Biomechanical variables affect peri-implant bone loss in implant-supported fixed complete dentures: A methodological and prospective study.

PURPOSE: Implant-supported fixed complete dentures (IFCD) experience failures and complications related to biological and technical risk factors. This study investigated the effect of biomechanical variables of IFCD on 1-year peri-implant bone loss at the buccal, palatal/lingual, mesial, and distal implant sides. A new method was used to measure the geometric biomechanical variables of IFCD using cone beam computed tomography (CBCT). METHODS: The study sample consisted of 246 external hexagon implants supporting 48 hybrid IFCD in 44 patients. CBCT images obtained immediately (T0) and 1 year (T1) after prosthesis installation were used to measure the support polygon area, clinical crown/implant (C/I) ratio (vertical lever), anteroposterior power and resistance arms, anterior and posterior cantilevers (horizontal levers), and peri-implant bone remodeling (T1-T0). Data were analyzed using multilevel multivariable models. RESULTS: The average total bone loss in the mandible and maxilla were 0.88 mm, with a loss of 0.62 mm in the mandible and 1.08 mm in the maxilla. The C/I ratio had a significant effect on bone loss on the mesial, distal, and palatal/lingual sides (P <.05). The anterior cantilever had a protective effect on the lingual side of the anterior implant. No effect on bone loss was found for the support polygon area, posterior cantilever, resistance arm, or power arm (P >.05). CONCLUSIONS: The results suggest that the C/I ratio and anterior cantilever in IFCD affect peri-implant bone loss according to the implant side and position in the arch.

Self-Medication Profile of Adult Patients with Temporomandibular Disorders in Southeast Brazil.

Background: Patients with temporomandibular disorder (TMD) often have orofacial pain and may use medication without professional prescription. Self-medication and inappropriate drug intake may cause serious health problems. This cross-sectional study evaluated the self-medication profile of TMD patients, the most used medications and their effect, and the relation between self-medication and socioeconomic factors. Methods: A non-representative sample (n=358) consisted of consecutive adult patients seeking TMD treatment in specialized referral centers for orofacial pain of two universities in São Paulo city, Brazil. A standardized questionnaire was used to collect the study variables before the TMD treatment: self-medication history, TMD pain intensity, sex, age, ethnicity, marital status, schooling and socioeconomic levels. Data were analyzed by descriptive statistics, chi-square test, and logistic regression models at the 0.05 significance level. Results: Almost 60% of 358 TMD patients reported self-medication. Patients with severe TMD were 4.7 times more likely to self-medicate when compared to patients with low TMD intensity (O=5.7; 95% CI=2.4; 13.3; P=0.043), as well as female patients were 30% more likely to self-medicate compared to male patients (OR=2.3; 95% CI=1.1; 5.1; P<0.001). The other independent variables were not associated with self-medication. The frequencies of moderate and severe TMD in women were larger than in those in men (P<0.001). Analgesics and anti-inflammatory drugs were the most used medications. Regarding medication efficacy, 82% of patients reported some improvement after use, but 9% reported side-effect sickness. Conclusion: Self-medication is common among TMD patients attending specialized clinics, and this inappropriate practice is more likely to occur in women and in patients with severe signs and symptoms of TMD.

Mandibular Overdenture Retained by Telescopic Crowns and Ball Attachments on Semierupted Premolars.

This clinical report describes the oral rehabilitation with a mandibular overdenture retained by telescopic crowns and ball attachments on semierupted permanent teeth with a 5-year follow-up. A female patient used an old complete denture in the maxilla and was willing to extract her remaining mandibular teeth to have new dentures. The treatment included preservation of semierupted premolars because of the high surgical risk for mandibular fracture and paresthesia, a new maxillary complete denture, and a mandibular overdenture supported by combined telescopic crowns and ball attachments. The prosthetic rehabilitation restored function and esthetics with high patient satisfaction after 5 years in function.

Radiographic changes of trabecular bone density after loading of implant-supported complete dentures: A 3-year prospective study.

BACKGROUND: Bone tissues may undergo remodeling under functional mechanical stimuli. PURPOSE: This prospective study on implant-supported fixed complete dentures (IFCDs) evaluated the radiographic trabecular bone changes in density by means of gray levels and texture analysis variables after up to 3-year loading. MATERIALS AND METHODS: The sample consisted of digital periapical radiographs of 63 distal implants of hybrid IFCDs installed in 30 patients (22 women, mean age of 62 ± 7.8 years). Digital periapical radiographs were taken after prosthesis installation, and 1 and 3 years after IFCD loading. Longitudinal images of each implant were superimposed, and the same regions of interest were selected for measurement of gray levels statistics (mean gray levels, SD, and coefficient of variation [CV]) and texture parameters (correlation, contrast, entropy, and angular second moment). Data were analyzed by mixed regression models. RESULTS: Mean gray levels increased for 1 year (P < .05), for 3 years (P < .01) and for maximum bite force (P < .01). The interaction between bruxism and time in 1 year was significant (P < .01) for a decrease in CV. No significant effect of texture analysis variables was found (P > .05). CONCLUSIONS: The results suggest an increase of radiographic bone density as measured by an increase in mean gray levels and a decrease in CV in IFCD distal implants up to 3 years of loading.

Duration and sequence of muscular activation in dentate individuals and complete denture wearers during simulation of activities of daily living.

Occlusal support may influence muscular function during complex motor tasks. This study evaluated the duration and sequence of muscular activation of masticatory (temporal, masseter), postural head/neck (sternocleidomastoid, trapezius), postural trunk (rectus abdominis, paravertebrals), and low extremity strength (rectus femoris, gastrocnemius) muscles during simulation of activities of daily living (ADL) in edentulous women wearing complete dentures (n = 10) and in dentate women (n = 10). Electromyographic activity was recorded during tests of stand-up/sit down in the Chair, sit up/lie down in the Bed and lift/lower Bags. Occlusal support (dentures) had a significant effect on duration of muscular activation in the Chair Test: the masseter muscle activated longer with dentures during the standing movement. The masseter and sternocleidomastoid muscles showed significant alteration in their order of activation in non-denture-wearing women. For the Bed Test, dentures had significant effect for the gastrocnemius during the sitting-up phase and for the rectus abdominis during the lying-down movement. For the Bag Test, head/neck muscles were activated in a different order as a function of occlusal support. Anticipation of activation of the paravertebral muscles, rectus abdominis, and gastrocnemius was observed in dentate women compared with denture wearers. These findings suggest that occlusal support influences electromyographic activity of some muscles during simulation of ADL.

Risk factor model of mechanical complications in implant-supported fixed complete dentures: A prospective cohort study.

OBJECTIVES: This prospective cohort study estimated the effect of technical and clinical factors on mechanical complications in implant-supported fixed complete dentures (IFCDs). The patient's perception of the impact of oral rehabilitation on quality of life was assessed. MATERIAL AND METHODS: A non-probabilistic sample consisted of 88 consecutive patients treated with 94 screw-retained, metal-acrylic IFCDs. Data collection included sociodemographic variables, presence and intensity of bruxism, maximal occlusal force, opposing arch, design of the metallic framework, distribution of occlusal contacts, and quality of life (OHIP-14). IFCD-level data were analyzed using Kaplan-Meier survival analysis and Cox regression model. Quality of life data were analyzed by paired Student t test. RESULTS: During a mean follow-up of 35.1 ± 18.3 months, 16/94 IFCDs (17%) had repairable mechanical complications because of loosening/fracture of artificial teeth (n = 15) and screw loosening (n = 1). Framework design (retention pins <4 mm) was a significant risk factor for complications (HR = 11.038; p = 0.027) when adjusted for sex. Mechanical complications were not associated with sex, body mass index, thickness of the acrylic resin veneering, type of opposing arch, distribution of occlusal contacts and force, protrusion interference, presence/intensity of bruxism or maximal occlusal force. OHIP-14 total scores decreased after IFCD treatment for both patients with or without complications. CONCLUSIONS: Within the limitations of this study, the results suggest that clinical success is associated to framework design with retention pins equal or longer than 4 mm. Quality of life improved with IFCD treatment, even in patients with mechanical complications.

Stresses in Implant-Supported Fixed Complete Dentures with Different Screw-Tightening Sequences and Torque Application Modes.

PURPOSE: To compare the effects of different screw-tightening sequences and torque applications on stresses in implant-supported fixed complete dentures supported by five abutments. MATERIALS AND METHODS: Strain gauges fixed to the abutments were used to test the sequences 2-4-3-1-5; 1-2-3-4-5; 3-2-4-1-5; and 2-5-4-1-3 with direct 10-Ncm torque or progressive torque (5 + 10 Ncm). Data were analyzed using analysis of variance and standardized effect size. RESULTS: No effects of tightening sequence or torque application were found except for the sequence 3-2-4-1-5 and some small to moderate effect sizes. CONCLUSION: Screw-tightening sequences and torque application modes have only a marginal effect on residual stresses.

Primary and Secondary Stability of Single Short Implants.

PURPOSE: This prospective cohort study assessed the effect of bone quality on the primary and secondary stability of single short implants placed in the posterior region. MATERIALS AND METHODS: A total of 39 short implants (4.1 × 6-mm long) were placed in the posterior region of the maxilla or mandible in 18 patients. Bone quality was classified into type I, II, III, or IV as assessed intrasurgically. Primary implant stability was measured with insertion torque, damping capacity (PTV values), and resonance frequency analysis (ISQ values). Secondary stability was measured by ISQ and PTV at abutment installation. Data were analyzed by using repeated-measures ANOVA and Tukey's test, Kruskall-Wallis test, and Spearman correlation tests. RESULTS: Implants placed in bone type IV had significant lower insertion torque and ISQ values as well as higher PTV values than in bone types I to II (P < 0.05). The mean ISQ values were higher at abutment installation than at implant placement (P < 0.05), regardless the bone type. The assessment methods of implant stability showed a moderate correlation. CONCLUSIONS: Bone quality influences both the primary and secondary stability of single short implants in the posterior region.

Integridade na pesquisa e ética na publicação / Integrity in research and ethics in publication

As exigências de produção intelectual com base nas publicações científicas constituem mecanismos de pressão sobre pesquisadores, docentes e discentes de programas de pós-graduação, uma vez que os indicadores de qualidade acadêmica estão atualmente atrelados à produção bibliográfica tanto no Brasil quanto no exterior. Nesse contexto, tornam-se cada vez mais necessárias políticas editoriais definidas para que o periódico científico exerça seu papel de orientar a comunidade científica sobre boas práticas editoriais e prevenir más condutas no processo de publicação, tais como casos de plágio, fraude, falsificação de dados, duplicidade e segmentação de resultados, autoria indevida, conflito de interesses, etc...

Surface changes in denture soft liners with and without sealer coating following abrasion with mechanical brushing.

AIM: To evaluate the surface alterations of soft liners with or without sealer coating following abrasion with mechanical brushing. METHODS: Thirty specimens were made of a methacrylate- (Coe-Soft) and a siloxane-based material (Ufi-Gel SC), and 15 received two coatings of surface sealer. The specimens were submitted to a mechanical brushing-dentifrice assay under 200g of force at 250 cycles/min. Mechanical brushing was simulated for a period of 1 (1250 cycles) and 6 months (5000 cycles). Surface roughness (Ra parameter) was measured, and scanning electron microscopy (SEM) images were obtained. Ra data were analysed by anova for repeated measures and Bonferroni's test (alpha=0.05). RESULTS: Ra increased from baseline to 6 months regardless of sealer coating. At baseline, only Coe-Soft without sealer had a higher Ra than the other groups. After 1 month, the Ra of Coe-Soft with sealer was three-fold higher than the Ra at baseline; the other groups showed no significant increase of Ra. SEM images showed degradation of the soft liners over time, except for the Ufi-Gel SC with sealer, which displayed minimum alteration of surface texture. CONCLUSION: Sealer coating reduced the surface degradation of the tested soft liners, but the protective effect was more pronounced for the siloxane-based material.

Analysis of the influence of a mandibular advancement device on sleep and sleep bruxism scores by means of the BiteStrip and the Sleep Assessment Questionnaire.

PURPOSE: A before-and-after experimental clinical study was carried out with the objective of evaluating the effect of a mandibular advancement device (MAD; 75% advancement), made of a thermoplastic material, on sleep bruxism (SB) and sleep scores. MATERIALS AND METHODS: After a habituation period of 1 week, SB scores were taken at baseline and after use of the MAD for 30 days. Scores were compared using the newly developed BiteStrip, which registers the number of contractions of the unilateral masseter muscle after a 5-hour period, giving a severity score from 0 to 3 after the registrations. To assess sleep, the Sleep Assessment Questionnaire (SAQ), a screening tool with scores ranging from 0 to 68, was used before and after use of the MAD. Twenty-eight subjects (13 women, 15 men; mean age: 42.9 +/- 12.0 years) with a clinical history of SB and no spontaneous temporomandibular disorder (TMD) pain were selected. The clinical diagnosis of either moderate or severe SB was further confirmed through use of the BiteStrip (scores 2 or 3) at baseline. A 30-day follow-up period was used for evaluation. Both methods were validated against polysomnography. In addition, common signs and symptoms of TMD based on the Research Diagnostic Criteria for Temporomandibular Disorders were also evaluated before and after use to assess the side effects of the MAD. RESULTS: There was a statistically significant improvement in both SB and sleep scores based on the BiteStrip and the SAQ (Wilcoxon signed rank and Student paired t test, P < .05). In the signs and symptoms of TMD, there was a significant reduction in temporomandibular joint sounds as well as in masseter and temporalis tenderness to palpation. None of the SB subjects experienced any breakage of the MAD. CONCLUSION: The MAD had a positive effect on SB and sleep scores, measured by the BiteStrip and the SAQ, respectively, and did not increase any traditional signs and symptoms of TMD in a 30-day evaluation period.

Marginal fit analysis of premachined and castable UCLA abutments.

This study evaluated the fit between implants and premachined and castable UCLA abutments. All plastic specimens were cast using the conventional technique in accordance with the manufacturer's instructions. Five specimens of each experimental group were measured for vertical and horizontal gaps by scanning electronic microscopy (Phillips XL 30 model, Holland). Gold UCLA (vertical gap: 2.15 microm, horizontal gap: 11.30 microm) and castable rotational UCLA (vertical gap: 14.91 microm, horizontal gap: 59.41 microm) groups showed the lowest and highest mean values, respectively (Neodent, Curitiba, Parana, Brazil). In general, the castable UCLA abutments showed poorer marginal fit than the premachined abutments.

Marginal fit analysis of premachined and castable UCLA abutments

This study evaluated the fit between implants and premachined and castable UCLA abutments. All plastic specimens were cast using the conventional technique in accordance with the manufacturer's instructions. Five specimens of each experimental group were measured for vertical and horizontal gaps by scanning electronic microscopy (Phillips XL 30 model, Holland). Gold UCLA (vertical gap: 2.15 μm, horizontal gap: 11.30 μm) and castable rotational UCLA (vertical gap: 14.91 μm, horizontal gap: 59.41 μm) groups showed the lowest and highest mean values, respectively (Neodent, Curitiba, Parana, Brazil). In general, the castable UCLA abutments showed poorer marginal fit than the premachined abutments.

Esse estudo avaliou a adaptacao entre implantes pilares UCLA usinados e fundidos. Todos os corpos de prova de plastico foram fundidos usando tecnica de fundicao convencional de acordo com o fabricante. Cinco corpos de prova foram avaliados em relacao a desadaptacao vertical e horizontal utilizando um Microscopio Eletronico de Varredura. Os grupos UCLA Ouro (desadaptacao vertical: 2.15 μm, horizontal : 11.30 μm) e UCLA rotacional fundido (desadaptacao vertical: 14.91 μm, horizontal: 59.41 μm) mostraram as medias mais baixas e mais altas, respectivamente. De uma maneira geral, os pilares UCLA fundidos mostraram adaptacao menor do que os pilares UCLA usinados.

Maximum occlusal force and medial mandibular flexure in relation to vertical facial pattern: a cross-sectional study.

BACKGROUND: Vertical facial pattern may be related to the direction of pull of the masticatory muscles, yet its effect on occlusal force and elastic deformation of the mandible still is unclear. This study tested whether the variation in vertical facial pattern is related to the variation in maximum occlusal force (MOF) and medial mandibular flexure (MMF) in 51 fully-dentate adults. METHODS: Data from cephalometric analysis according to the method of Ricketts were used to divide the subjects into three groups: Dolichofacial (n = 6), Mesofacial (n = 10) and Brachyfacial (n = 35). Bilateral MOF was measured using a cross-arch force transducer placed in the first molar region. For MMF, impressions of the mandibular occlusal surface were made in rest (R) and in maximum opening (O) positions. The impressions were scanned, and reference points were selected on the occlusal surface of the contralateral first molars. MMF was calculated by subtracting the intermolar distance in O from the intermolar distance in R. Data were analysed by ANCOVA (fixed factors: facial pattern, sex; covariate: body mass index (BMI); alpha = 0.05). RESULTS: No significant difference of MOF or MMF was found among the three facial patterns (P = 0.62 and P = 0.72, respectively). BMI was not a significant covariate for MOF or MMF (P > 0.05). Sex was a significant factor only for MOF (P = 0.007); males had higher MOF values than females. CONCLUSION: These results suggest that MOF and MMF did not vary as a function of vertical facial pattern in this Brazilian sample.

Intra-oral tactile sensation and aging in a community-based population.

BACKGROUND AND AIMS: Intra-oral sensory function plays an important role in swallowing and food intake, yet the impact of aging on oral tactile perception is uncertain. This study examined the effects of age, ethnicity, and gender on tactile perception at specific intra-oral sites in a community-based sample of 372 Mexican-Americans (MAs) and European-Americans (EAs). METHODS: Four levels of air-pressure were delivered to sites on the anterior and posterior thirds of the tongue and on the velum. Intensity judgments for suprathreshold air puffs were obtained with a direct scaling procedure. Data were analyzed by mixed model multivariate repeated measures ANOVA. RESULTS: Mean judgments of intensity, slopes of intensity functions and intraclass correlation coefficients (ICCs) for intensity judgments, indicated that stimuli delivered to the anterior tongue elicited significantly larger and more consistent responding than at the other sites. MAs produced lower mean stimulus intensity judgments for all sites compared to EAs. No significant age-, gender- or ethnic group-related differences were found at any of the sites for the slopes of the intensity functions or for ICCs. CONCLUSIONS: Stimuli are judged more intense at the anterior tongue compared to the posterior tongue or velum and EAs gave higher estimates of intensity than did MAs. However, there are no age-, gender-, or ethnic group-related differences for the repeatability of intensity judgments or the slopes of intensity functions. Intra-oral tactile perception seems to be preserved during aging.