Enhancing Student Learning of Removable Prosthodontics Using the Latest Advancements in Virtual 3D Modeling

When educating dental students or prosthodontic residents, a picture can be worth a thousand words. If that is so, then what could enhanced 3D modeling be worth relative to enhancing student learning? The answer is undoubtedly more than what a picture can provide. That is why the use of 3D models has become increasingly common with respect to patient care. The 3D modeling allows the patient to visualize more clearly the proposed treatments and outcomes; however, while 3D modeling has started to make an appearance in dental education, many of the current 3D modeling techniques do not offer the flexibility needed for dental education and enhanced student learning. At the University of Iowa, the use of 3D modeling software has enabled the creation of 3D models that can be altered or customized to be used in a more flexible way to teach students in the arts and complexities of removable partial denture (RPD) design and associated components. This educational technique article will: (1) demonstrate how these 3D models can be used to enhance student perception and learning regarding RPDs; and (2) will demonstrate using videos and web‐based portals to show how the 3D RPD models were created and then used for educational purposes.     

Deformation and retentive force following in vitro cyclic fatigue of cobalt-chrome and aryl ketone polymer (AKP) clasps

ObjectiveTo compare the retention force of individual clasps made from cobalt chromium (CoCr) or new aryl ketone polymer (AKP) material, Ultaire™ AKP, following prolonged fatigue testing along ideal and non-ideal paths of removal and to assess 3D deformation of the active and passive clasp tips.MethodsCoCr and AKP clasps were manufactured in their standard, respective processes, digitally scanned prior to testing, then cycled 15,000 times over an e.max analogue crown in artificial saliva. Retentive load was measured in situ, as a function of cycles. Clasps were rescanned to assess deformation and along with their antagonists subjected to SEM to assess localised wear.ResultsDistortion of the CoCr clasps was consistently larger than Ultaire™ AKP clasps, irrespective of removal path. CoCr clasps had significantly higher retentive forces than AKP clasps, for both removal paths. Ultaire™ AKP clasps showed a lower but relatively constant retentive force. The non-ideal path of removal affected retentive forces for both clasp materials. SEM showed localised removal of glaze for e.max crowns used with CoCr clasps.SignificanceUltaire™ AKP clasps showed significantly less permanent deformation and lower retentive force than CoCr clasps. Unlike CoCr, the Ultaire™ AKP clasps did not work harden, nor had as large a reduction in retentive force and accompanying permanent deformation; the retentive force for the Ultaire™ AKP clasps was consistent over 15,000 cycles of fatigue mimicking prolonged clinical use. The AKP material was more robust; showing minimal deformation even in non-ideal paths of removal, as many patients would routinely use.     

Evidences for the regulation of GnRH and GTH expression by GnIH in the goldfish, Carassius auratus

Gonadotrophin-inhibitory hormone (GnIH) plays an important role in regulating of reproduction in teleosts. To clarify the mode of action of GnIH on the synthesis of gonadotropin releasing hormone (GnRH) and gonadotrophin (GtH), three GnIHR cDNAs were cloned from the goldfish brain. In situ hybridization results showed that GnIHRs were localized to the hypothalamus and pituitary. In the hypothalamus, GnIHRs were found in the NPP, NPO and NLT, whereas sGnRH neurons were reported to be located, and potentially regulated by GnIH. In the pituitary, only two GnIHRs were observed and they were localized to the PI instead of the adenohypophysis where GtH-expressing cells are localized, suggesting indirect regulation of GtH by GnIH. In vivo, intraperitoneal (i.p.) injections of synthetic goldfish GnIH-II peptide and GnIH-III peptide significantly decreased sGnRH and FSHβ mRNA levels. Only GnIH-II decreased LHβ mRNA levels significantly. In vitro, both GnIH-II and GnIH-III showed no effect on GtH synthesis, but an inhibition of GnRH-stimulated LHβ and FSHβ synthesis was observed when GnIH-III was applied to primary pituitary cells in culture. Thus, GnIH could contribute to the regulation of gonadotropin in the brain and pituitary in teleosts.     

可摘局部义齿三维几何学模型库的应用

目的 探讨可摘局部义齿修复体模型库的应用方法。方法 借助PRO／E,POWERSHAPE等软件,合理设计模型库的结构,并探讨快速高效的使用方法。结果 模型库可通过“调用－编辑”和“单元组”的方法应用。结论 该模型库有较合理的组成结构,应用高效,快速。     

在线近红外光谱监测桂枝茯苓胶囊流化床干燥过程水分的方法研究

目的采用在线近红外光谱(NIRS)技术,建立桂枝茯苓胶囊流化床干燥过程水分实时监测模型。方法通过NIRS漫反射探头采集16个生产批次共176个样本进行建模,优选移动窗口平滑法进行光谱预处理,采用间隔偏最小二乘法(si PLS)结合移动窗口偏最小二乘法(mw PLS)筛选特征变量为4 759.45～5 338.00 cm-1、5 503.84～6 101.67 cm-1、8 512.25～8 809.24cm-1,采用偏最小二乘(PLS)法建立水分含量多变量校正模型。结果水分预测的交叉验证均方根误差(RMSECV)为0.243%,性能偏差比(RPD)值为13.384,预测相对偏差(RSEP)为0.270%。以8个生产批次对在线监控方法的可靠性进行持续验证,结果 40个样本的相对预测误差均小于4.7%。干燥过程水分实时监测趋势图显示可准确判断干燥终点,终点样本水分含量位于控制限内。结论在线NIRS结合PLS建立的定量模型,可应用于生产规模桂枝茯苓胶囊流化床干燥过程水分含量在线监控且预测性能稳健、准确。     

Full mouth rehabilitation of destroyed dentition with rotational path removable partial denture: a case report

BACKGROUND

Though implant dentistry is very successful and predictable in treatment of patients with destroyed dentition, there are some cases with limitations to implant therapy. In these cases, alternative treatment modality should be considered.

CASE DESCRIPTION

A patient with destroyed dentition was rehabilitated with a lateral rotational path removable partial denture. According to the diagnosis, we determined to raise vertical dimension for esthetic and functional restoration. The final restoration was performed after four months of provisional period.

CLINICAL IMPLICATION

The edentulous patients with compromised esthetics and functions can be successfully treated with a rotational path removable partial denture through adequate treatment planning and precise laboratory procedure.     

RPD3 (REC3) mutations affect mitotic recombination in Saccharomyces cerevisiae

Prior research identified the recessive rec3-1ts mutation in Saccharomyces cerevisiae which, in homozygous diploid cells, confers a conditional phenotype resulting in reduced levels of spontaneous mitotic recombination and loss of sporulation at the restrictive temperature of 36 °C. We found that a 3.4-kb genomic fragment that complements the rec3-1ts/rec3-1ts mutation and which maps to chromosome XIV, is identical to RPD3, a gene encoding a histone de-acetylase. Sporulation is reduced in homozygous diploid strains containing the rec3-1ts allele at 24 °C, suggesting that this allele of RPD3 encodes a gene product with a reduced function. Sporulation is abolished in diploid strains homozygous for the rpd3Δ or rec3-1ts alleles, as well as in rpd3Δ/rec3-1ts heteroallelic diploids, at the non-permissive temperature. Acid-phosphatase expression has been shown to be RPD3 dependent. We found that acid-phosphatase activity is greater in diploid strains homozygous for the temperature-sensitive rec3-1ts allele than in RPD3/RPD3 strains and increased further when mutant strains are grown at 36 °C. We also tested the rpd3Δ/rpd3Δ strains for their effects on spontaneous mitotic recombination. By assaying a variety of intra- and inter-genic recombination events distributed over three chromosomes, we found that in the majority of cases spontaneous mitotic recombination was reduced in diploid rpd3Δ/rpd3Δ cells (relative to a RPD3/RPD3 control). Finally, although 90% of mitotic recombinant events are initiated in the G₁ phase of the growth cycle (i.e., before DNA synthesis) we show that RPD3 is not regulated in a cell-cycle-dependent manner. These data suggest that mitotic recombination, in addition to gene expression, is affected by changes in chromatin architecture mediated by RPD3. Received: 17 July / 30 November 1998