New Ultrasonic Tip Decreases Uninstrumented Surface and Debris in Flattened Canals: A Micro–computed Tomographic Study

IntroductionThe preparation of flattened root canals using reciprocating or rotary nickel-titanium instruments associated with the Flatsonic ultrasonic tip (Helse Ultrasonic, Santa Rosa de Viterbo, SP, Brazil) was evaluated by micro–computed tomographic imaging.MethodsTwenty-four flattened distal canals of mandibular molars with a buccolingual diameter 4 or more times larger than the mesiodistal diameter were selected. The root canals were randomly divided into 2 experimental groups for preparation: a Reciproc Blue (RB; VDW GmbH, Munich, Germany) 40/.06 file in reciprocating motion or ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 40/.01 and 40/.05 files in rotary motion (n = 12). A complementary preparation was performed with the Flatsonic ultrasonic tip for both preparations. Micro–computed tomographic scanning at a resolution of 8.74 μm was performed before and after preparation with the nickel-titanium instruments and after the use of the Flatsonic tip. The percentages of increase in volume, debris, and uninstrumented surface were analyzed. The data obtained were submitted to the paired and unpaired t test, analysis of variance, and the Tukey test (α = 5%).ResultsThe percentage increase in volume, debris, and uninstrumented surface was similar between RB and PDL in the entire root canal (P > .05). The PDL promoted a lower percentage of debris in the cervical third and a lower percentage of increase in volume in the apical third in comparison with RB (P < .05). The Flatsonic decreased debris and uninstrumented surface after PDL preparation in all thirds (P < .05). After preparation with RB, the Flatsonic decreases the debris in the cervical third and the uninstrumented surface in the cervical and middle thirds (P < .05).ConclusionsThe preparation of flattened root canals using RB or PDL produced a high percentage of debris and uninstrumented surface. The Flatsonic ultrasonic tip significantly improved the cleaning of flattened root canals.     

Clinical improvement of gingival conditions following ultrasonic versus hand instrumentation of periodontal pockets

A study utilizing a split-mouth design in 18 subjects and with four operators was performed in order to compare the effect of hand and ultrasonic instrumentation of periodontal pockets. Contralateral pairs of teeth with pockets of comparable depth were treated by either hand or ultrasonic instruments. Instrumentation was repeated after 4 weeks. Pocket depth, bleeding on probing and gingival fluid measurements were used for evaluation. A gradual reduction of pocket depth and number of bleeding points took place throughout the 8-week experimental period. Clinically significant differences were not observed comparing the effect of hand instruments to ultrasonics for any of the operators. The amounts of gingival fluid were similar for both methods of instrumentation at the final examination. Thus, the present study failed to demonstrate any significant differences between the effect of ultrasonic root debridement and hand instrumentation in the treatment of 4--6 mm deep periodontal pockets.     

Ultrasonics Sonochemistry Assisted Preparation of Polysiloxane Main‐Chain Liquid‐Crystalline Elastomers

For the first time, an ultrasonics sonochemistry method is developed to promote the one‐pot hydrosilylation polyaddition polymerization and crosslinking reaction in the preparation of polysiloxane main‐chain liquid‐crystalline elastomers (MC‐LCEs). Due to the extraordinary effect of acoustic cavitation, the polyaddition polymerization and crosslinking reaction can be successfully carried out in an ordinary laboratory ultrasonic cleaner at room temperature, and generates the LCE matrix network in about 30 min. The prepared MC‐LCEs demonstrate good quality, good properties, and stimuli‐actuation performances. Compared to the traditional thermal processing methods for preparing polysiloxane MC‐LCEs, this method exhibits superior properties rapidly, with high convenience and efficiency, and can be a path for batch fabrication at low cost. The work also demonstrates that the ultrasonics sonochemistry method is effective in generating linear main‐chain liquid crystal polymers through hydrosilylation polyaddition and polysiloxane side‐chain LCE matrix through hydrosilylation crosslinking reaction, thus confirming the high availability of ultrasonics sonochemistry in the processes of hydrosilylation polymerization, crosslinking reactions, or synchronous polymerization and crosslinking reactions.     

Hot spots created at skin-air interfaces during ultrasound hyperthermia

It is well known that ultrasound beams will be completely reflected at a soft-tissue-gas interface. The reflected beam is contributing to the power absorption at the tissue interface and may cause a hot spot which could prevent therapeutic temperatures at the treatment volume. In this study the temperature elevation caused by a reflected ultrasound beam at the skin surface has been investigated in dogs' thighs in vivo. The magnitude of the hot spot was quantified and the effect of entrance angle was also investigated. In addition, the possibility of eliminating the hot spot by coupling the beam out of the tissue was studied. The results showed that the temperature elevation can be up to four times larger at the skin-air surface than in resting muscle under similar exposure. The geometry of the reflecting surface had a significant effect on the temperature distribution. When the sound was coupled out of the tissue the magnitude of the temperature elevation at the skin reduced to less than half (depending on the geometry) but was still larger than temperatures measured in muscle. These results suggest the need for computerized treatment planning for scanned focused ultrasound treatments.     

Influence of plaque calcium on neointimal hyperplasia following bare metal and drug-eluting stent implantation.

OBJECTIVES: To examine the influence of vessel wall calcium on neointimal hyperplasia (NIH) following bare metal stent (BMS) and drug-eluting stent (DES) implantation. BACKGROUND: While procedural complications with coronary stenting in calcified lesions are well reported, little is known about subsequent NIH on plaque calcium following either BMS or DES implantation. METHODS: In the Study to COmpare REstenosis Rate between QueST and QuaDDS-QP2 (SCORE) trial, 6 months follow-up volumetric intravascular ultrasound data were available for 41 lesions (BMS, 19; DES, 22). NIH thicknesses on superficial, deep, and noncalcified plaque were calculated at every 0.5 mm intervals over the stented segment. Calcified and less-calcified cross-sections were defined as those containing arcs of plaque calcium > or = 90 degrees and < 90 degrees , respectively. RESULTS: In BMS, mean NIH thickness on both superficial (0.24 +/- 0.23 mm) and deep calcium (0.25 +/- 0.21 mm) was significantly smaller than that of noncalcified plaque (0.31 +/- 0.22 mm) (P < 0.0005). NIH area was significantly smaller in calcified cross-sections compared to less-calcified cross-sections (2.1 +/- 1.2 mm2 vs. 3.1 +/- 1.9 mm2, P < 0.0001). While in contrast, in DES, mean NIH thickness was similar, irrespective of the presence or location of calcium (0.03 +/- 0.05 mm vs. 0.03 +/- 0.06 mm vs. 0.03 +/- 0.05 mm, superficial vs. deep vs. noncalcified plaque, P = NS). NIH area was also similar between calcified and less-calcified cross-sections (0.3 +/- 0.6 mm2 vs. 0.3 +/- 0.6 mm2, P = NS). CONCLUSIONS: These results suggest that while plaque calcium may influence NIH following BMS implantation, NIH suppression using DES does not appear to be affected by the presence or location of calcium.     

Clarithromycin as an Adjunct to One‐Stage Full‐Mouth Ultrasonic Periodontal Debridement in Generalized Aggressive Periodontitis: A Randomized Controlled Clinical Trial

Background: The aim of the present study is to evaluate the periodontal clinical and microbiologic responses and possible adverse effects of clarithromycin (CLM) combined with periodontal mechanical therapy in the treatment of patients with generalized aggressive periodontitis. Methods: Forty patients were selected and randomly assigned into one of two groups: 1) CLM (n = 20): one‐stage full‐mouth ultrasonic debridement (FMUD) associated with CLM (500 mg, every 12 hours for 3 days); and 2) placebo (n = 20): FMUD associated with placebo pills. Clinical and microbiologic parameters were evaluated at baseline and 3 and 6 months postoperatively. Results: Both treatments presented statistically significant clinical and microbiologic improvements. However, the CLM group presented lower means of probing depth for pockets ≥7 mm at 6 months (4.0 ± 1.7 mm) compared with the placebo group (4.7 ± 1.3 mm) (P = 0.04). In addition, the CLM group also presented greater reduction of Porphyromonas gingivalis (Pg) DNA counts at 6 months (P = 0.0001). Conclusion: Results from this study suggest both treatments are effective; however, adjunct use of CLM to FMUD leads to better reduction of deep pockets and Pg at 6 months compared with FMUD alone.     

Permanent Deformation and Stiffness Degradation of Open Hole Glass/PA6 UD Thermoplastic Composite in Tension and Compression

UD glass/PA6 coupons with an open hole are subjected to tensile and compressive loading. Three layups: [0/90]_5s, [+45/−45]_5s and [+45/0/−45/90]_3s with a shape based on ASTM D5766 were tested. Both monotonic loading as well as loading–unloading–reloading tests were executed. The strain field on the sample surface was measured with digital image correlation. This allowed identifying the distribution of the strain field during loading, permanent deformation and the evolution of the sample elastic modulus. This information is not frequently measured. Yet, it is vital for the development and validation of advanced failure models. The results indicate that the thermoplastic matrix allows large plastic deformation under tensile loading for the specimens with layup [+45/−45]_5s. In addition, the specimen elastic modulus reduces by about 70%. The other layups show minor permanent deformation, while the elastic modulus reduces by up to 15%. Furthermore, the quasi-isotropic laminate shows a significant post-failure load-bearing capacity under compression loading. The results are complemented with post-mortem damage and fracture observations using optical microscopy and ultrasound inspection.     

���ֲ�ͬ����Ԥ�����ܺ�Ը��ⲿ���̶ȵıȽ��о�

目的比较5种不同方法预备根管后对根尖1／3根管壁的清洁能力。方法将2007年12月至2008年3月在大连市口腔医院颌面外科门诊拔除的60颗离体牙随机分为6组,每组10颗。各组的牙齿先使用Protaper进行根管预备,然后使用不同的方法处理根管壁,分别为：A组H2O2和生理盐水（对照组）、B组EDTA凝胶和5．25％的NACLO,C组超声波荡洗根管、D组Nd：YAG激光、E组超声波（蒸馏水）＋EDTA、F组：超声波（5．25％NAcL0）＋EDTA。完成之后将样本纵向剖开,扫描电镜观察根管壁的界面,比较根尖1／3根管壁的清洁程度和牙本质小管的状态。结果对照组（A组）牙齿根尖部被玷污层全部覆盖,未见开放的牙本质小管;各实验组（B、C、D、E、F组）牙齿根尖部根管壁玷污层不同程度被去除。B、C、D、E、F组根尖1／3玷污层的评分与A组比较,差异有统计学意义（P〈0．05）;5个实验组间根尖1／3玷污层的评分比较,D组与E组差异无统计学意义（P〉0．05）,其余各组间差异均有统计学意义（P〈0．05）。结论5种不同的方法在一定程度上可去除根尖部的玷污层,以超声波（5．25％NACLO）＋EDTA处理根管壁的效果最佳。