Influence of internal-gap width and cement type on the retentive force of zirconia copings in pullout testing

Objectives

The purpose of this study was to evaluate the influence of internal-gap width and cement type on the retentive force of zirconia copings.

Methods

A CAD/CAM system was used to mill 48 identical abutments on extracted human molars and fabricate 48 zirconia copings. The internal-gap width for cement was set to 40 μm or 160 μm (n = 24 each). Three cement types (Panavia F, RelyX Unicem, and RelyX Luting) were used with each internal-gap width (n = 8/cement type). The intaglio surfaces of the copings were airborne-particle abraded, and each coping was cemented onto the corresponding abutment using the indicated luting agent. After 10,000 cycles of thermocycling, the retentive force was evaluated by pullout tests. Kruskal–Wallis and Wilcoxon Rank Sum tests were used for data analysis (α = 0.05).

Results

In the 40-μm gap groups, Panavia F had the highest mean retentive force compared to RelyX Unicem and RelyX Luting (P < 0.000). In 160-μm gap groups, RelyX Unicem had the highest mean retentive force compared to Panavia F and RelyX Luting (P < 0.000).

Conclusions

With the increase in internal gap width, a resin cement with self-etching agents as a co-initiator for autopolymerization resulted in significantly decreased retentive force, whereas a resin-modified glass ionomer cement or a self-adhesive resin cement did not. Use of resin cements rather than resin-modified glass ionomer cements improved the retentive force of zirconia copings regardless of the amount of internal gap width.     

Clearance rates of residual stone fragments and dusts after endoscopic lithotripsy procedures using a holmium laser: 2-year follow-up results

Purpose

To investigate the spontaneous clearance rates of remnant particles following miniaturized percutaneous nephrolithotomy (mini-PCNL) and retrograde intrarenal surgery (RIRS).

Methods

Among 624 patients who underwent mini-PCNL or RIRS at our institution from 2011 to 2015, we collected data of 247 patients with 2 years of follow-up. Of these, we included 148 patients with unilateral renal stones between 10 and 30 mm, as well as remnant particles after surgery. The size criteria of dusts and residual fragments (RFs) were, respectively, <1 and <3 mm.

Results

After excluding 22 patients, 126 patients (RFs = 21, dusts = 98, and both RFs and dusts = 7) were analyzed. Mean age was 56.5 (±14.4) years, and mean stone size was 19.5 (±12.5) mm. The mean follow-up period was 18.5 (± 12.9) months. In patients whose remnant particles were naturally eliminated following lithotripsy, the mean stone passage time was 9.0 (±9.3) months in the dusts and 13.9 (±11.1) months in the RFs groups (P = 0.135). Remnant particles disappeared in 42 out of 105 patients (40.0 %) in dusts and 7 out of 28 patients (25.0 %) in RFs groups (P = 0.187). The size of dusts and RFs increased, respectively, in 18.1 % (19/105) and 28.6 % (8/28) of patients with remnant particles during the follow-up period.

Conclusions

The presence of dusts and RFs was poor prognostic factors in patients underwent renal stone surgery using a holmium laser. Complete residual stone removal by using a basket or dusts eradication by irrigation for an adequate time during surgery can be a good surgical strategy.

     

Clinically distinguishing between appendicitis and right-sided colonic diverticulitis at initial presentation

PURPOSE: Most patients diagnosed with right-sided colonic diverticulitis complain of right lower quadrant pain, which is frequently confused for appendicitis and therefore may result in unnecessary emergency surgery. In this paper we intend to differentiate between right-sided colonic diverticulitis and appendicitis by initial presentation in the emergency department. MATERIALS AND METHODS: We retrospectively reviewed the medical records of 450 patients between January 1997 and July 2003. Among these patients, 92 with right-sided colonic diverticulitis were classified as group I; 268 patients with simple appendicitis were classified as group II; and 90 patients with perforated appendicitis were classified as group III. RESULTS: Prodromal symptoms were less common in group I (p < 0.05) than in the other groups. In comparing the location of maximal tenderness among groups, 19.6% of group I patients complained of maximal tenderness at a point lateral to McBurney's point, a greater percentage than those in groups II and III (p=0.002). Group I experienced less leukocytosis (10,913.8/mm(3)) than did groups II (13,238.3/mm(3)) and III (15,589.3/mm(3)). The percentage of segmented forms in the differential counts was also smaller in group I (73.6%) than in groups II (79.1%) and III (81.8%). In addition, the proportion of lymphocytes was larger in group I (17.7%) than in groups II (13.9%) and III (9.3%). CONCLUSION: Among patients complaining of right lower quadrant pain in an emergency setting, right-sided colonic diverticulitis must be considered in the following conditions to avoid unnecessary emergency operations: lack of prodromal symptoms, tenderness at a point lateral to McBurney's point, and absent or mild leukocytosis with a low fraction of segmented forms and a high fraction of lymphocytes in the CBC.     

Mechanistic Model for Blood Pressure and Heart Rate Changes Produced by Telmisartan in Human Beings

Telmisartan, an angiotensin receptor blocker (ARB), is indicated for the treatment of essential hypertension. This study aimed to develop a mechanistic model of telmisartan drug effect in human beings using non‐invasive markers. Data were acquired from a previous study where telmisartan 80 mg was given once daily for 6 days. Systolic (SBP) and diastolic blood pressure (DBP) and heart rate (HR) were measured before dosing for days 1–5 and serially after the last dose. Mean arterial pressure (MAP) and pulse pressure (PP) were calculated from SBP and DBP. Relationships between MAP, PP, HR and total peripheral resistance (TPR) were developed. Circadian variation was incorporated into PP and HR, and TPR was assumed to adjust itself in response to changes in PP and HR based on baroreflex mechanism. Drug effects were then described as lowering the set point of MAP through TPR with a physiological feedback effect stimulating HR and PP. Drug concentrations were described by a two‐compartment disposition model with first‐order absorption and lag time, and first‐order elimination. Circadian variation was described by cosine functions, having periods of 12 and 24 hr. A log‐linear model was used to describe drug effect, with estimated drug effect parameter of 0.051/hr. Estimated fractional turnover rate of PP, HR and TPR was 11.2 hr. The model successfully described the time courses of these cardiovascular variables. This work demonstrated the feasibility of using non‐invasive cardiovascular measurements to derive a mechanistic model for telmisartan in human beings. The model may be suitable for other ARBs.