A Lab-Based Study to Assess the Surface Roughness of Various Investments: An Original Research

Introduction

Surface roughness of the crowns is dependent on the pattern material used for the making as well as the procedure of investing. The study was aimed to examine the impact of various pattern materials and investment procedures on the surface roughness of nickel-chromium alloy raw castings.

Materials and Methods

An in-vitro study was piloted at a tertiary care hospital. Eighty samples of inlay wax and pattern resin were divided equally. They were invested in phosphate-bonded investment material and kept under normal atmospheric pressure as well as invested under a pressure of 3 bars. The surface roughness was calculated with a Profilometer. The values obtained were compared using statistical tools keeping P < 0.05 as significant.

Results

Lowest surface roughness was seen for the wax pattern invested under positive pressure. While the highest was seen for the resin patterns invested at room pressure. A significant variance between the wax 1 and wax 2 (P < 0.01); as well as between the wax 2 vs. Resin 2 specimens (P < 0.01) was noted.

Conclusions

Wax patterns can be suggested as the material and method of choice because they showed the least amount of surface roughness when placed under pressure. Resin patterns when invested under pressure can also be suggested as an alternate as they also exhibited similar surface roughness as that of the wax.

Knowledge and awareness of polycaprolactone and its applications as provisional material in prosthodontic practice: A questionnaire-based survey

Aim

The present study was done to evaluate the knowledge and awareness of different provisional materials, especially polycaprolactone (PCL) and their application in prosthodontic practice.

Setting and Design

A questionnaire based survey was carried out to assess the knowledge and awareness of PCL and its applications as provisional material in prosthodontic practice.

Materials and Method

A questionnaire-based descriptive study consisting of 10 questions related to different provisional materials and their applications in prosthodontic practice was formulated on Google Forms. The link was created and circulated among the prosthodontist faculty members of various dental institutes and private practitioners of India with the use of digital platforms such as E-mail and social media. The data were collected and examined using Microsoft Excel software for statistical evaluation.

Statistical Analysis Used

For this descriptive type of study, knowledge and awareness among prosthodontists across India was evaluated using Microsoft Excel software.

Results

The use of PCL was known only to 20.75% of prosthodontists. Moreover, its application and indications are known to only <1% of the study participants. Autopolymerizing resin was most commonly used for the custom tray and temporary base fabrication as well as temporization in crown and bridge prosthesis, while muscle deprogrammer and surgical template were commonly fabricated in heat-cure and clear acrylic resin, respectively. Pattern resin was found to be commonly used in splinting implant impression copings.

Conclusion

The use of PCL as a temporary denture base, custom tray, muscle deprogrammer, implant impression splinting, and provisional for crown and bridge and templates should be encouraged and incorporated to get benefits of its characteristic properties. Considering the overall performance of PCL, its use should be incorporated into prosthodontic research and practice.

Pulsed electromagnetic field stimulation may improve fusion rates in cervical arthrodesis in high-risk populations

OBJECTIVES

Pulsed electromagnetic field (PEMF) stimulation was evaluated after anterior cervical discectomy and fusion (ACDF) procedures in a randomized, controlled clinical study performed for United States Food and Drug Administration (FDA) approval. PEMF significantly increased fusion rates at six months, but 12-month fusion outcomes for subjects at elevated risk for pseudoarthrosis were not thoroughly reported. The objective of the current study was to evaluate the effect of PEMF treatment on subjects at increased risk for pseudoarthrosis after ACDF procedures.

METHODS

Two evaluations were performed that compared fusion rates between PEMF stimulation and a historical control (160 subjects) from the FDA investigational device exemption (IDE) study: a post hoc (PH) analysis of high-risk subjects from the FDA study (PH PEMF); and a multicentre, open-label (OL) study consisting of 274 subjects treated with PEMF (OL PEMF). Fisher's exact test and multivariate logistic regression was used to compare fusion rates between PEMF-treated subjects and historical controls.

RESULTS

In separate comparisons of PH PEMF and OL PEMF groups to the historical control group, PEMF treatment significantly (p < 0.05, Fisher's exact test) increased the fusion rate at six and 12 months for certain high-risk subjects who had at least one clinical risk factor of being elderly, a nicotine user, osteoporotic, or diabetic; and for those with at least one clinical risk factor and who received at least a two- or three-level arthrodesis.

CONCLUSION

Adjunctive PEMF treatment can be recommended for patients who are at high risk for pseudoarthrosis.Cite this article: D. Coric, D. E. Bullard, V. V. Patel, J. T. Ryaby, B. L. Atkinson, D. He, R. D. Guyer. Pulsed electromagnetic field stimulation may improve fusion rates in cervical arthrodesis in high-risk populations. Bone Joint Res 2018;7:124-130. DOI: 10.1302/2046-3758.72.BJR-2017-0221.R1.

Right ventricular dysplasia in an asymptomatic young man: an uncommon case with biventricular involvement and no known family history

A 33-year-old man had cardiomegaly on a routine x-ray examination. He was asymptomatic with no history of infarction, syncope, or palpitations. There was no family history of congenital heart disease or sudden death. Two-dimensional transthoracic echocardiography demonstrated marked enlargement of the right atrium and ventricle with severely depressed right and left ventricular function that was consistent with right ventricular dysplasia. The patient was treated with an angiotensin-converting enzyme inhibitor and did well for 6 months, but then developed symptomatic left-sided congestive heart failure. Short-term improvement was obtained with intravenous inotropic therapy, but he continued to have progressive symptoms of heart failure. Approximately 7 months after his initial presentation, the patient underwent orthotopic heart transplantation for intractable congestive heart failure. Pathologic examination of the explanted heart established the diagnosis of right ventricular dysplasia with left ventricular involvement. This is an uncommon presentation of right ventricular dysplasia with biventricular involvement and no known family history.

Hybrid therapy for ventricular arrhythmia management

Optimum arrhythmia management has evolved to couple ICD therapy with catheter ablative and drug therapy to attempt to eliminate or reduce arrhythmia risk. No longer should the clinician approach such therapy as a choice among single alternative strategies only. Optimum patient management includes not only recognition of the indications and benefits of such hybrid therapy but also a complete understanding of potential pitfalls of such therapy.

Calcium sulfate- and calcium phosphate-based bone substitutes. Mimicry of the mineral phase of bone

Calcium sulfate and calcium phosphate have provided the orthopedic surgeon a viable alternative to autogenous bone grafting as either an osteoconductive bone void filler or a bone graft extender. These materials mimic the mineral phase of bone and are resorbed at a rate similar to the rate of bone formation. Thus, they are able to provide some structural support and prevent ingrowth of fibrous tissue while facilitating creeping substitution by the host bone.

Morphologic changes in the ulnar nerve at the elbow with flexion and extension: a magnetic resonance imaging study with 3-dimensional reconstruction

We evaluated the morphology of the ulnar nerve and cubital tunnel with noninvasive magnetic resonance imaging (MRI). We used fresh human cadavers with the elbow in full extension, 90 degrees of flexion, and full flexion. For each elbow, 1-mm slices were imaged interpolated, and reconstructed into 3-dimensional data volumes, and then manually segmented before they were examined with sequential transverse sections, curved sections, and 3-dimensional images. The ulnar nerve follows a tortuous course in full extension, becomes progressively linear with incremental elbow flexion, shifts anteriorly in the cubital tunnel, and flattens against the medial epicondyle. The proximal and midportions of the cubital tunnel also change with flexion from round to elliptical. In addition, successive increases occur in the cross-sectional diameter of the mediolateral plane. The nerve is surrounded by fat throughout the cubital tunnel except adjacent to the medial epicondyle. These observations suggest that the ulnar nerve progressively stretch over the medial epicondyle occurs when the normal elbow is flexed. Direct compression areas of the ulnar nerve were not seen in our study of normal human elbows.

Craniofacial computer-assisted surgical planning and simulation

Computer-assisted planning and simulation of craniofacial surgery has progressed from development, through validation, and into clinical use. CT scans are transferred from the radiology department to a graphics workstation in the surgeon's office or laboratory, where data postprocessing and visualization for anatomic evaluation and surgical simulation are performed. Quantitative and qualitative comparative analyses between the plan/simulation and the actual postoperative result provide the feedback that validates or refutes the preoperative assessment and simulated intervention. The optimum surgical solution can be chosen from many possibilities. Interactive computer-assisted surgical simulation is also useful for morbidity-free training of inexperienced surgeons.

Formulation and evaluation of nifedipine injection

An attempt has been made to formulate a stable, aqueous injection of nifedipine (1) using the technique of hydrotropic solubilization. Sodium benzoate (2; 30% w/v) and sodium salicylate (3; 30% w/v) have been employed as the vehicle to prepare the injection of 1 in 1 mg/5 ml and 1 mg/2 ml concentration in either case. An accelerated stability study for 4 weeks at 8 degrees C, room temperature, 40 and 50 degrees C indicates maximum stability at 8 degrees C, suggesting the need of storage with refrigeration. Light stability study in the specially designed chamber indicates that covering the ampoules with black chart paper affords adequate stability to the 1 injection. The injections are also stable to autoclaving. Preliminary in vivo study in rats shows that the injection is effective.

Hydrotropic solubilization of nifedipine

Nifedipine (1), a drug practically insoluble in water, has been solubilized employing sodium benzoate (2) and sodium salicylate (3) as hydrotropes. In 30% w/v 2 solution the solubility of 1 increased 85 and 76 fold at 25 +/- 1 degree C and at 37 +/- 1 degree C respectively. The corresponding increase in solubility of 1 in 30% w/v 3 solution was 135 and 107 fold respectively. To study the mechanism of hydrotropic solubilization of 1, the solution properties of 2 and 3 over a concentration range of 1 to 30% w/v were undertaken. The probable mechanism involves a complexation type of interaction at a low concentration of hydrotrope, aggregation of the hydrotropic molecules and inclusion of 1 in these aggregates at high concentration; and structural changes in water caused by hydrotropes.