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.

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.

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.

Tensile bond strength of a one-bottle adhesive system to indirect composites treated with Er:YAG laser, air abrasion, or fluoridric acid.

OBJECTIVE: This in vitro study evaluated the tensile bond strength of Single Bond adhesive system to indirect composite surfaces treated with Er:YAG laser, fluoridric acid, or air abrasion. BACKGROUND DATA: Application of adhesive techniques is well established in restorative dentistry, yet the influence of surface treatments on the bond strength of adhesive systems to indirect composite restorations prior to luting or repair procedures remains unclear. METHODS: Two hundred and ten samples made of three indirect composites (BelleGlass, Sculpture, and Targis) were divided into 21 groups (n = 10) and treated with (1) control (no treatment); (2) silane (RelyX 3M ceramic primer); (3) 10% fluoridric acid; (4) Er:YAG laser; (5) Er:YAG laser + 10% fluoridric acid; (6) air abrasion; and (7) air abrasion + 10% fluoridric acid. Afterwards, silane and Single Bond adhesive system were applied on each treated surface, and a direct composite resin (Z250) cone was built. The prepared specimens were submitted to tensile bond strength test and stereoscopy evaluation to determine the type of failure after rupture. RESULTS: Bond strength mean values were statistically different in function of indirect composite and surface treatment. BelleGlass treated with Er:YAG laser had the highest mean value (22.92 MPa), and Sculpture conditioned with fluoridric acid had the lowest mean (11.88 MPa). Stereoscopy showed a predominant cohesive failure in Targis resin and mixed type for Sculpture and BelleGlass. CONCLUSIONS: These results suggest that Single Bond tensile bond strength improves with Er:YAG laser as a surface treatment compared to fluoridric acid or air abrasion.

Evaluation of the accuracy of 3 transfer techniques for implant-supported prostheses with multiple abutments.

PURPOSE: This study evaluated the deformation of a metallic framework connected to 15 stone casts fabricated using 3 transfer techniques to determine the most accurate impression procedure. MATERIALS AND METHODS: Five stone casts were made from polyether impressions of an epoxy resin master model for each transfer technique. Group 1 samples were created by the direct splinted technique (square transfer copings splinted with carbon steel pins and autopolymerizing acrylic resin, custom tray); group 2 samples were made by the direct nonsplinted technique (square transfer copings, custom tray); and group 3 samples were fabricated using the indirect technique (tapered transfer copings, custom tray). Sixteen strain gauges were fixed on the framework to measure the degree of framework deformation for each stone cast. Pairs of strain gauges placed opposite each other constituted 1 channel to read deformation (half Wheatstone bridge). Deformation readings were collected at the 4 segments between abutments in 4 directions (anterior, posterior, superior, and inferior). Deformation data were analyzed using analysis of variance and the Tukey test at the .05 and .01 levels of significance. RESULTS: Group 1 samples allowed the most accurate reproduction of analog position compared to the samples made using the other techniques. No significant difference was found between the direct nonsplinted (group 2) and indirect (group 3) techniques. DISCUSSION: Although some studies have evaluated transfer techniques with similar methodology, this study demonstrated the most suitable strain gauge setup to record framework deformations in all directions and simultaneously offset the effects of temperature variation. CONCLUSIONS: The direct splinted technique was the most accurate transfer method for multiple abutments compared to direct nonsplinted and indirect techniques.

Intraoral tactile sensitivity in adults with diabetes.

OBJECTIVE: The intraoral tactile sensitivity (ITS) of diabetic and nondiabetic subjects was compared. The effects of age, ethnicity, sex, and intraoral site were considered. RESEARCH DESIGN AND METHODS: The sample comprised 589 participants of the Oral Health: San Antonio Longitudinal Study of Aging. A total of 107 subjects (61.8 +/- 10.0 years; 48 women, 59 men) met American Diabetes Association diagnostic criteria for diabetes and 482 subjects (58.8 +/- 11.1 years; 274 women, 208 men) did not. ITS was assessed with an oral microaesthesiometer with a cross-modality matching procedure. The dependent variable was the slope of the psychophysical function relating physical stimulus intensity (air pressure) and subjects' judgments of stimulus intensity. Data were analyzed using ANOVA for repeated measures with between-subject factors of age, sex, ethnicity, and diabetes and the within-subject factor of intraoral site. RESULTS: Diabetic and nondiabetic subjects showed no significant differences in ITS at any of the three test sites. European Americans demonstrated greater soft-palate sensitivity (mean +/- SD 0.26 +/- 0.15) compared with Mexican Americans (0.24 +/- 0.16; P = 0.046). The three intraoral test sites differed in tactile sensitivity (P < 0.001); posterior tongue (0.33 +/- 0.22) was most sensitive, followed by the soft palate (0.25 +/- 0.15) and the anterior tongue (0.23 +/- 0.13). Potentially confounding factors were not associated with ITS. CONCLUSIONS: Our results suggest that diabetes per se may not influence ITS.

Dietary intake in edentulous subjects with good and poor quality complete dentures.

STATEMENT OF PROBLEM: Previous studies in complete denture wearers evaluated the relationship between diet and measures of chewing, yet only isolated nutrient intake was considered. This limited information makes the assessment of overall diet quality and the planning of interventions difficult. PURPOSE: This study investigated the relationship of complete denture quality to masticatory performance, perceived ability to chew, and diet quality as measured by the Healthy Eating Index (HEI), an overall diet quality index. MATERIAL AND METHOD: The study population comprised 54 complete denture wearers. Data were obtained from clinical examinations, masticatory performance measurements, and 2 non-consecutive 24-hour dietary recalls. (Masticatory performance data were not collected for 9 subjects because of time constraints, patient fatigue, or patient refusal. Statistical analysis showed no significant effect of their absence on the reported findings.) Based on a composite rating scale, subjects were divided into 3 denture quality groups described as good, medium, and poor. The outcome variables were the HEI and its components, plus selected nutrient and non-nutrient intake. Explanatory variables were quality of complete dentures, masticatory performance, and reported chewing ability. Data were analyzed with Kruskal-Wallis tests, Mann-Whitney U-tests, and Fisher exact tests. Because a large number of dietary components were examined, results were considered significant at alpha=.01. RESULTS: Masticatory performance and perceived ability to chew were unrelated to diet quality. The good quality denture group had significantly better masticatory performance than the medium and poor quality groups, but the median HEI scores and dietary intakes were not significantly different among these 3 groups. Milk, vegetable, fruit, and grain intake scores were mainly responsible for the low overall HEI scores. CONCLUSION: In the population evaluated, complete denture quality, food comminution capacity, and perceived chewing ability were not related to diet quality. The majority of subjects had deficient diets regardless of the technical quality of their dentures.