Post-orthodontic cephalometric variations in bimaxillary protrusion cases managed by premolar extraction - A retrospective study.

BACKGROUND: Bimaxillary protrusion is a common dentofacial condition associated with proclination of maxillary and mandibular incisors in relation to the dental and cranial bases resulting in soft tissue procumbency. The present retrospective study aimed to investigate dental and soft tissue profile changes using cephalometric analysis to evaluate bimaxillary protrusion patients after extraction of the first four premolars and subsequent retraction of the anterior teeth. MATERIALS AND METHODS: Pre-treatment and post-treatment cephalometric radiographs of 46 Saudi patients (16 males and 30 females), 18-30 years of age with bimaxillary protrusion, were selected based on inclusion criteria. Dental and soft tissue landmarks were traced using the Dolphin® imaging software and statistically analyzed with SPSS® 21 software. RESULTS: The upper and lower incisors retroclined by a mean value of 9.6° and 9.65°, respectively, and an average distance of 4.1 mm. The level of maxillary incisor exposure was reduced by approximately 1.1 mm after treatment. A mean increase of 6.6° in the nasolabial angle was also observed. Multiple regression analysis showed that retraction of both upper and lower incisors by 1 mm would result in a 0.44 mm retraction of the upper and lower lips. CONCLUSION: A statistically significant increase in the nasolabial angle and upper lip length was found in relation to upper and lower incisor retraction and retroclination. A significant reduction was also evident in the post treatment upper incisor exposure, facial convexity angle and mentolabial sulcus depth.

Microbiochemical analysis of carious dentine using Raman and fluorescence spectroscopy.

The aim of this study was to evaluate and correlate objectively the microspectroscopically derived biochemical components of sound, infected and affected carious dentine with their microhardness and autofluorescence (AF) characteristics. Over 3 million high-resolution Raman spectra from 8 extracted human carious teeth were recorded using Raman spectrometer with parallel spectrum acquisition. Green AF signals across each carious lesion from all samples were acquired with a similar spatial resolution using confocal fluorescence microscopy. The Knoop microhardness (KHN) from a total of 233 co-localized areas was recorded from the same samples and allocated subjectively into the three zones. Cluster analysis of the Raman data, performed using in-house software, produced five independent spectral components representing mineral content, protein content, porphyrin fluorescence (PF), putative infected dentine signal (IDS) and affected dentine signal (ADS). The distributions of the 5 Raman components and the AF signal were matched across all samples and their average values were calculated for each corresponding KHN area. The infected dentine was defined significantly by the KHN, AF and by the relative contribution of the mineral, PF and IDS clusters. Protein cluster was not statistically related to the KHN or AF. A delineation between affected and sound dentine was observed using the KHN, AF, PF and ADS parameters. This study concludes that micro-Raman spectroscopy can provide a non-invasive and objective evaluation of different carious dentine zones. Being able to detect and assess clinically the caries-affected dentine during minimally invasive operative caries management is important to control the risk of unnecessary tissue removal.

Effects of MMP inhibitors incorporated within dental adhesives.

Matrix metalloproteinase (MMP) inhibition has been shown to reduce adhesive bond degradation when applied as a pre-conditioner, adding to clinical steps in the placement of adhesives, but their incorporation within dental adhesives has not been fully explored. This study examined the effect of including 2 MMP inhibitors (BB94 and GM6001) within the primers of 3 commercially available adhesives. Fluorometric assay and zymography showed that adhesives with MMP inhibitors had high affinity toward both synthetic fluorogenic FRET peptides (95%) and dentin powder substrates, respectively. The immediate microtensile bond strength was enhanced for 2 types of adhesives following the addition of both inhibitors. However, no changes were detected between the control and the inhibitor groups following 3-month storage. The modified two-step etch-and-rinse and single-step systems showed less Rhodamine B penetration to the "hybrid layer" and to the "adhesive", respectively. The incorporation of BB94 and GM6001 within the primers resulted in the inhibition of dentin MMPs with improved initial bond strength and enhanced sealing ability.