Effect of lateral bone augmentation procedures in correcting peri-implant bone dehiscence and fenestration defects: A systematic review and network meta-analysis

Purpose

The aim of the present systematic review was to evaluate the effect of different lateral bone augmentation (LBA) procedures on the complete correction of a peri‐implant bone dehiscence (BD) or fenestration (BF) from implant placement to implant surgical uncovering.

Methods

Electronic (Medline, Scopus, and Cochrane databases) and hand literature searches were performed for studies including at least one treatment arm where any LBA had been applied to correct a BD/BF at implant placement (T0). Studies where BD/BF was left untreated were also retrieved as negative control. Data from 24 selected articles were used to perform a network meta‐analysis. Based on the proportion of nonresolved BD/BF at implant surgical uncovering (T1), a hierarchy of LBA procedures, and was determined. Spontaneous healing (i.e., exposed implant surface covered by a full‐thickness flap; SELF) was also included in the hierarchy. Resorbable membrane + bone graft (RM + BG) was used as reference group. An analysis on the effect of nonhuman (NHBS) vs human (HBS) derived bone substitutes was also performed. NHBS was used as the reference group.

Results

No statistically significant differences were found among treatments for the proportion of nonresolved BD/BF. SELF performed substantially worse compared to RM + BG (OR: 5.78 × 10, CI: 4.83 × 10 – 1.3 × 10⁸⁶). Treatment based on a combination of a graft material and membrane/periosteum appeared to perform slightly better than treatments using graft material or membrane alone. NHBS appeared to perform better than HBS.

SELF had the worst effect among all treatments for both BD/BF height reduction (BDH) and BD/BF width reduction (BDW). Nonresorbable membrane (NRM) and patient's own periosteum (PERI) + BG showed greater increases in buccal bone thickness than RM + BG.

Conclusion

Reconstructive treatment (including use of graft alone, membrane alone, or combinations of grafts and either membrane or patient's own periosteum) of a BD/BF at implant placement favorably and significantly impacts on the probability to obtain complete correction of the BD/BF at implant uncovering when compared to full‐thickness flap repositioning on the BD/BF. When using a bone substitute, a nonhuman derived one may be suggested.

Note: Self-biased voltage to suppress secondary electrons by a ZnO varistor in a compact pulsed neutron generator

A large amount of back streaming electrons will bring about a part of current drain on power supply, cause sparking or high-voltage breakdowns, and affect the neutron yield and waveform for a compact sealed-tube pulsed neutron generator. A novel idea which uses a ZnO varistor to provide a constant self-biased voltage to suppress the secondary electrons is introduced. The I-V curve for the ZnO varistor was measured in the experiment. The effects of suppressing the secondary electrons were investigated using a ZnO varistor, linear resistors, and an independent power supply, respectively. The results show that the secondary electrons are suppressed effectively by the compact ZnO varistor, while not increasing the size and the component of the device. It is a promising design for compact sealed-tube neutron generators.

Note: Triggering behavior of a vacuum arc plasma source

Axial symmetry of discharge is very important for application of vacuum arc plasma. It is discovered that the triggering method is a significant factor that would influence the symmetry of arc discharge at the final stable stage. Using high-speed multiframe photography, the transition processes from cathode-trigger discharge to cathode-anode discharge were observed. It is shown that the performances of the two triggering methods investigated are quite different. Arc discharge triggered by independent electric source can be stabilized at the center of anode grid, but it is difficult to achieve such good symmetry through resistance triggering. It is also found that the triggering process is highly correlated to the behavior of emitted electrons.

Operant performance following tail-pinch in the rat: effects of d-amphetamine

To extend the investigation of tail-pinch induced behavioral changes, rats performing on a differential reinforcement of low rates of 10 sec (DRL10), a fixed-interval of 60 sec (F160), and a fixed-ratio of 20 (FR20) schedules were exposed to a paper clip applied to the tail. While a 10 min tail-pinch conducted 1 hr before operant sessions significantly altered the DRL10 behavior, this stressor had little effect on either F160 or FR20 responding. Marked DRL10 behavior performance changes following tail-pinch included increases in the number of lever presses, decreases in the number of the reinforcers, and disruption in the frequency distribution of inter-response times (IRT). These DRL10 operant deficits were diminished when the subject received a tail-pinch pretreatment followed by d-amphetamine treatment (0.2 and 2.0 mg/kg). In combination with biochemical data from others, the present results suggest that catecholamine systems are involved in modulation of DRL10 behavior following tail-pinch.

Distinct accumbal subareas are involved in place conditioning of amphetamine and cocaine

In considering the heterogeneous function of the nucleus accumbens (NAC), the present work evaluated the conditioned place preference (CPP) after local infusion of d-amphetamine (AMP; 10, 15 microg/side) or cocaine (COC; 50, 100 microg/side) into two subareas of NAC, core and shell. A regular two-compartment CPP apparatus was used to test the place conditioning effects after 6 pairings of drug in one compartment and 6 pairings of vehicle in the other one. Significant CPP was observed with either AMP infused in the core area or COC infused into the shell area. Neither AMP in shell nor COC in core significantly produced CPP. These results indicate important differences between two neural substrates within NAC for the rewarding effects of AMP and COC on the CPP task.