Thermal changes during implant site preparation with a digital surgical guide and slot design drill: an ex vivo study using a bovine rib model.

PURPOSE: In this study, we aimed to evaluate the degree of heat generation when a novel drill design with an irrigation slot was used with metal sleeve-free (MF) and metal sleeve-incorporated (MI) surgical guides in an environment similar to that of the actual oral cavity. METHODS: A typodont with a missing mandibular right first molar and 21 bovine rib blocks were used. Three-dimensional-printed MF and MI surgical guides, designed for the placement of internal tapered implant fixtures, were used with slot and non-slot drills. The following groups were compared: group 1, MI surgical guide with slot drill; group 2, MI surgical guide with a non-slot drill; and group 3, MF surgical guide with a slot drill. A constant-temperature water bath at 36°C was used. The drilling was performed in 6 stages, and the initial, highest, and lowest temperatures of the cortical bone were measured at each stage using a non-contact infrared thermometer. RESULTS: There were no temperature increases above the initial temperature in any drilling procedure. The only significant difference between the non-slot and slot groups was observed with the use of the first drill in the MI group, with a higher temperature in the non-slot group (P=0.012). When the heat generation during the first and the second drilling was compared in the non-slot group, the heat generation during the first drilling was significantly higher (P<0.001), and there was no significant difference in heat generation between the drills in the slot group. CONCLUSIONS: Within the limitations of this study, implant-site preparation with the surgical guide showed no critical increase in the temperature of the cortical bone, regardless of whether there was a slot in the drill. In particular, the slotted drill had a cooling effect during the initial drilling.

3D printed photoreactor with immobilized graphitic carbon nitride: A sustainable platform for solar water purification.

Solar-energy-enabled photocatalysis is promising for sustainable water purification. However, photoreactor design, especially immobilizing nano-sized photocatalysts, remains a major barrier preventing industrial-scale application of photocatalysis. In this study, we immobilized photocatalytic graphitic carbon nitride on chitosan to produce g-C3N4/chitosan hydrogel beads (GCHBs), and evaluated GCHB photoreactivity for degrading phenol and emerging persistent micropollutants in a 3D printed compound parabolic collector (CPC) reactor. The CPC photocatalytic system showed comparable performance with slurry reactors for sulfamethoxazole and carbamazepine degradation under simulated sunlight, and it maintained the performance for contaminant removal in real water samples collected from water/wastewater treatment plants or under outdoor sunlight irradiation. Global drinking water production was estimated for the CPC system, and it holds promise for small-scale sustainable water treatment, including, but not limited to, the production of high-quality potable water for single houses, small communities, rural areas, and areas impacted by natural disasters in both developed and developing countries.

Clinical Situations Associated with Inappropriately Large Regurgitant Volumes in the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method in Patients with Chordae Rupture.

BACKGROUND: Regurgitant volume (RVol) calculated using the proximal flow convergence method (proximal isovelocity surface area [PISA]) has been accepted as a key quantitative parameter for the diagnosis of and clinical decision-making with regard to severe mitral regurgitation (MR). However, a recent prospective study showed a significant overestimation of RVol by the echocardiographic PISA method compared with the MR volume measured using magnetic resonance imaging. We aimed to evaluate the frequency of overestimation of RVol by the PISA method and the clinical conditions that require a different quantitative method to correct the overestimation. METHODS: We retrospectively enrolled 166 consecutive patients with degenerative MR and chordae rupture, in whom RVol was measured using both the PISA and two-dimensional Doppler volumetric methods. The volumetric method was used to measure total stroke volume using the two-dimensional Simpson biplane method, and forward stroke volume was measured using pulsed Doppler tracing at the left ventricular (LV) outflow tract. RVol by the volumetric method was calculated using total stroke volume - forward stroke volume. Severe MR was defined as an RVol >60 mL. RESULTS: All patients had severe MR based on RVol by the PISA method, but 68 (41.1%) showed RVol by the volumetric method values of <60 mL, resulting in discordant results. The patients with discordant results were characterized by a higher prevalence of female sex, lower body surface area, smaller LV diastolic and systolic dimensions and volumes, smaller left atrial volume, smaller PISA angle, and lower frequency of flail leaflets (39.7% vs 62.2%, P = .004). Multivariate analysis revealed that LV end-diastolic volume (LVEDV) and PISA angle were independent factors, with the best cutoff LVEDV and PISA angle being 173 mL and 103°, respectively. During follow-up (median, 3.4 years; interquartile range, 2.0-4.8 years), mitral valve repair and replacement were performed in 103 and six patients, respectively. The 2-year mitral valve surgery-free survival rate was higher in the discordant group (51.8% ± 0.06% vs 31.2% ± 0.05%, P < .001). CONCLUSIONS: Even in the patients with documented chordae rupture, the PISA method alone resulted in inappropriate overestimation of MR severity in a significant proportion of patients. Thus, an additive quantitative method is absolutely necessary in patients with a small LVEDV or narrow PISA angle.

The vena contracta in functional tricuspid regurgitation: a real-time three-dimensional color Doppler echocardiography study.

BACKGROUND: The aims of this study were to evaluate the three-dimensional features and geometric determinants of the vena contracta (VC) in functional tricuspid regurgitation (TR) and to identify optimal width cutoff values for assessing functional TR severity. METHODS: Real-time three-dimensional full-volume and color Doppler and two-dimensional Doppler echocardiographic images were obtained in 52 patients with various degrees of functional TR and in sinus rhythm. The tricuspid valve and right ventricle were geometrically analyzed. VC widths parallel to the septal-lateral and anteroposterior directions, VC area, and effective regurgitant orifice area (EROA) using proximal isovelocity surface area methods on real-time three dimensional color Doppler images were measured. RESULTS: The septal-lateral VC width was 0.39 ± 0.37 cm smaller than the anteroposterior VC width (P < .001). VC widths and area were strongly correlated with EROA. The optimal cutoff values for the septal-lateral VC width, anteroposterior VC width, and VC area were 0.63 cm, 0.76 cm, and 0.37 cm(2), respectively, for moderate functional TR (EROA ≥0.2 cm(2)) and were 0.84 cm, 1.26 cm, and 0.57 cm(2), respectively, for severe functional TR (EROA ≥0.4 cm(2)). Multiple linear regression analyses showed that the septal leaflet tenting angle and septal-lateral annular diameter independently determined septal-lateral VC width, while the anterior leaflet tenting angle and anteroposterior annular diameter independently determined the anteroposterior VC width. CONCLUSIONS: Different VC width cutoff values should be applied according to the plane of view in functional TR, because the VC cross-sectional shape is ellipsoidal with a long anteroposterior direction. VC widths are determined by annular dilation and leaflet tenting in the corresponding directions.