A comparison study: The use of digital and conventional impression techniques in dental hygiene education.

PURPOSE/OBJECTIVES: The study aimed to assess the applicability of digital intraoral scanning in dental hygiene education and compare the quality, efficiency, and ease of use to conventional impression techniques. METHODS: Twenty-eight first-year dental hygiene students (DH1) at UTHealth Houston School of Dentistry (UTSD) participated in this 2022 study. Each student participated in two 4-h lab sessions. Students took traditional alginate impressions and digital intraoral scans using Planmeca Romexis on standardized teeth during the first and second sessions. Both techniques were assessed by faculty for quality and efficiency using a standardized rubric. Participants completed a post-survey providing insight into their perceptions of both techniques and ease of use. RESULTS: The study had 100% participation in the lab sessions and survey responses (N = 28). The results showed digital scanning produced a statistically higher quality product than conventional alginate impressions (p = 0.023). The study found no statistical difference in the efficiency between the two methods. The majority of students (82%) agreed that digital intraoral scanning was easy to use (p = 0.001), and 89% agreed they would use digital intraoral scanning in clinical courses to help with patient care (p = 0.03). CONCLUSION: In this study, dental hygiene students with limited clinical experience learned new technology and used it to produce quality impressions compared to the conventional technique, indicating the value of introducing digital dentistry early in dental hygiene education.

The usefulness of prostate specific antigen density as a screening method for prostatic carcinoma.

Prostate specific antigen (PSA) has been used extensively for monitoring the progression of prostatic cancer since its discovery in 1979. Unfortunately the measurement of PSA in serum is not sufficiently specific for early detection of prostatic carcinoma (CaP) as it is secreted by normal as well as hyperplastic or cancerous prostatic tissue. As serum PSA is the reflection of the number of prostatic epithelial cells, a small cancerous prostate gland having increased number of cells per unit volume leaks more PSA in serum than a benign, large gland. Thus the concept of PSA density (PSAD) has been proposed (the quotient of serum PSA divided by the volume of prostate in cubic centimeter) as an indicator for prostatic malignancy. In the present study pre-operative PSAD values of 65 cases of prostatic diseases were calculated [54 cases of benign prostatic hyperplasia (BPH) and 11 cases of C3P]. Serum PSA was measured by enzyme linked immunosorbent assay (ELISA) method and the prostatic volume was measured by transrectal ultrasonography (TRUS). Although 8 cases of BPH (14.8%) had raised PSA level, abnormal PSAD (0.1 or above) was noted in only 3 cases. All cases having PSAD value above 0.2 had carcinoma. The PSAD value above 0.1 in cases of CaP was found to be significant (p<0.001). By using PSAD as screening test the sensitivity increased from 85.1% to 94.4% and positive predictive value increased from 55.5% to 75%, compared to the detection of carcinoma by measuring PSA alone. The present study concludes that PSAD is more useful for prediction of CaP and the need of prostatic biopsy for early detection.

Prediction of amino acid sequence from structure.

We have developed a method for the prediction of an amino acid sequence that is compatible with a three-dimensional backbone structure. Using only a backbone structure of a protein as input, the algorithm is capable of designing sequences that closely resemble natural members of the protein family to which the template structure belongs. In general, the predicted sequences are shown to have multiple sequence profile scores that are dramatically higher than those of random sequences, and sometimes better than some of the natural sequences that make up the superfamily. As anticipated, highly conserved but poorly predicted residues are often those that contribute to the functional rather than structural properties of the protein. Overall, our analysis suggests that statistical profile scores of designed sequences are a novel and valuable figure of merit for assessing and improving protein design algorithms.

Molecular dynamics simulation of interaction of histone-like protein of mycobacterium tuberculosis (Hlpmt) and histone of clostridium pasteurianum (DBHclopa) with 35 based paired GC rich U-bend DNA.

Three dimensional structure of the first ninety two residues of histone like protein from Mycobacterium tuberculosis (Hlpmt) and histone of Clostridium pasteurianum (DBHclopa) are obtained here, on the basis of amino acid sequences of the two proteins, making use of secondary structure prediction programs, sequence search and HOMOLOGY based modeling tools available on Internet. The proteins were docked to a 35 base paired GC rich U bend DNA (U35DNA). Structures of proteins Hlpmt and DBHclopa; U35DNA; and complexes: Hlpmt-U35DNA and DBHclopa-U35DNA were optimized by molecular mechanics (MM) and simulated for 260 pico seconds (ps) in vacuum by molecular dynamics (MD) technique using AMBER 4.0 package with Cornell et al force field. The proteins, when simulated alone, showed compaction. DBHclopa showed larger compaction compared with Hlpmt. U35DNA when simulated alone straightened out and assumed a B-form. In the complexes, Hlpmt showed same order of compaction as in absence of DNA, while DBHclopa showed reduced compaction. In the presence of Hlpmt two ends of helicoidal axis of U35DNA came closer, but slightly out of plane, indicative of its role in overwinding and packaging double stranded DNA. DBHclopa did not give rise to DNA overwinding. The results show architectural role of Hlpmt and DBHclopa in DNA packaging and its sequence dependence.

Molecular dynamics simulation of conformational flexibility of alamethicin fragments in aqueous and membranous environment.

We present here results on molecular dynamics (MD) simulation on two fragments of channel forming antibiotic peptide Alamethicin, containing isoamino butyric acid (Aib). Simulations are carried out in aqueous and membranous environment in a bilayer of 39 molecules of Dimyristoyl phosphatidyl choline (DMPC). The peptides Boc-Pro-Aib-Ala-Aib-OBzl (Alam 1) and Boc-Leu-Aib-Pro-OBzl (Alam 2) were simulated from their crystallographic coordinates. The bilayers were built from two different conformations (A and B) of DMPC reported in crystal data. The P-N dipoles were arranged hexagonally with surface area per lipid molecule 66.5 A degrees 2 and P-P separation across the bilayer 34 A degrees. They were hydrated by 28.6 and 25.5 water molecules per DMPC molecule. Simulations are done using AMBER 4.0 package in constant number volume temperature (NVT) condition for 100 pico seconds (ps) in aqueous environment and 250 ps of equilibrated bilayer. Geometric parameters of lipids as: bilayer thickness, order parameter of the chains, transfraction of chain torsional angles were monitored. We also monitored geometric parameters of the peptides as backbone torsional angles, distances amongst C alpha atoms, angles between C alpha atoms, movement of center of gravity (CG) along and perpendicular to bilayer normal. We find that membrane bilayer is slightly disturbed due to the presence of peptides. In case of alam 2 in water angles phi 1 and phi 3 showed larger variation in water compared to same in the bilayer. The peptide conformation is more stable in DMPC bilayer. However the peptides showed movement along and perpendicular to bilayer normal. This we believe is due to hydrophobic nature of these peptides.

Hepatic histology in chronic liver disease in hepatitis B surface antigen positive cases.

The spectrum of histological changes in needle biopsies of the liver tissue was analysed in 43 patients with chronic liver disease who were positive for hepatitis B surface antigen (HBsAg) in their sera. Majority of the patients were around 40 years and there was a male predominance. According to histopathological pattern, there were 18 (41.8%) cases of chronic active hepatitis, 16 (37.2%) cases of inactive cirrhosis, 3 (6.9%) cases of chronic persistent hepatitis and 2 (4.7%) cases of chronic lobular hepatitis and hepatoma each. Two (4.7%) cases could not be exactly categorised into any particular histological entity. The inflammation, hepatic cell necrosis and fibrosis were more marked in cases of chronic active hepatitis without past history of jaundice. Micronodular cirrhosis was the most common histological pattern in the study. Shikata orcein stain for detection of HBsAg in the hepatocytes was positive in 8 (18.6%) cases only.

Collision tumor of gastrointestinal tract.

A rare combination of multiple adenomatous polyps of the colon and carcinoid tumor of the ileum in a 54-year-old man is reported.