The effects of incremental brightness and contrast adjustments on radiographic data: A quantitative study

PubMed ID: 15709101Objectives: To determine the border level of brightness and contrast changes in order to prevent the loss of originality of the quantitative data on digital dental radiographs. Methods: After measuring the baseline mean grey values (MGVs) of a fixed region of interest on the alveolar bone and an aluminium step wedge, incremental brightness and contrast adjustments were performed on a digital periapical radiograph. The distribution of the data was analysed to investigate the significance of the changes on radiodensitometric data after incremental increase of brightness and contrast. Results: The original MGVs were easily retrieved after brightness adjustments; however, the contrast increase led to more complicated density changes. The originality of the data was saved up to 50 units of contrast increase, but further than this limit, significant radiodensitometric changes occurred. Conclusions: Contrast adjustments should be performed cautiously when making quantitative analyses on the digital radiographs. © 2005 The British Institute of Radiology

The talon cusp – an uncommon anomaly

Talon cusps are an uncommon dental anomaly of odontogenic origin. Talon cusps can also present with other dental anomalies, however these have been infrequently reported in the literature.The following is a report of two cases in which talon cusps were detected in combination with two distinct dental anomalies: an ectopic canine and transposition.</p

Histomicrobiologic aspects of the root canal system and periapical lesions in dogs' teeth after rotary instrumentation and intracanal dressing with Ca(OH)2 pastes Aspectos histomicrobiológicos do sistema de canais radiculares e das lesões periapicais em dentes de cães após instrumentação automatizada e medicação intracanal com pastas de Ca(OH)2

OBJECTIVE: The purpose of this study was to evaluate the distribution of microorganisms in the root canal system (RCS) and periapical lesions of dogs' teeth after rotary instrumentation and placement of different calcium hydroxide [Ca(OH)2]-based intracanal dressings. MATERIALS AND METHODS: Chronic periapical lesions were experimentally induced in 80 premolar roots of four dogs. Instrumentation was undertaken using the ProFile rotary system and irrigation with 5.25% sodium hypochlorite. The following Ca(OH)2-based pastes were applied for 21 days: group 1 - Calen (n=18); group 2 - Calen+CPMC (n=20); group 3 - Ca(OH)2 p.a. + anaesthetic solution (n=16) and group 4 - Ca(OH)2 p.a.+ 2% chlorhexidine digluconate (n=18). Eight root canals without endodontic treatment constituted the control group. Histological sections were obtained and stained with Brown & Brenn staining technique to evaluate the presence of microorganisms in the main root canal, ramifications of the apical delta and secondary canals, apical cementoplasts, dentinal tubules, areas of cemental resorption and periapical lesions. The results were analyzed statistically by the Mann-Whitney U test (p<0.05). RESULTS: The control group showed the highest prevalence of microorganisms in all sites evaluated. Gram-positive cocci, bacilli and filaments were the most frequent morphotypes. Similar microbial distribution patterns in the RCS and areas of cementum resorption were observed in all groups (p>0.05). The percentage of RCS sites containing microorganisms in groups 1, 2, 3, 4 and control were: 67.6%, 62.5%, 78.2%, 62.0% and 87.6%, respectively. CONCLUSION: In conclusion, the histomicrobiological analysis showed that the rotary instrumentation and the different calcium hydroxide pastes employed did not effectively eliminate the infection from the RCS and periapical lesions. However, several bacteria seen in the histological sections were probably dead or were inactivated by the biomechanical preparation and calcium hydroxide-based intracanal dressing.<br>OBJETIVO: Neste estudo avaliou-se a distribuição dos microrganismos no sistema de canais radiculares (SCR) e região periapical (RP) de cães após instrumentação automatizada e utilização de pastas à base de hidróxido de cálcio CaO(H)2. MATERIAL E MÉTODOS: Lesões periapicais crônicas foram induzidas em 80 raízes de pré-molares de quatro cães. Após a instrumentação com o sistema Profile auxiliado pela solução de hipoclorito de sódio a 5,25%, aplicou-se as seguintes pastas contendo Ca(OH)2: grupo 1-Calen (n=18), grupo 2-Calen/PMCC (n=20), grupo 3-hidróxido de cálcio p.a. + solução anestésica (n=16) e grupo 4-hidróxido de cálcio p.a. + solução de digluconato de clorexidina a 2% (n=18), por 21 dias. Oito canais radiculares sem tratamento endodôntico constituíram o grupo-controle. Nas secções histológicas coradas por Brown & Brenn, avaliou-se a presença de microrganismos nos 3mm apicais do SCR e RP, incluindo o canal radicular principal, deltas, cementoplastos, túbulos dentinários, reabsorções cementárias e lesão periapical. Os resultados foram analisados pelo teste de Mann-Whitney (p<0.05). RESULTADOS: Verificou-se que o grupo-controle apresentou a maior freqüência de microrganismos em todos os sítios, com nítida presença de biofilmes nas paredes do canal radicular e nas reabsorções cementárias. Cocos, bacilos e filamentosos foram os morfotipos mais frequentes. Similar padrão de distribuição de microrganismos foi observado no SCR e nas áreas reabsorções sementárias de todos os grupos (p>0.05). Nos grupos 1, 2, 3, 4 e controle, os percentuais de sítios do SCR contendo microrganismos foram: 67.6%, 62.5%, 78.2%, 62.0% e 87.6%, respectivamente. CONCLUSÃO: Histomicrobiologicamente, os protocolos de anti-sepsia utilizados proporcionaram insignificativa redução dos microrganismos no SCR e na RP, embora, metabolicamente, muitas bactérias vistas nas secções histológicas podem ter sido inativadas irreversivelmente ou mesmo perdido a viabilidade em função dos procedimentos de anti-sepsia utilizados