Malleostapedotomy for otosclerosis,our experience of nitinol piston on twelve patients

ObjectiveMalleostapedotomy allows to completely by-pass the incus in otosclerosis surgery. Recently its use has been rivaled by hydroxyapatite cement for cases of mild and moderate necrosis of the incus. However, it remains gold standard for cases of extensive necrosis, incus dislocation, or epitympanic fixation. Modern heat-crimping pistons make surgery easier and safer. This study focuses on our experience with this technique.MethodsRetrospective analysis of patient’s files and pre- and post-operative audiograms, for cases of surgically treated otosclerosis with malleostapedotomy.ResultsTwelve patients underwent malleostapedotomy for otosclerosis between 2011 and 2019. Amongst them there were 10 revision surgeries and 2 primary cases. 75% had incus long-process necrosis, 17% had epitympanic fixation and one had a history of incus transposition. Nine patients (75%) had closure of air-bone gap (ABG) of <10 dB (p < 0.001) and 11 (92%) had a threshold of 20 dB (p < 0.001). Mean pre-operative ABG was 31 dB (15 dB–55 dB), and mean post-operative ABG was 7 dB (0 dB–21 dB; p < 0.001). There was no sensorineural hearing loss nor any other post-operative complication.ConclusionsMalleostapedotomy is a safe and reliable technique, allowing an ABG closure comparable to conventional incus to vestibule prosthesis. It remains the preferred technique whenever the incus cannot be used.     

HAB/DBP 复合物修复骨缺损的实验研究

目的：研究羟基磷灰石人工骨（HAB）/异体脱矿骨粉（DBP）复合物修复骨缺损的效果，以期获得一种既具有传导性又具有骨诱导性的复合材料。方法：将HAB/DBP复合物、HAB、异体脱矿骨(DMB)植入兔桡骨中段骨缺损处，设置空白对照，在2、4、8、12周分别取材，观察新骨形成及骨缺损修复情况。结果：HAB/DBP组、DMB组2周时可见骨断端附近有大量软骨细胞聚集，并有少量基质形成。4周时，大量软骨细胞及少量骨小架。8周时，见大量骨小梁和层板状骨形成。12周见层板成熟骨组织和哈佛系统形成。其成骨能力及新骨生成量明显高于HAB组及空白组。结论：HAB/DBP复合物为一种既具有骨传导性又具有骨诱导性的骨缺损修复材料，具有与DMB同样的诱导骨生成的能力，可能成为一种具有临床应用前景的骨缺损及修复材料。     

羟基磷灰石涂层热处理晶化工艺研究

目的：通过热处理方法提高羟基磷灰石（HA）涂层的结晶度、使脱落的羟基得到恢复。方法：通过等离子喷涂和热处理试验，利用X射线衍射（XRD）和红外吸收光普分析等手段研究了热处理对羟基磷石涂层相组成的影响。结果：热处理可使涂层中的非晶相发生晶化，并使羟基得到恢复；随着热处理温度的提高，涂层的结晶度提高，α－TCP等热分解相逐步转变为羟基磷灰石。保温时间达到2小时后，延长保温时间并不能提高涂层的结晶工。结论：在大气环境下，涂层的最佳热处理工艺是在700℃下保温2小时。     

Characterisation of enamel white spot lesions using X-ray micro-tomography

OBJECTIVES: The aim of this study was to characterise the mineral density (MD) of natural enamel white spot lesions (WSLs) using X-ray micro-tomography calibrated with different density hydroxyapatite phantoms. METHODS: Seven natural WSLs from four extracted non-carious premolar teeth were scanned at a voxel size of 7.6 microm using a desktop X-ray micro-tomography system. Five hydroxyapatite phantoms (sintered pellets of hydroxyapatite powder) with densities ranging from 1.52 to 3.14 g/cm(3) were used as calibration standards for each scan. Three-dimensional image reconstruction enabled MD gradients throughout the lesion to be quantified using an MD calibration equation derived from hydroxyapatite phantoms. Background noise generated during the measurement of MD was reduced using a Gaussian filter. RESULTS: Gaussian filter reduced the signal-to-noise ratio (standard deviation) significantly while the basic MD information (average value) remained intact. The mineral gradients through the WSLs examined were compared and are discussed in terms of existing literature. The MD of sound enamel, apparent intact surface layer of WSL, and lowest level of WSL was found to be 2.65-2.89 g/cm(3), 2.23-2.58 g/cm(3) and 1.48-2.03 g/cm(3), respectively. Our MD results are comparable with other studies. CONCLUSIONS: X-ray micro-tomography is a sensitive in vitro technique capable of characterising and quantifying MD of small non-cavitated WSLs. This method has a promising potential for future carious and quantitative remineralisation studies.     

Solubility of hydroxyapatite by solid titration at pH 3-4

OBJECTIVES: The solubility isotherm (S) of hydroxyapatite (HAp) is of fundamental importance to saliva chemistry, dental caries and related contexts. It has previously been shown that the locus of the S[HAp] is substantially lower than is commonly reported, and of different slope, probably due to HAps incongruent dissolution. The aim of the present study was to determine the S[HAp] over a wider pH range and to identify the precipitate formed at equilibrium in HAp solid titration. METHODS: The solid titration technique of Leung and Darvell (Leung VW-H, Darvell BW. Calcium-phosphate system in saliva-like media. J Chem Soc Faraday Trans 1991;87(11):1759-64.) was used to investigate the solubility behaviour of HAp at 37.0+/-0.1 degrees C in 100 mM aqueous KCl. The pH range studied overlapped that of earlier work from pH 3.6 to 5.2, for a reproducibility check and validation, and extended to pH approximately 2.9. XRD and EDX were used to identify the precipitates. SEM and TEM were used to observe the morphology. RESULTS: The previous S[HAp] reported by Chen et al. (Chen Z-F, Darvell BW, Leung VW-H. Hydroxyapatite solubility in simple inorganic solutions. Arch Oral Biol 2004;49(5):359-67.) was reconfirmed. An abrupt change of slope of S[HAp] was detected at pH approximately 3.9. No other phase than HAp was found at pH 3.2, 3.6 and 4.1. In particular, brushite (dicalcium phosphate dihydrate) was not detected, even below pH 3.9, where instead calcium-deficient HAp was formed. CONCLUSION: The solid titration method was reconfirmed as reproducible and to yield HAp from pH 2.9 to 5.2. The expected brushite did not appear, but rather a stable calcium-deficient HAp was consistently formed. The chemistry of calcium phosphates needs to be reevaluated.     

羟基磷灰石微晶体对培养骨细胞钙代谢的作用

通过体外研究，观察了三种不同浓度的羟基磷灰石（HA）微晶体悬液对骨细胞的钙代谢作用的影响。MC3T3-E1细胞和ROS细胞分别与1.5mg/ml,3.0mg/ml和4.5mg/ml的HA微晶体悬液混合培养，观察细胞的生长率。结果表明：中，低浓度的HA没有明显的细胞生长抑制作用，但高浓度的HA微晶体悬液有轻微的细胞生长抑制。各实验组的细胞内钙和细胞外钙的测定结果表明，细胞内外钙含量的变化与HA微晶体悬液的浓度有关，HA微晶体能直接作用于骨细胞的钙代谢，促进细胞的矿化作用。     

类骨质羟基磷灰石修复骨缺损的实验研究

目的:了解类骨质羟基磷灰石(OHA)的生物相容性,初步探讨其作为骨替代材料的可行性。方法:12只新西兰白兔随机分为4组,在双侧股骨内侧髁形成9mm×4mm×5mm大小的缺损,分别植入OHA和对照材料,术后2、4、8、12周取标本,进行大体标本、X线、组织学切片、扫描电镜观察及成骨面积的定量分析。结果:实验组成骨细胞易于粘附、生长、增殖,骨小梁形成钙化早,新骨面积百分比高于对照组,差异有统计学意义。结论:类骨质羟基磷灰石是一种良好的骨替代材料,具有广阔的应用前景。     

钛种植体-羟基磷灰石复合型植入体修复下颌骨缺损的动物实验

本研究采用钛种植体-羟基磷友石复合型植入体植入20只狗下颌骨牙缺失区．并对植入体与宿主骨结合的过程进行了X线、组织形态学观察和复合型植入体抗折强度测试。结果表明：术后12周．复合型植入体的抗折强度比植入体内前高；复合型植入体植入后用微型钛夹板固定组与宿主骨呈骨性结合；用骨膜复位缝合固定组与宿主骨呈纤维骨性结舍。钛种植体与羟基磷灰结合牢固．负荷条件下无松脱落。复合型植入体不干扰骨愈合过程。作者认为该种复合型植入体可用于颌骨缺损后的牙颌整复．但植入体植入后早期的稳定固定则十分重要。     

An optimized synthetic substrate for orthodontic bond strength testing

OBJECTIVE: The purpose of this study was to investigate the suitability of different synthetic calcium phosphate based substrates as a biomimetic enamel surface model for orthodontic bond strength testing. METHODS: Carbonated apatite, amorphous calcium phosphate and commercial hydroxyapatite specimens were prepared as substrates for orthodontic bond strength testing. Carbonated apatite specimens were prepared by pressing, sintering and treatment with NaF. The shear bond strength was measured with a universal testing machine. RESULTS: Hydroxyapatite, amorphous and cold pressed carbonated hydroxyapatite exhibited fractures within the substrate after debonding. Mean bond strength values for carbonated hydroxyapatite were 7.38 (1.75) MPa for specimens pressed at 300 degrees C and 9.55 (2.23) MPa for specimens pressed at 300 degrees C and then sintered at 600 degrees C. An additional NaF treatment after sintering resulted in lower bond strength measurements of on average 6.52 (1.03) MPa. SIGNIFICANCE: Hot pressed and sintered carbonated hydroxyapatite showed acceptable shear bond strength values and may represent a suitable biomimetic model for orthodontic bond strength testing.     

两种抗肿瘤药物影响生物陶瓷人工骨与骨结合的研究

为了探讨抗肿瘤药平阳霉素(BLM)及氨甲喋呤(MTX)对生物陶瓷人工骨与骨结合的作用,作者以杂种狗为种植模型,采用定量组织测量学、生物力学、元素分析的定量分析方法考察了骨与人工骨的结合区.结果发现在植入后1.5月MTX不仅能抑制局部新骨的生长与钙化,而且能减少骨与人工骨的结合,从而降低了人工骨植入体的稳定性.而同期BLM上述作用却不明显,因此作者认为对于肿瘤术后人工骨修复的患者的术后化疗拟应用BLM为宜.