Accuracy of torque controllers on healing abutments in implant dentistry-an in vitro study.

PURPOSE: To evaluate the accuracy of three torque-control devices used on healing abutments in implant prosthodontics. MATERIALS AND METHODS: In this in vitro experiment, three torque controllers, Ankylos friction-based, Straumann spring-based, and Anthogyr pre-calibrated torque control devices were used to tighten the healing abutments of Ankylos and Straumann dental implants to a pre-determined value of 15 Ncm. A digital torque meter (DT), Cedar DID-4A, was used to assess removal torque as a surrogate for the accuracy of the torque controllers to apply a tightening force of 15 Ncm on healing abutments.  One-way analysis of variance (ANOVA) was used to identify differences between each torque controller and the digital torquemeter, a p < 0.05 was considered significant. RESULTS: The torque required to remove the healing abutments was 16.05 ± 0.66 Ncm for the Ankylos ratchet, 12.61 ± 0.90 Ncm for the Straumann ratchet, and 14.37 ± 1.08 Ncm for the Anthogyr torque-control device. Significant statistical differences were observed between Ankylos and the control digital torquemeter (p = 1.84E-8 ; F = 50.3); Anthogyr and control digital torquemeter (p = 0.01; F = 6.79); and Straumann and control digital torquemeter (p = 0.01; F = 141.15). CONCLUSION: Friction-based (Ankylos), spring-based (Straumann), and pre-calibrated (Anthogyr) torque control devices present over-torque and under-torque values when used over healing abutments of Ankylos and Straumann implant systems.

Implant and prosthetic rehabilitation of a patient with mucous membrane pemphigoid.

Mucous membrane pemphigoid (MMP) is an autoimmune condition characterized by subepithelial separation and deposition of autoantibodies and complement along the basement membrane zone. The disease results in the development of vesiculobullous lesions of the mucous membranes and skin. This report discusses the surgical treatment and management and the prosthetic implant rehabilitation of a patient with mucous membrane pemphigoid. The rationale for this treatment was to fabricate a prosthesis that was stable and did not rub against the gingival tissues and that was easily cleaned. The overdenture attachment system used provides more stability than other attachment systems while allowing the prosthesis and abutments to be easily cleaned.

Dentist-laboratory communication and quality assessment of removable prostheses in Oregon: A cross-sectional pilot study.

STATEMENT OF PROBLEM: When fabricating a removable dental prosthesis, it is unclear if the information received by the dental laboratory technician is clear and sufficient. PURPOSE: The purpose of this survey study was to evaluate the dentist's work authorizations for removable prostheses as well as determine common practices used by laboratories during the fabrication of removable prostheses. MATERIAL AND METHODS: A 24-item questionnaire was developed based on previously published questionnaires and incorporating new topics. A public uniform resource locator (URL) survey link was generated and sent to the office of the Oregon Association of Dental Laboratories (OADL). The executive director of the board then sent out the link to 163 participants that included members and nonmembers of the OADL who were still active in the state of Oregon. Two reminder e-mails were sent 2 weeks apart. Study data were collected and managed by using the Research Electronic Data Capture (REDCap) software program. Descriptive statistics were tabulated, and responses displayed as a percentage of the total. RESULTS: From the 163 invited participants, 26 responded to the survey representing a 15.9% response rate. Only 11% of the laboratories stated that they routinely receive work authorizations with clear instructions. All participants stated that they always (62.5%) or frequently (37.5%) design the partial prostheses frameworks. Only 37.5% of the laboratories stated that they usually receive adequately extended and accurate definitive casts to fabricate the framework. Fifty percent of the laboratories stated that they very rarely perform altered cast procedures and 50% indicated that half or more of the removable partial prostheses they fabricate were entirely made of acrylic resin. Most laboratories stated that thermoplastic resin partial dentures were less than 25% of their produced volume of removable prostheses. Only 22% of respondents stated that they usually receive adequate information to complete a denture tooth arrangement and most (78%) dentists do not routinely specify the type of occlusal scheme desired for their complete denture tooth arrangements. In most prostheses (77%), posterior palatal seal was marked by the prescribing dentists rarely or very rarely. CONCLUSIONS: Work authorizations provided by the dentists were less than adequate and left much decision-making to the dental laboratory technician.

Revisiting the linear separability constraint: New implications for theories of human category learning.

While the ability to acquire non-linearly separable (NLS) classifications is well documented in the study of human category learning, the relative ease of learning compared to a linear separable structure is difficult to evaluate without potential confounds. Medin and Schwanenflugel (Journal of Experimental Psychology: Human Learning and Memory, 7, 355-368, 1981) were the first to demonstrate that NLS classifications are not more difficult to acquire than linearly separable ones when structures are equated in terms of within- and between-category similarities. However, their evidence is less sturdy than might be expected due to non-standard methodology and low sample size. We conducted a conceptual replication to clarify the behavioral picture and perform qualitative testing of formal models. The behavioral results not only showed a lack of advantage for the linearly separable (LS) structure, but revealed a stronger finding: the NLS structure was reliably easier to acquire. Differences in the relative ease of NLS learners to master certain items yielded evidence for the existence of distinct learner subgroups, one marked by significantly easier (not harder) learning of exception items. Comparing the qualitative fits of leading computational models to the human learning performance confirmed that a pure prototype account, even with contemporary updates, remains incompatible with the data. However, exemplar models and similarity-based models grounded in sophisticated forms of abstraction-based learning successfully account for the NLS advantage. In sum, evidence against a linear separability constraint is redoubled, and the observed NLS advantage along with behavioral patterns seen at the subgroup and item level provide a valuable basis for comprehensive evaluation of competing theoretical accounts and models.

The use of 3D printing in shared decision making for a juvenile aggressive ossifying fibroma in a pediatric patient.

Juvenile aggressive ossifying fibromas (JAOF) are rare, typically benign pediatric tumors that are locally aggressive and have high recurrence rates. A 7-year old male presented with a palatal mass and a 3D printed model was created and used as a visual aide to highlight the importance of management in terms of functional, cosmetic, and disease-free outcomes with the family. The patient ultimately underwent successful enucleation with final pathology consistent with JAOF. To our knowledge, this is the first description of the use of 3D printing to help in the shared decision-making process for the treatment of this aggressive tumor.

Shark Fin Titanium Hollow Bulb Obturator: A Treatment Concept.

Restoring esthetics and function for patients with maxillectomy defects presents a complex challenge for the clinician. Obturator prostheses are subject to rotational forces during function, allowing movement into the defect. Gaining prosthesis support from endosseous implants can limit the amount of rotation. Xerostomia and impaired tissue healing caused by radiation therapy further complicates the treatment for such patients. Several resilient and rigid obturator design concepts are available for restoration of such defects. This clinical report describes a design concept used to treat a patient with a maxillectomy defect caused by tumor resection secondary to a squamous cell carcinoma.

Digital Relief of the Mental Foramen for a CAD/CAM-Fabricated Mandibular Denture.

Relief of the intaglio surface of a denture base is conventionally performed using thin wax and soft metal foil attached to the master cast. The following report highlights a new relief procedure for the mental foramen using a CT double scan technique on the CAD/CAM dentures fabricated for the patient with paresthesia of the left lower lip and chin during mastication.

An In Vitro Investigation of Veneered Zirconia-Based Restorations Shade Reproducibility.

PURPOSE: To examine the effects of the veneering technique on the shade reproducibility of zirconia-based crowns. MATERIALS AND METHODS: An artificial tooth was prepared with a 1.2 mm heavy chamfer finish line and 8° taper. The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and devided according to the veneering technique into 3 groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. All veneering layers had the same shade (A2). The specimens were cemented onto the testing dies using glass inomer cement. A spectrophotometer was used to measure the shade coordinates (L, C, h, a, b) for a Vita A2 shade tab and for each specimen. Both the CIE Lab (ΔEab ) and the CIE DE2000 (ΔE00 ) color difference formulas were applied to compare the shade tab and the study groups. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results. RESULTS: Means and standard deviations (SDs) of ΔEab were 2.3 ± 1.3 for LV, 3.5 ± 0.8 for OV, and 4.0 ± 0.7 for DV. Means and SDs of ΔE00 were 1.4 ± 0.8 for LV, 2.1 ± 0.5 for OV, and 3.1 ± 0.4 for DV. ΔEab of LV group was significantly lower (p < 0.05) than both OV and DV groups, whereas the difference in ΔEab between OV and DV groups was not significant (p = 0.39). The differences in ΔE00 between all groups were significant (p < 0.05). CONCLUSIONS: LV group was superior to other groups in terms of shade reproducibility. The ΔEab and the ΔE00 values of LV and OV groups were within clinically acceptable ranges; however, the ΔEab and the ΔE00 values of group DV were beyond the clinically acceptable ranges. The ΔE00 formula demonstrated a statistically significant difference between OV and the DV groups, while the ΔEab formula did not. The zirconia veneering technique had a significant influence on the shade reproducibility of zirconia-based crowns.

Veneered Zirconia-Based Restorations Fracture Resistance Analysis.

PURPOSE: To examine the effects of the veneering technique on the fracture resistance of zirconia-based crowns. MATERIALS AND METHODS: An artificial tooth was prepared with a 1.2 mm heavy chamfer finish line and 8° taper. The prepared tooth was scanned using CAD/CAM technology to fabricate 45 cobalt chromium (CoCr) testing dies. One CoCr die was scanned, and 45 zirconia copings were milled and divided according to the veneering technique into three groups of 15 specimens each: layering veneering (LV) using Vita Vm9, overpressing veneering (OV) using Vita Pm9, and digital veneering (DV) using Vita Triluxe forte. The crowns were cemented onto the testing dies using glass ionomer cement. The specimens were thermocycled (3000 cycles, 5° to 55°) then statically loaded (3.7 mm ball, 0.5 mm/min crosshead speed) until failure. Failed crowns were inspected using a magnifier, and failure patterns were identified. One-way ANOVA and multiple comparison Bonferroni tests were applied for statistical analysis of the results. RESULTS: Means and standard deviations of failure loads were 1200 ± 306 N for the LV group, 857 ± 188 N for the OV group, and 638 ± 194 N for the DV group. The differences in failure loads were statistically significant between all groups (p < 0.05). Failure mode was predominantly cohesive for LV and OV groups, whereas it was predominantly adhesive for the DV group. CONCLUSIONS: The LV group was superior to other groups in terms of fracture resistance, while the DV group was inferior to the other groups in the same aspect.

Effect of Experimental Palatal Prosthesis on Voice Onset Time.

PURPOSE: Objective evaluation of a patient's speech is needed in prosthetic dentistry because the prostheses can affect the intelligibility of speech. Measurement of voice onset time is one evaluation method of consonant production used in phonetic science. The purpose of this study was to confirm the influence of a palatal prosthesis on consonant production by measuring voice onset time. MATERIALS AND METHODS: In this study, voice onset time was measured in 10 healthy women (mean age 26.5 years) under two conditions: with and without an experimental palatal prosthesis. In this study, voice onset time of /ta/ and /ka/ were used to determine the effect of wearing a palatal prosthesis; /pa/ was tested as a control, with the null hypothesis that voice onset time of /ta/ and /ka/ would not change when wearing a palatal prosthesis. RESULTS: Medial voice onset time of /pa/, /ta/, and /ka/ syllables without the palatal prosthesis was 22.5 ms, 19.5 ms, and 42.5 ms, whereas that with the palatal prosthesis was 22.5 ms, 23.5 ms, and 55.0 ms. Voice onset times for /ta/ and /ka/ were prolonged when wearing the experimental palatal prosthesis, whereas /pa/ showed no significant difference. CONCLUSION: Consonant production was affected by wearing a palatal prosthesis, and this change in sound was detected by measuring voice onset time.

Solving Nonlinearly Separable Classifications in a Single-Layer Neural Network.

Since the work of Minsky and Papert ( 1969 ), it has been understood that single-layer neural networks cannot solve nonlinearly separable classifications (i.e., XOR). We describe and test a novel divergent autoassociative architecture capable of solving nonlinearly separable classifications with a single layer of weights. The proposed network consists of class-specific linear autoassociators. The power of the model comes from treating classification problems as within-class feature prediction rather than directly optimizing a discriminant function. We show unprecedented learning capabilities for a simple, single-layer network (i.e., solving XOR) and demonstrate that the famous limitation in acquiring nonlinearly separable problems is not just about the need for a hidden layer; it is about the choice between directly predicting classes or learning to classify indirectly by predicting features.

The Effect of Tissue Entrapment on Screw Loosening at the Implant/Abutment Interface of External- and Internal-Connection Implants: An In Vitro Study.

PURPOSE: To compare the removal of torque values of machined implant abutment connections (internal and external) with and without soft tissue entrapment using an in vitro model. MATERIALS AND METHODS: Thirty external- and 30 internal-connection implants were embedded in urethane dimethacrylate. Porcine tissue was prepared and measured to thicknesses of 0.5 and 1.0 mm. Six groups (n = 10) were studied: External- and internal-connection implants with no tissue (control), 0.5, and 1.0 mm of tissue were entrapped at the implant/abutment interface. Abutments were inserted to 20 Ncm for all six groups. Insertion torque values were recorded using a digital torque gauge. All groups were then immersed in 1 M NaOH for 48 hours to dissolve tissue. Subsequent reverse torque measurements were recorded. Mean and standard deviation were determined for each group, and one-way ANOVA and Bonferroni test were used for statistical analysis. RESULTS: All 60 specimens achieved a 20-Ncm insertion torque, despite tissue entrapment. Reverse torque measurements for external connection displayed a statistically significant difference (p < 0.05) between all groups with mean reverse torque values for the control (13.71 ± 1.4 Ncm), 0.5 mm (7.83 ± 2.4 Ncm), and 1.0 mm tissue entrapment (2.29 ± 1.4 Ncm) groups. Some statistically significant differences (p < 0.05) were found between internal-connection groups. In all specimens, tissue did not completely dissolve after 48 hours. CONCLUSIONS: External-connection implants were significantly affected by tissue entrapment; the thicker the tissue, the lower the reverse torque values noted. Internal-connection implants were less affected by tissue entrapment.

Observation versus classification in supervised category learning.

The traditional supervised classification paradigm encourages learners to acquire only the knowledge needed to predict category membership (a discriminative approach). An alternative that aligns with important aspects of real-world concept formation is learning with a broader focus to acquire knowledge of the internal structure of each category (a generative approach). Our work addresses the impact of a particular component of the traditional classification task: the guess-and-correct cycle. We compare classification learning to a supervised observational learning task in which learners are shown labeled examples but make no classification response. The goals of this work sit at two levels: (1) testing for differences in the nature of the category representations that arise from two basic learning modes; and (2) evaluating the generative/discriminative continuum as a theoretical tool for understand learning modes and their outcomes. Specifically, we view the guess-and-correct cycle as consistent with a more discriminative approach and therefore expected it to lead to narrower category knowledge. Across two experiments, the observational mode led to greater sensitivity to distributional properties of features and correlations between features. We conclude that a relatively subtle procedural difference in supervised category learning substantially impacts what learners come to know about the categories. The results demonstrate the value of the generative/discriminative continuum as a tool for advancing the psychology of category learning and also provide a valuable constraint for formal models and associated theories.

Combination lower lip prosthesis retained by an intraoral component.

Patients who have had a partial or full surgical resection of the maxillary or mandibular lip experience difficulties with articulation of speech, swallowing, and salivary control. This is further complicated by significant alterations in facial esthetics and lowered self-esteem. This clinical treatment will describe the fabrication of a two-piece tooth-retained maxillofacial prosthesis. An intraoral retentive portion and an extraoral section restoring lip anatomy were attached by retentive elements. This prosthesis restored the patient's esthetics, oral function, and self-esteem.

Complement Factor I Gene Variant as a Treatable Cause of Recurrent Aseptic Neutrophilic Meningitis: A Case Report.

Mutations in the complement factor I (CFI) gene have previously been identified as causes of recurrent CNS inflammation. We present a case of a 26-year-old man with 18 episodes of recurrent meningitis, who had a variant in CFI(c.859G>A,p.Gly287Arg) not previously associated with neurologic manifestations. He achieved remission with canakinumab, a human monoclonal antibody targeted at interleukin-1 beta.

Category learning in the context of co-presented items.

A series of four studies explore how the presentation of multiple items on each trial of a categorization task affects the course of category learning. In a three-category supervised classification task involving multi-dimensionally varying artificial organism-like stimuli, learners are shown a target plus two context items on every trial, with the context items' category membership explicitly identified. These triads vary in whether one, two, or all three categories are represented. This presentation context can support within-category comparison and/or between-category contrast. The most successful learning occurs when all categories are represented in each trial. This pattern occurs across two different underlying category structures and across variations in learners' prior knowledge of the relationship between the target and context items. These results appear to contrast with some other recent findings and make clear the potential importance of context-based inter-item evaluation in human category learning, which has implications for psychological theory and for real-world learning environments.

Interim prosthetic phase of multidisciplinary management of cleidocranial dysplasia: "the Bronx Approach".

This case report presents treatment of two patients with the usual characteristics of Cleidocranial Dysostosis. A multidisciplinary approach using the disciplines of prosthodontics, orthodontics, and oral surgery was effected. Exfoliation of the patient's deciduous teeth and failure of permanent anterior tooth eruption led to emotional, social, and self-esteem issues in both patients. Due to the psychosocial issues confronting these two patients, esthetics was addressed prior to active intervention with orthodontics and after some surgical intervention. The use of two interim overdenture prostheses with magnetic retention is described.

Effect of engaging abutment position in implant-borne, screw-retained three-unit fixed cantilevered prostheses.

PURPOSE: To investigate the effects of internally connected engaging component position in screw-retained fixed cantilevered prostheses. MATERIALS AND METHODS: Twenty-one three-unit fixed dental prostheses (FDPs) were cast in high-palladium alloy in three groups. In group A, engaging components were incorporated into the units away from the cantilevered segment; proximal units received nonengaging components. In group B, these positions were reversed. Control specimens were fabricated using all nonengaging components. Specimens were attached to internally connected 3.5 (diameter) × 13 mm (length) implants, torqued to 32 Ncm, and embedded into epoxy resin. Specimens were tested in cyclic fatigue with a 2 Hz sine wave and 0.1 min/max load ratio. Load amplitude started at 1.8 N and increased by 1.8 N every 60 cycles until fracture. Log-rank statistic, ANOVA, Spearman's correlation, and LIFETEST procedures were used to evaluate level of statistical significance within the results. RESULTS: In the control group, the mean number of cycles to fracture was 31,205 ± 2639. Mean axial force at fracture was 932 ± 78 N. In group A, these numbers were 38,160 ± 4292 and 1138 ± 128 N, and in group B, 31,810 ± 3408 and 949 ± 101 N. Statistical significance levels for number of cycles to fracture were: Control versus group A, p = 0.0117, and groups A versus B, p = 0.0156 (statistically significant). Control versus group B, p = 0.357 (not statistically significant). Log-rank statistic for the survival curves is greater than would be expected by chance; there was a statistically significant difference between survival curves (p = 0.012). The location and mode of failure were noteworthy (always in the abutment screw). CONCLUSIONS: The position of the engaging component had significant effects on the results. Within the limitations of this investigation, it can be concluded that using an engaging abutment in a screw-retained fixed cantilevered FDP provides a mechanical advantage, and engaging the implant furthest from the cantilever when designing a screw-retained cantilever FDP increased resistance to fracture of the distal abutment screw.

Fatigue testing of laser treated endosseous implants with an internal trilobe connection.

This study investigated the effect of laser treatment on the fatigue resistance of a 3.5-mm diameter implant with an internal trilobe connection. Twenty two implants were embedded into acrylic resin blocks. Half the specimens were used as control group, and the other half were laser treated circumferentially around the 1.5-mm polished collar with argon shielding. Implants were fatigue tested using a step-stress accelerated lifetime test in a servo-hydraulic test machine. Despite the trend pointing towards higher fatigue resistance of laser treated specimens versus controls, step-stress analysis did not determine significant differences in the fatigue lifetimes.

Preventing inert knowledge: Category status promotes spontaneous structure-based retrieval of prior knowledge.

Analogical comparison of 2 provided cases promotes spontaneous analogical transfer by encouraging a more abstract representation of a target principle. This is widely understood as a process of schema abstraction that aids retrieval from memory in the absence of superficial similarity. The category status hypothesis states that if knowledge about a target principle is represented as a relational category, it is easier to activate as a result of categorizing (as opposed to cue-based reminding). To investigate these 2 pathways to spontaneous transfer (schema retrieval vs. categorization), participants were assigned to different study conditions: (a) standard comparison of 2 analogs; (b) standard comparison followed by a second comparison of 2 new analogs; or (c) a guided Category-building task based on a foundation of sequential summarization with additional categorization supports. Experiment 1 showed improved spontaneous transfer in the Category-building task relative to Single-comparison-the gold standard for encouraging spontaneous transfer. Experiment 2 demonstrated that the Category-building task led to more frequent spontaneous structure-based retrieval than either comparison-based task. This suggests that the transfer improvements observed in Experiment 1 are attributable to the Category-building task making superficially dissimilar prior knowledge more accessible. Experiments 3a and 3b tested alternative explanations of this finding and provided evidence that the effectiveness of the Category-building task arises from encouraging the construal of a target principle as a relational category. These findings support categorization as a critical factor in explaining successful spontaneous analogical retrieval and toward instructional approaches that promote portable rather than inert knowledge. (PsycInfo Database Record (c) 2021 APA, all rights reserved).