A Predictable Approach to Exquisite Anterior Direct Restorations: the Additive Solution.

A rapidly increasing knowledge of and value in minimally invasive dentistry has shed more light on additive bonding as an ideal solution for esthetic improvement in anterior teeth. Understanding the essentials to performing predictable composite bondings, when indicated and possible, can transform everyday treatment planning to offer enduring, functional, and visually appealing results achieved, most importantly, through additive means. By preserving natural tooth structure and seamlessly blending restorations, additive bonding represents a revolutionary approach to achieving esthetic enhancements while optimizing patient satisfaction. Improvements in the composition of new composite materials have significantly enriched the quality of end-results achievable through layered bonding in the anterior region by providing superior esthetics, durability, and seamless integration with natural teeth. This article summarizes a predictable workflow for layered composite bonding as an approach to achieving enhanced esthetics.

Accelerated Fatigue Resistance of Bonded Composite Resin and Lithium Disilicate Screw-Retained Incisor Crowns with Long and Short Titanium Bases.

This study evaluates the fatigue resistance and failure mode of CAD/CAM composite resin and lithium disilicate-bonded screw-retained incisor crowns with long and short titanium bases. Sixty CAD/CAM implant restorations were fabricated using lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) and composite resin (Block HC, Shofu). The central incisor crowns were bonded to a prefabricated titanium base 6 mm tall (groups: Emax6 and Shofu6; n = 15 each) or a modified abutment 4 mm tall (groups: Emax4 and Shofu4; n = 15 each). The intaglio surface of the restorations was conditioned according to the material and bonded to the titanium abutments/bases using dual-cure cement. All assembled crowns were torqued onto implants and subjected to cyclic isometric loading at the incisal edge along the implant axis. Samples were loaded until fracture. Groups were compared using Kaplan-Meier survival analysis (log rank test at P = .05). The number of mean survived cycles differed significantly, with Emax6 and Emax4 at 48,448 and 43,727 cycles, respectively, and Shofu6 and Shofu4 at 44,124 and 37,620 cycles, respectively. Post hoc tests showed similar fatigue resistance for Emax6, Emax4, and Shofu6. Shofu4 was less resistant than all other groups (P < .03). All restorations survived significantly above physiologic load limits. Lithium disilicate screw-retained incisor crowns can be used with long and short titanium bases, while it is recommended to keep a long titanium base for screw-retained composite resin crowns. The composite resin material required the full height of the abutment for optimal strength but may offer enhanced shock absorption and wear-friendliness when considering function and antagonistic wear.

Luting of inlays, onlays, and overlays with preheated restorative composite resin does not prevent seating accuracy.

PURPOSE: To evaluate in vitro the vertical seating of computer-assisted design/computer-assisted manufacturing (CAD/CAM) composite resin inlays, onlays, and overlays luted with two different composite resins. MATERIALS AND METHODS: Sixty plastic typodont molars were prepared for medium-sized MOD inlays, anatomic onlays, and flat overlays (n = 20); 3-mm thick at the central groove with similar morphology (Cerec biogeneric copy). Restorations were milled using Lava Ultimate blocks, and included standardized hemispherical occlusal concavity for seating measurements with an electromechanic system (force = 30 N). Restorations were luted either with preheated composite resin (Filtek Z100) or dual-cure resin cement (RelyX Ultimate). Seating of restorations was first evaluated at try-in (baseline). Seating was reevaluated after airborne-particle abrasion (Step 1), after seating with luting agent (Step 2), and after light polymerization (Step 3). The Friedman test followed by the Wilcoxon post hoc test were used to compare the seating among steps, and the Kruskal-Wallis test followed by the Mann-Whitney post hoc test were used to compare the seating between luting agents at P < 0.05. RESULTS: Seating differences varied significantly from baseline (P < 0.0125). All restorations seated 3.85 µm (inlays) to 5.45 µm (onlays) deeper after airborne-particle abrasion (Step 1) (P < 0.007). Except for cement-luted inlays, the try-in position (±1 µm) was recovered following unpolymerized luting (Step 2). After polymerization (Step 3), onlays and overlays seated 2.9 to 3.9 µm deeper than during try-in (baseline) using Z100 (P < 0.005), and 7.0 to 7.3 µm deeper using RelyX (P = 0.005). Inlays luted with RelyX seated higher than during try-in (baseline), exactly 7.9 µm after Step 2 (P = 0.005), and 7.7 µm after Step 3 (P = 0.008). Luting with Z100 sustained the seating of inlays with no statistical difference when compared to baseline (P = 0.157). CONCLUSION: Airborne-particle abrasion significantly deepens the seating of CAD/CAM composite resin restorations, but the presence of unpolymerized restorative composite resin luting agent perfectly compensates for this discrepancy. Following polymerization, onlays and overlays seat deeper compared to inlays, especially when using RelyX. The latter, however, resulted in a slightly higher seating of inlays. CLINICAL SIGNIFICANCE: With the least variation compared to baseline seating (try-in), restorative composite resin used as luting agent resulted in the seating of CAD/CAM inlays, onlays, and overlays closer to baseline when compared to dual-cure resin cement.

Optimization of large MOD restorations: Composite resin inlays vs. short fiber-reinforced direct restorations.

OBJECTIVE: To compare mechanical performance and enamel-crack propensity of direct, semi-direct, and CAD/CAM approaches for large MOD composite-resin restorations. METHODS: 45 extracted maxillary molars underwent standardized slot-type preparation (5-mm depth and bucco-palatal width) including immediate dentin sealing (Optibond FL) for the inlays (30 teeth). Short-fiber reinforced composite-resin (EverX Posterior covered by Gradia Direct Posterior) was used for the direct approach, Gradia Direct Posterior for the semi-direct, and Cerasmart composite resin blocks for CAD/CAM inlays. All inlays were adhesively luted with light-curing composite-resin (preheated Gradia Direct Posterior). Shrinkage-induced enamel cracks were tracked by transillumination photography. Cyclic axial isometric chewing (5-Hz) was simulated, starting with a load of 200N (5000 cycles), followed by stages of 400, 600, 800, 1000, 1200, and 1400N (maximum 30,000 cycles each) until fracture or to a maximum of 185,000 cycles. Survived specimens were subjected to cyclic-load-to-failure test at 30-degree angle on the palatal cusp. RESULTS: Only small shrinkage-induced cracks were found in 47% of the direct restorations compared to 7% and 13% of semi-direct and CAD/CAM inlays, respectively. Survival to accelerated fatigue was similar for all three groups (Kaplan-Meier p>.05) and ranged between 87% (direct) and 93% (semi-direct and CAD/CAM). Cyclic-load-to-failure tests did not yield significant differences either (Life Table analysis, p>.05) with median values of 1675N for CAD/CAM inlays, 1775N for fiber-reinforced direct restorations and 1900N for semi-direct inlays. SIGNIFICANCE: All three restorative techniques yielded excellent mechanical performance above physiological masticatory loads. Direct restorations performed as good as inlays when a short-fiber reinforced composite-resin base was used.

A Prediction Model for Functional Outcomes in Spinal Cord Disorder Patients Using Gaussian Process Regression.

Predicting the functional outcomes of spinal cord disorder patients after medical treatments, such as a surgical operation, has always been of great interest. Accurate posttreatment prediction is especially beneficial for clinicians, patients, care givers, and therapists. This paper introduces a prediction method for postoperative functional outcomes by a novel use of Gaussian process regression. The proposed method specifically considers the restricted value range of the target variables by modeling the Gaussian process based on a truncated Normal distribution, which significantly improves the prediction results. The prediction has been made in assistance with target tracking examinations using a highly portable and inexpensive handgrip device, which greatly contributes to the prediction performance. The proposed method has been validated through a dataset collected from a clinical cohort pilot involving 15 patients with cervical spinal cord disorder. The results show that the proposed method can accurately predict postoperative functional outcomes, Oswestry disability index and target tracking scores, based on the patient's preoperative information with a mean absolute error of 0.079 and 0.014 (out of 1.0), respectively.

Quantitative assessment of hand motor function in cervical spinal disorder patients using target tracking tests.

Cervical spondylotic myelopathy (CSM) is a chronic spinal disorder in the neck region. Its prevalence is growing rapidly in developed nations, creating a need for an objective assessment tool. This article introduces a system for quantifying hand motor function using a handgrip device and target tracking test. In those with CSM, hand motor impairment often interferes with essential daily activities. The analytic method applied machine learning techniques to investigate the efficacy of the system in (1) detecting the presence of impairments in hand motor function, (2) estimating the perceived motor deficits of CSM patients using the Oswestry Disability Index (ODI), and (3) detecting changes in physical condition after surgery, all of which were performed while ensuring test-retest reliability. The results based on a pilot data set collected from 30 patients with CSM and 30 nondisabled control subjects produced a c-statistic of 0.89 for the detection of impairments, Pearson r of 0.76 with p < 0.001 for the estimation of ODI, and a c-statistic of 0.82 for responsiveness. These results validate the use of the presented system as a means to provide objective and accurate assessment of the level of impairment and surgical outcomes.

Use of multivariate linear regression and support vector regression to predict functional outcome after surgery for cervical spondylotic myelopathy.

This study introduces the use of multivariate linear regression (MLR) and support vector regression (SVR) models to predict postoperative outcomes in a cohort of patients who underwent surgery for cervical spondylotic myelopathy (CSM). Currently, predicting outcomes after surgery for CSM remains a challenge. We recruited patients who had a diagnosis of CSM and required decompressive surgery with or without fusion. Fine motor function was tested preoperatively and postoperatively with a handgrip-based tracking device that has been previously validated, yielding mean absolute accuracy (MAA) results for two tracking tasks (sinusoidal and step). All patients completed Oswestry disability index (ODI) and modified Japanese Orthopaedic Association questionnaires preoperatively and postoperatively. Preoperative data was utilized in MLR and SVR models to predict postoperative ODI. Predictions were compared to the actual ODI scores with the coefficient of determination (R(2)) and mean absolute difference (MAD). From this, 20 patients met the inclusion criteria and completed follow-up at least 3 months after surgery. With the MLR model, a combination of the preoperative ODI score, preoperative MAA (step function), and symptom duration yielded the best prediction of postoperative ODI (R(2)=0.452; MAD=0.0887; p=1.17 × 10(-3)). With the SVR model, a combination of preoperative ODI score, preoperative MAA (sinusoidal function), and symptom duration yielded the best prediction of postoperative ODI (R(2)=0.932; MAD=0.0283; p=5.73 × 10(-12)). The SVR model was more accurate than the MLR model. The SVR can be used preoperatively in risk/benefit analysis and the decision to operate.

Utilization of a novel digital measurement tool for quantitative assessment of upper extremity motor dexterity: a controlled pilot study.

BACKGROUND: The current methods of assessing motor function rely primarily on the clinician's judgment of the patient's physical examination and the patient's self-administered surveys. Recently, computerized handgrip tools have been designed as an objective method to quantify upper-extremity motor function. This pilot study explores the use of the MediSens handgrip as a potential clinical tool for objectively assessing the motor function of the hand. METHODS: Eleven patients with cervical spondylotic myelopathy (CSM) were followed for three months. Eighteen age-matched healthy participants were followed for two months. The neuromotor function and the patient-perceived motor function of these patients were assessed with the MediSens device and the Oswestry Disability Index respectively. The MediSens device utilized a target tracking test to investigate the neuromotor capacity of the participants. The mean absolute error (MAE) between the target curve and the curve tracing achieved by the participants was used as the assessment metric. The patients' adjusted MediSens MAE scores were then compared to the controls. The CSM patients were further classified as either "functional" or "nonfunctional" in order to validate the system's responsiveness. Finally, the correlation between the MediSens MAE score and the ODI score was investigated. RESULTS: The control participants had lower MediSens MAE scores of 8.09%±1.60%, while the cervical spinal disorder patients had greater MediSens MAE scores of 11.24%±6.29%. Following surgery, the functional CSM patients had an average MediSens MAE score of 7.13%±1.60%, while the nonfunctional CSM patients had an average score of 12.41%±6.32%. The MediSens MAE and the ODI scores showed a statistically significant correlation (r=-0.341, p<1.14×10⁻5). A Bland-Altman plot was then used to validate the agreement between the two scores. Furthermore, the percentage improvement of the the two scores after receiving the surgical intervention showed a significant correlation (r=-0.723, p<0.04). CONCLUSIONS: The MediSens handgrip device is capable of identifying patients with impaired motor function of the hand. The MediSens handgrip scores correlate with the ODI scores and may serve as an objective alternative for assessing motor function of the hand.