Impact of Sn/F Pre-Treatments on the Durability of Protective Coatings against Dentine Erosion/Abrasion

Effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials: An in vitro investigation

The aim of the study was to evaluate the effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials [CERASMART (GC); VITA ENAMIC (VITA Zahnfabrik); Lava Ultimate (3 M)] in comparison to feldspar ceramic (VITABLOCS Mark II, VITA Zahnfabrik) and resin composite materials (ceram.x universal, Dentsply Sirona). Daily brushing and acid exposure were simulated using a brushing apparatus and a solution of 0.5 vol% citric acid. Microhardness, surface roughness, and substance loss were measured at baseline and after simulation of 1 and 3 years of function. All materials showed a decrease in microhardness after 3 years and an increase in surface roughness (Ra) after 1 and 3 years. The Ra increase was statistically significantly lower for the resin-matrix ceramics than for feldspar ceramic and similar to composite material. After 3 years, only feldspar ceramic showed no significant substance loss. In conclusion, resin-matrix ceramics demonstrate reduced roughening compared to feldspar ceramics, potentially improving restoration longevity by preventing plaque buildup, but differences in abrasion resistance suggest the need for further material-specific research. Future research should aim to replicate clinical conditions closely and to transition to in vivo trials.

Omnidirectional Malleable Ring Retractor: New Approach to Retraction During Carotid Endarterectomy

OBJECTIVE

To resolve problems with retraction instruments in order to obtain shallow and flat operative field in procedures such as carotid endarterectomy, we developed a new malleable tin alloy omnidirectional retraction supporting (ORS) ring.

METHODS

The new ORS ring has an ellipse-shaped (major axis: 275 mm; minor axis: 192 mm) bar frame (4 mm × 6 mm). The bar has 22 equidistant outward protrusions (length, 12 mm; diameter, 2.5 mm). The frame is made of tin alloy with approximately 1% silver, which provides sufficient malleability to fit different cervical surgical approaches. Rubber bands ending with hooks are attached around the protrusions. The new ORS ring can be placed closer to the skin surface, and skin incision edges are horizontally retracted by the hooks attached in the desired direction. The hooks are repositioned in a stepwise fashion at deeper layers of the surgical wound following dissection for carotid artery exposure.

RESULTS

The tin alloy ORS ring was used in 30 carotid endarterectomies. As this ring could be closely positioned in all cases, the real depth of the operative fields (with all instruments in place) was reduced by the omnidirectional horizontal retraction without interference with surgical manipulations. Working on the distal internal carotid artery, such as putting a tacking suture in place and arteriotomy closure, could be easily performed.

CONCLUSIONS

The newly developed malleable tin alloy ORS ring can be a valuable instrument for the easy performance of surgery for cervical carotid lesions. Considering its advantages, it is better than conventional retractors and existing stainless steel ORS rings.

The Effect of SnCl2/AmF Pretreatment on Short- and Long-Term Bond Strength to Eroded Dentin

This study investigated the effect of SnCl₂/AmF pretreatment on short- and long-term bond strength of resin composite to eroded dentin mediated by two self-etch, MDP-containing adhesive systems. 184 dentin specimens were produced from extracted human molars. Half the specimens (n = 92) were artificially eroded, and half were left untreated. For both substrates, half the specimens were pretreated with SnCl₂/AmF, and half were left untreated. The specimens were treated with Clearfil SE Bond or Scotchbond Universal prior to application of resin composite. Microtensile bond strength (μTBS) was measured after 24 h or 1 year. Failure mode was detected and EDX was performed. μTBS results were statistically analyzed (α = 0.05). μTBS was significantly influenced by the dentin substrate (eroded < noneroded dentin) and storage time (24 h > 1 year; p < 0.0001) but not by pretreatment with SnCl₂/AmF or adhesive system. The predominant failure mode was adhesive failure at the dentin-adhesive interface. The content of Sn was generally below detection limit. Pretreatment with SnCl₂/AmF did not influence short- and long-term bond strength to eroded dentin. Bond strength was reduced after storage for one year, was lower to eroded dentin than to noneroded dentin, and was similar for the two adhesive systems.

The Availability of a Tin-Alloyed Omnidirectional Retractor-Supporting Ring for Ventriculoperitoneal Shunt Laparotomy

OBJECTIVE

We report the availability of a newly developed, malleable, tin-alloyed omnidirectional retractor-supporting (OD) ring for steady and safe ventriculoperitoneal (VP) shunt laparotomy.

METHODS

The OD ring is principally circular in shape, 15 cm in diameter, and is sufficiently malleable to be fitted to the abdominal wall. There are 22 outward protrusions 12 mm in length that are welded to the outside of the ring at regular intervals. The OD ring with twisted rubber bands attached around the protrusions is placed on the abdominal wall surrounding the skin incision. Then the edge is omnidirectionally retracted with blunt minihooks attached to the rubber bands. In our hospital from January 2016 to February 2017, 15 consecutive patients underwent a VP shunt procedure using the OD ring.

RESULTS

In a VP shunt procedure, our malleable, tin-alloyed OD ring could be smoothly placed on various types of abdominal walls. Moreover, our OD ring system provided a wider and shallower operative field allowing omnidirectional retraction during small laparotomy. Additionally, the OD ring system did not interfere with our surgical manipulations.

CONCLUSIONS

Our newly developed retraction system with a malleable, tin-alloyed OD ring and minihooks may allow safe and steady small laparotomy for VP shunt.

Energetics of Sn2+ isomorphic substitution into hydroxylapatite: first-principles predictions

The energetics of Sn²⁺ substitution into the Ca²⁺ sublattice of hydroxylapatite, Ca₁₀(PO₄)₆(OH)₂, has been investigated within the framework of DFT.