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open access
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ISSN : 0376-4672
Purpose : The purpose of this study is to compare flexural strength according to the thickness of provisional restoration materials manufactured by subtractive and additive methods using CAD-CAM system. Materials and methods : It was divided into three groups with different manufacturing methods, the CON group manu factured by the traditional method, the MIL group manufactured by subtractive methods and the DLP group manufactured by additive methods. Each group was divided into 3 groups by varying the thickness of the specimen (1.0 mm, 1.5 mm, 2.0 mm), and a total of 9 experimental groups were set. Fifteen specimens for each group were prepared in the form of a bar and the flexural strength was measured. Results : According to the manufacturing method, the MIL group showed the highest flexural strength, followed by the DLP group and the CON group(p<0.01). In the MIL and DLP groups, the flexural strength increased statistically significant ly as the thickness increased (p<0.01), but in the CON group, there was no statistically significant difference in the flexural strength at 1.5 mm thickness and 2.0 mm thickness(p>0.05). Conclusion : Provisional restorative resins fabricated by subtractive methods showed higher flexural strength than those made by additive manufacturing, and both showed superior flexural strength than those fabricated by traditional methods. Active use of the CAD-CAM system in the dental field is recommended, however, as the flexural strength decreases sta tistically as the thickness of the material decreases, we need to be careful about reduction in the thickness of the material.
Purpose : The purpose of this study was to compare the wettability of 4 type of denture relining materials by measuring contact angle with saliva substitute. Materials and methods : Heat-cured reline resin(Vertex RS), Self-cured reline resin(Probase Cold, Tokuyama Rebase Ⅱ), soft liner(COE Soft) were fabricated as specimens. Before and after storage in saliva substitute for 24 hour, contact angle between specimens and CMC based saliva substitute(Xerova soln) were measured. Contact angle according to denture relining materials were analyzed by one-way ANOVA and Tukey test(α=0.05). Con tact angle before and after storage in saliva substitute were analyzed by independent t test(α=0.05). Results : Before storage, Rebase Ⅱ showed significantly lower cont859623act angle compared to Vertex RS, Probase Cold, COE Soft(P<0.05) and COE Soft showed significantly higher contact angle compared to Vertex RS, Probase Cold, Rebase Ⅱ(P<0.05). After storage, Rebase Ⅱ showed significantly lower contact angle compared to Vertex RS, COE Soft(P<0.05) and COE Soft showed significantly higher contact angle compared to Vertex RS, Probase Cold, Rebase Ⅱ(P<0.05). Before and after storage, Rebase Ⅱ and COE Soft showed significant difference(P<0.05). Conclusion : Before and after storage in saliva substitute for 24 hour, the contact angle was highest in the order of Rebase II, Probase Cold, Vertex RS, and COE Soft. After storage in saliva substitute for 24 hour, the contact angle of Rebase II and COE Soft changed, but Vertex RS and Probase Cold did not change.
The oral microenvironment can be modulated by chronic exposure to microorganisms, their byproduct and host-derived inflammatory response. Recently, high-risk HPV has been reported in periodontitis patients, suggesting that periodontal disease may be a reservoir for high-risk human papillomavirus (HPV). We aimed to examine the relationship between the existence of high-risk HPV 16/18 and the severity of periodontal disease. We collected a total of 342 oral specimens from 20 healthy subjects and 37 periodontitis patients. The specimens included dental plaque, saliva, and tongue scrape samples. HPV 16 or 18 (high-risk HPV) were detected by real time PCR. The data showed that high-risk HPV in healthy, stage I (mild) periodontitis and stage II (moderate) to stage III/IV (severe) periodontitis were 1.75% (6/342), 2.92% (10/342), and 8.47% (29/342), respectively. Dental plaque and tongue scrape specimens from moderate and severe periodontitis patients showed a significant detection of high-risk HPV in comparison with specimens collected from mild periodontitis and healthy subjects (p<0.01). Collectively, the severity of periodontal disease significantly increased the odds of high-risk HPV-positive samples (p<0.01). Our data suggest that the presence of HPV 16 and 18 in plaque and tongue of periodontitis patient may provide a suitable ecosystem for high-risk HPV.
Recently, with the development of information science and technology, data has exploded in various fields, and big data is being analyzed and interpreted in each field and widely used. Although the use of artificial intelligence (AI) in oral pathology is still in its infancy, many attempts are being made to diagnose and evaluate through automated image analysis after using a slide scanner to store the whole histopathologic slides as a digital image. In particular, in the field of oral cancer diagnosis, attempts are being made to increase accuracy by adding meaningful information such as clinical characteristics and radiologic images to these digital images to enable more accurate diagnosis through analysis and processing. In this paper, we will discuss the current uses, limitations, and future roles of AI in oral pathology.
The philosophy of medicine by Georges Canguilhem, who wrote The Normal and the Pathological, defined pathology as the study that precedes physiology and deals with another norm of life. The debate behind the con tinuous reclassification of odontogenic keratocyst(OKC) is appropriate example for Canguilhem’s definition. In this paper, we will examine medical and dental cases important at the clinic, especially OKC, and discuss its hidden meanings with a Canguilhem’s point of view.