 4 mini-implants, 2 mini-implants, or 2 standard implants, respectively. Overdentures retained by 4 or 2 mini-implants can achieve OHRQoL and satisfaction at least comparable with that of 2 standard implants. However, the survival rate of mini implants is not as high as that of standard implants (ClinicalTrials.gov NCT01411683).

Short-term post-operative pain and discomfort following insertion of mini-implants for retaining mandibular overdentures: a randomized controlled trial.

The retention of removable dentures by mini-implants is a relatively recent treatment modality and may lead to minimal post-operative trauma. This study compared post-operative pain and discomfort following the insertion of mini-implants (two or four) or two standard-size implants for the retention of mandibular overdentures. One hundred and twenty edentulous participants (mean age 59.5 ± 8.5 years) were randomly allocated into three groups according to received treatment: (GI) four mini-implants, (GII) two mini-implants or (GIII) two standard implants. Seven days after implant insertion, patients answered questions (100-mm VAS) relating to pain, swelling, and discomfort with chewing, speech and hygiene, considering their experiences during the 1st and 6th day. Groups were compared by two-way anova (α = 0.05). All participants (GI: 38; GII: 42; GIII: 40) were analysed after 7 days. At the 6th day, GI felt significantly higher pain than GII and GIII. GI also reported more difficulty in performing oral hygiene practices than GIII during the 1st day. There was no significant difference between groups for the other questions and periods. No participant suffered unexpected side effects. The use of four mini-implants induces more intense post-operative pain at the 6th day than the insertion of two mini- or conventional fixtures, as well as more difficult oral hygiene on the 1st day. Clinicaltrials.gov, NCT01411683; FAPESP, 2011/00688-7 and 2011/23347-0.

KRAS and BRAF mutations and MSI status in precursor lesions of colorectal cancer detected by colonoscopy.

Colorectal cancer (CRC) is one of the most frequent cancers worldwide. Adenoma is the main precursor lesion and, recently, the serrated polyps were described as a group of colorectal lesions with malignant potential. The morphologic and biologic characterizations of serrated polyps remain limited. The aim of the present study was to determine the frequency of KRAS and BRAF mutations and microsatellite instability (MSI) in CRC precursor lesions, to evaluate the association between molecular, pathologic and morphologic alterations in precursor lesions and to compare with the alterations detected in CRC. A series of 342 precursor lesions were removed from 155 patients during colonoscopy. After morphologic classification, molecular analysis was performed in 103 precursor lesions, and their genetic profile compared with 47 sporadic CRCs. Adenomas were the main precursor lesions (70.2%). Among the serrated polyps, the main precursor lesion was hyperplastic polyps (HPs) (82.4%), followed by sessile serrated adenomas (12.7%) and traditional serrated adenomas (2.0%). KRAS mutations were detected in 13.6% of the precursor lesions, namely in adenomas and in HPs, but in no serrated adenoma. BRAF mutations were found in 9 (8.7%) precursor lesions, mainly associated with serrated polyps and absent in adenomas (P<0.001). High MSI (MSI-H) was absent in precursor lesions. In the 47 CCR cases, 46.8% exhibited KRAS mutation, 6.5% BRAF mutations and 10.6% MSI-H. This study confirms the role of KRAS and BRAF mutations in CRC carcinogenesis, a crucial step in implementing CRC screening strategies.

A randomised trial of a simplified method for complete denture fabrication: patient perception and quality.

Complete denture fabrication involves a series of complex technical procedures. Nevertheless, simplified methods may be as effective as conventional ones albeit the lesser use of time and resources, without disadvantage for the patient. This study compared a simplified method for complete denture fabrication to a conventional protocol in terms of oral health-related quality of life (OHRQoL), patient satisfaction and denture quality. Forty-two edentulous patients requesting treatment with complete dentures were randomly allocated into two study groups. Group S received dentures fabricated by a simplified method and Group C received conventionally fabricated dentures. Before interventions and after three and 6 months following insertion, OHRQoL and patient satisfaction were analysed by specific instruments. A prosthodontist assessed denture quality 3 months after delivery. Groups presented no difference for OHRQoL, denture quality and general satisfaction. Differences regarding patient satisfaction with some aspects of the dentures were found after 3 months (S > C), but were insignificant at 6 months. It was concluded that the simplified method is able to produce dentures of a quality comparable to those produced by the conventional method, influencing OHRQoL and patient satisfaction similarly.

A randomised trial on simplified and conventional methods for complete denture fabrication: masticatory performance and ability.

OBJECTIVES: To compare a simplified method to a conventional protocol for complete denture fabrication regarding masticatory performance and ability. METHODS: A sample was formed by edentulous patients requesting treatment with maxillary and mandibular complete dentures. Participants were randomly divided into two groups: Group S, which received dentures fabricated by a simplified method, and Group C (n=21 each), which received conventionally fabricated dentures. After three months following insertion, masticatory performance was evaluated by a colorimetric assay based on chewing two capsules as test food during twenty and forty cycles. Masticatory ability was assessed by a questionnaire with binary answers and a single question answered by means of a 0-10 scale. A third group (DN) formed by seventeen dentate volunteers served as an external comparator. Groups were compared by statistical tests suitable for data distribution (α=0.05). RESULTS: Thirty-nine participants were assessed for three months (twenty from Group C and nineteen from Group S). Groups C and S presented similar masticatory performance which corresponded to approximately 30% of Group DN. Results for masticatory ability showed similarity between S and C, regardless of the assessment method, although an isolate questionnaire item showed more favourable results for the first group. CONCLUSIONS: The simplified method for complete denture fabrication is able to restore masticatory function to a level comparable to a conventional protocol, both physiologically and according to patient's perceptions. CLINICAL SIGNIFICANCE: Although masticatory function is impaired by the loss of natural teeth and dentures can restore only a fraction of such function, patients can benefit from a simplified protocol for complete denture fabrication to the same extent they would by conventional techniques.