Intrusion in implant-tooth-supported fixed prosthesis: an in vitro photoelastic stress analysis

BACKGROUND AND OBJECTIVE: Intrusion of natural teeth is a very common and interesting problem associated with implant-assisted fixed partial prostheses. Various theories have been put forth to explain this phenomenon, most of which revolve around the philosophy of exertion of excessive forces onto the natural tooth in a combination fixed partial denture. This photoelastic study examines the current theories revolving around intrusion and evaluates whether natural tooth intrusion is a definite possibility in an implant-tooth-connected fixed partial prosthesis. MATERIALS AND METHODS: A two-dimensional photoelastic method was employed for testing and analysis. Two sets of photoelastic models were fabricated, one depicting a totally tooth-supported situation and the other an implant-tooth-supported situation. A rigid type and non-rigid type of connection were also incorporated into the fixed partial denture used in the both the situations in the study. Loads were applied on the anterior and posterior abutments and the pontic regions in both sets of models and the fringe patterns were photographically recorded for analysis. RESULTS AND CONCLUSION: The forces were proportionately consistent with the increase in applied loads in both the situations. The use of a non-rigid connection did not show any major significance but in fact may be erroneous. The forces were considerably higher in the implant-tooth-connected situation. The results indicated that the differences in the forces exerted were not light and continuous and may not cause tooth intrusion. Natural tooth intrusion may be caused by reasons other than excessive forces and needs further investigation.     

Benign broncho-esophageal fistula in adult- Two case reports

Broncho-esophageal fistula (BEF) in adult is commonly due to malignancy. Benign BEF is rare. The common causes are mediastinal inflamation, due to tuberculosis, histoplasmosis, etc. This, can present with chronic cough, asthma or pulmonary sepsis. The symptoms are not as pronounced as in tracheo-esophageal fistula. Barium swallow helps to confirm the diagnosis. Esophagoscopy and bronchoscopy are routine to exclude any associated pathologies and also to evaluate the distal esophagus for any obstruction. Excision of the tract with closure of both ends and soft tissue interposition is curative. In both the cases there was no evidence of mediastinal inflamation like periesophageal adhesions or fibrosis or lymphadenopathy. Both the patients were treated surgically with good results.     

Response to pulmonary vasodilators in infants with congenital diaphragmatic hernia

Background

Congenital diaphragmatic hernia (CDH) is associated with lung hypoplasia, cardiac dysfunction and pulmonary hypertension. Inhaled nitric oxide (iNO) and milrinone are commonly used pulmonary vasodilators in CDH. We studied the hemodynamic effects of iNO and milrinone in infants with CDH.

Methods

A retrospective chart review was performed of all CDH infants admitted to two regional perinatal centers and infants classified into three groups: No-iNO group; iNO-responders and iNO-nonresponders. Oxygenation and hemodynamic effects of iNO and milrinone were assessed by blood gases and echocardiography.

Results

Fifty-four percent (39/72) of infants with CDH received iNO and 31% of these infants (12/39) had complete oxygenation response to iNO. Oxygenation response to iNO was not associated with a decrease in right ventricular pressures (RVP) or ECMO use. Four infants (33%) in the iNO-responder group and eight infants (30%) in the iNO-nonresponder group received milrinone. Milrinone lowered RVP and improved ejection fraction (EF). Response to iNO was associated with improved oxygenation to milrinone and increased survival following ECMO (67 vs. 20% among nonresponders).

Conclusions

Response to inhaled nitric oxide in combination with milrinone may be associated with improved oxygenation and better survival after ECMO in infants with CDH.

     

Tear Fluid Protein Changes in Dry Eye Syndrome Associated with Rheumatoid Arthritis: A Proteomic Approach

Purpose

Sjögren syndrome (SS) secondary to rheumatoid arthritis (RA) affects lacrimal and salivary glands, and therefore dry eye syndrome (DES) is more prevalent in patients with RA. This study used a proteomic approach to identify potential biomarkers in tear of DES secondary to RA (DES-RA).

Colchicine attenuates compensation to negative but not to positive lenses in young chicks

Optic nerve-sectioned (ONS) chick eyes are capable of emmetropisation, but these eyes also exhibit increased hyperopia without any visual manipulations, which suggests altered eye growth regulation. These altered growth changes may be related to the loss of retinal ganglion cells that follows nerve lesioning. Colchicine, which also destroys retinal ganglion cells in chicks, was used to further examine the effects of retinal ganglion cell loss on emmetropisation. Growth responses of +10D and -10D lens-wearing colchicine-injected eyes were compared to those of +10D and -10D lens-wearing saline-injected eyes, respectively. Changes after removal of lenses were also analysed. Prior to lens-wear, colchicine-injected eyes exhibited longer optical axial lengths (OL; distance from cornea to retina; p=0.0185) but no differences in refractive error (RE; p=0.6588). Although myopic shifts were not significant for -10D lens-wearing colchicine-injected eyes (p=0.5913), but were for the saline-injected eyes (p=0.0034), these changes were not different (p=0.1646). However, -10D lens-induced OL changes in colchicine-injected eyes showed insignificant (p=0.2214) and reduced (p=0.0102) changes compared to those of saline-injected eyes. +10D lens-treated colchicine-injected eyes showed significant hyperopic shifts (p<0.0001) and significant reductions in OL (p<0.0001) that were similar to those of saline-injected eyes (p=0.7990 and p=0.1495, respectively). Growth responses in eyes recovering from -10D lenses were minimal, with REs unaffected (p=0.3325), but OL reductions affected (p=0.0199) by colchicine. Colchicine-injected eyes recovering from +10D lenses showed significant myopic shifts (p=0.0003) and OL elongations (p<0.0001) that were similar to those of saline-injected eyes (p=0.3999 and p=0.4731, respectively). The results showing that colchicine suppresses the ability to respond to negative lenses but leaves compensation to positive lenses relatively unchanged, are opposite to those of optic nerve sectioned eyes. We speculate that the differences are probably related to the way retinal cells are lost.     

Wavefront-guided versus wavefront-optimized laser in situ keratomileusis: contralateral comparative study

PURPOSE: To compare the outcomes of wavefront-guided and wavefront-optimized treatment in fellow eyes of patients having laser in situ keratomileusis (LASIK) for myopia. SETTING: Medical and Vision Research Foundation, Tamil Nadu, India. METHODS: This prospective comparative study comprised 27 patients who had wavefront-guided LASIK in 1 eye and wavefront-optimized LASIK in the fellow eye. The Hansatome (Bausch & Lomb) was used to create a superior-hinged flap and the Allegretto laser (WaveLight Laser Technologie AG), for photoablation. The Allegretto wave analyzer was used to measure ocular wavefront aberrations and the Functional Acuity Contrast Test chart, to measure contrast sensitivity before and 1 month after LASIK. The refractive and visual outcomes and the changes in aberrations and contrast sensitivity were compared between the 2 treatment modalities. RESULTS: One month postoperatively, 92% of eyes in the wavefront-guided group and 85% in the wavefront-optimized group had uncorrected visual acuity of 20/20 or better; 93% and 89%, respectively, had a postoperative spherical equivalent refraction of +/-0.50 diopter. The differences between groups were not statistically significant. Wavefront-guided LASIK induced less change in 18 of 22 higher-order Zernike terms than wavefront-optimized LASIK, with the change in positive spherical aberration the only statistically significant one (P= .01). Contrast sensitivity improved at the low and middle spatial frequencies (not statistically significant) and worsened significantly at high spatial frequencies after wavefront-guided LASIK; there was a statistically significant worsening at all spatial frequencies after wavefront-optimized LASIK. CONCLUSION: Although both wavefront-guided and wavefront-optimized LASIK gave excellent refractive correction results, the former induced less higher-order aberrations and was associated with better contrast sensitivity.     

Specific requirements for elements of the 5' and 3' terminal regions in flavivirus RNA synthesis and viral replication

We initially studied requirements for 5' and 3' terminal regions (TRs) in flavivirus negative strand synthesis in vitro. Purified West Nile (WNV) and dengue-2 (DV2) RNA polymerases were both active with all-WNV or all-DV2 subgenomic RNAs containing the 5'- and 3'TRs of the respective genomes. However, subgenomic RNAs in which the 5'-noncoding region (5'NCR) or the 5'ORF (nts 100-230) in the 5'TR were substituted by analogous sequences derived from the heterologous genome were modestly to severely defective as templates for either polymerase. We also evaluated the infectivity of substitution mutant WNV genome-length RNAs. All WNV RNAs containing the DV2 3'SL were unable to replicate. However, WNV RNAs containing substitutions of the 5'NCR, the capsid gene, and/or 3'NCR nt sequences upstream from the WNV 3'SL, by the analogous DV2 nt sequences, were infectious. Combined results suggested that replication was not dependent upon species homology between the 3'SL and NS5.