Three-dimensional stereophotogrammetric analysis of 50 smiles: A study of dento-facial proportions.

OBJECTIVES: The purpose of this study was to analyze 50 smiles using 3D stereophotogrammetry (3D-spg)-based facial reconstruction, to calculate ratios involving measurements of the distances between dental and facial landmarks and to compare these ratios with the golden ratio φ (1.618). MATERIALS AND METHODS: Fifty subjects with no obvious malocclusion participated in this study. For each subject, 4 photographs were acquired using the LifeViz Mini™, an absolute calibration 3D-spg system. Facial and dental landmarks (based on Farkas' definitions) were fixed, and 8 distances were measured. Four ratios were then calculated and compared with the value of 1.618. RESULTS: The ratio "incisal edge of the maxillary central incisor-lower border of the chin/subnasal point-incisal edge of the maxillary central incisor" (IE-Me/SN-IE) was 1.693 ± 0.190, the ratio "right endocanthion-left endocanthion/right exocanthion-right endocanthion" was 1.582 ± 0.173, the ratio "incisal edge of the maxillary central incisor-distal edge of the right canine/distal edge of the right canine-right labial commissure" was 1.670 ± 0.355, and the ratio "right labial commissure-left labial commissure/distal edge of the right canine-distal edge of the left canine" was 1.602 ± 0.136. In contrast, the vertical ratio IE-Me/SN-IE significantly differed from the golden ratio (1 sample t test, P = .009). CONCLUSION: This study revealed that the observed ratios were surprisingly close to the golden ratio. Only the vertical ratio differed from the golden ratio, whereas the horizontal ratios appear to be adequately approximated by φ. CLINICAL SIGNIFICANCE: If the distances from reference points of the face to teeth within a harmonious smile exhibited recurring esthetic proportions, knowledge of such ratios would provide an additional tool for the elaboration of esthetic treatment plans. In addition, this knowledge could provide guidance when planning tooth positions and dental proportions by encouraging consideration of the global nature of the oro-facial sphere.

Comparison of microleakages of photo-cured composites using three different light sources: halogen lamp, LED and argon laser: an in vitro study.

In this study, we compared the microleakage of composite fillings cured with halogen bulb, LED and argon ion laser (488 nm). Twenty-four extracted human molars were divided randomly in three groups. Six cavities were prepared on the coronal part of each tooth. Standard cavities (1.7 x 2 mm) were prepared. Cavities were acid etched, sealed with Scotch Bond 1 and filled by a hybrid composite. Cavities were exposed to one light source, thermocycled and immersed in a 2% methylene blue dye solution. Dye penetration in the leakage of cavities was recorded using a digital optical microscope. Mean values of percentage of dye penetrations in microleakages of cavities were 49.303 +/- 5.178% for cavities cured with LED, 44.486 +/- 6.075% with halogen bulb and 36.647 +/- 5.936% for those cured by argon laser. Statistically significant difference exists between cavities cured by halogen vs LED (P < 0.01), halogen vs laser (P < 0.001) and LED vs laser (P < 0.001). The lowest microleakage was observed in the cavities and composites cured with argon ion laser.

Nd:YAG and diode laser in the surgical management of soft tissues related to orthodontic treatment.

OBJECTIVE: The aim of this clinical study was to observe and evaluate the surgical management efficiency of soft tissues during orthodontic treatment. MATERIALS AND METHODS: Thirty-seven young patients were selected and treated by laser-assisted surgery before or during orthodontic treatment and were classified by sex, age, and type of surgical management. Three different wavelengths were used (diode 810 nm, diode 980 nm, and Nd:YAG 1064 nm) in different surgical situations: maxillary vestibular and lingual frenectomies, surgical exposure and alignment of ectopic or retained teeth, and re-contouring gingival overgrowth. RESULTS: In all evaluated patients, the laser treatment was performed without local anesthesia or sutures. Only topical anesthetic was needed. CONCLUSION: These use of these wavelengths of laser energy was a noticeable aid in the surgical management of soft tissues before or during orthodontic treatment. The benefits of laser treatment include reduced bleeding during surgery with consequent reduced operating time and rapid postoperative hemostasis, thus eliminating the need for sutures. The lack of need for anesthetics and sutures, as well as improved postoperative comfort and healing, make this technique particularly useful for very young patients.

Manual toothbrush wear and consequences on plaque removal.

OBJECTIVE: The aim of this study was to determine the mean time interval before needing to discard different types of manual toothbrushes based on wear, and on the impact of progressive wear on plaque removal efficacy. METHODOLOGY: Two cross-over randomized clinical trials involving the same 12 volunteers tested four toothbrushes of different designs. In Study 1, the brushes were the Butler 211 (BTB) and Fluocaril Sensia (FSTB). In Study 2, the brushes were Elmex InterX (ETB) and Elgydium Interactive (ELTB). In both trials, the volunteers randomly used one of the two toothbrushes for two minutes twice a day during the first week, and the other brush during the following week, and continued this alternating routine for two months. An image acquisition system and the Visilog 5.2 image analysis program were used to calculate the wear index (WI) after one and two months of use for each toothbrush. The OHI-S plaque index (PI) was recorded after one and three minutes of tooth brushing at one and two months. The Friedman or Kruskal-Wallis test was used to compare data. RESULTS: Except for the ELTB, the wear of the toothbrushes was greater during the first month of brushing than during the second. The total WI was FSTB 35.46 (range = 62.11), ELTB 30.14 (range = 67.92), ETB 48.77 (range = 123.87), and BTB 98.20 (range = 134.75). The differences were significant at p = 0.008. The post one-minute PI scores significantly increased with wear, except in the case of ELTB (p = 0.244). When comparing all toothbrushes' PI at the one and three-minute tooth brushing times, there were significant differences at one month among them at p < 0.0001. CONCLUSION: The amount of wear depended on the toothbrush design. It was greater for rectangular tooth brushing areas or when bristles had smaller diameters and different heights. With two-month-old toothbrushes, plaque removal was better when there was less measurable wear.

Embolization-driven occlusion of the abdominal aortic aneurysmal sac as the basis of prevention of endoleaks in a new swine model.

OBJECTIVES: To assess the effect of a new polymer in embolization of endoleaks using an animal model. METHODS: A modified aortic stent-graft was placed in 20 pigs. Embolization was performed at the time of graft insertion with non-cytotoxic n-butyl-2-cyanoacrylate-metacryloxysulpholane and lipiodol (0.2:0.8ratio, 2 ml). Angiography, scanning electron microscopy and immuno-histochemistry were obtained at day 0, 1 week and 3 months. RESULTS: In control animals both type I and II endoleaks were demonstrated. In treated animals, neither type-I nor type-II endoleaks were observed and a fibro-proliferative response was demonstrated within the aneurysm thrombus. CONCLUSIONS: Host vascular responses govern the fate of the excluded aneurysm. Embolization of the sac and feeding arteries with non-cytotoxic glue sealed all occlusions by stimulating a massive restenosis-like process.

Effect of sono-abrasion in the microleakage of a pit and fissure sealant.

PURPOSE: To assess the microleakage of a pit and fissure sealant after preparing enamel with sono-abrasion, used alone or associated with acid etching. This technique was compared with classical enamel preparations i.e. acid etching and diamond bur associated with etching. MATERIALS AND METHODS: Ninety 3rd molars were used. In the mesial halves, the fissures were prepared with sono-abrasion and acid etching for 15 seconds. Then, the samples were randomly assigned to three groups of 30. They were either treated with acid etching alone (group 1), widened mechanically with a bur and etched for 15 seconds (group 2) or prepared with sono-abrasion alone (group 3). Then, the resin-based sealant was applied according to the manufacturer's recommendations. The teeth were thermocycled and placed in a 1% solution of methylene blue. The teeth showing microleakage and the means of infiltration were assessed with an image analysis system. RESULTS: The poorest results were obtained with sono-abrasion alone which showed a greater number of specimens with microleakage (73.3%) (p < 0.001). They also showed the highest mean of microleakage (0.85+/-0.79 mm vs 0.1+/-0.26 for acid; 0.35+/-0.85 for bur associated with etching p < 0.0001); and 0.19+/-0.45 for sono-abrasion associated with etching. CONCLUSION: No significant difference was noted between the three types of enamel preparation using etching. Sono-abrasion can be used for preparing dental enamel prior to sealing the tooth but it does not eliminate the need for etching.

In vitro action of Bordeaux red wine on the microhardness of human dental enamel.

Several studies have demonstrated that the regular and large consumption of wine is associated with increased risk of tooth erosion. Here, the effect of Bordeaux red wine on enamel was estimated by measuring changes in its Vickers microhardness. Thirty premolars were used; microhardness tests were performed on buccal areas before and after 10, 30, 90 and 120 s immersion in the wine (pH=3.9). Enamel surfaces were also observed by scanning electron microscopy. No statistically significant difference was found between the mean Vickers microhardness obtained at t=0 and 90 s, but slight signs of enamel demineralisation were observed with the scanning electron microscope. It appears that wine has no disastrous effect on the microhardness of dental enamel when the two are in contact for less than 90 s. When the exposure is for at least 120 s, it may become harmful, as the decrease in the microhardness of enamel was then significant (P<0.05).

Periapical status, prevalence and quality of endodontic treatment in an adult French population.

AIM: The aim of this study was to determine the periapical status and the quality of root-canal treatment amongst an adult population attending the dental school in Nice, France during 1998. METHODOLOGY: Patients who attended the dental school for the first time during 1998 were included. Panoramic radiographs, taken by a trained radiology assistant, were used in this study. The periapical areas of all teeth with the exception of third molars, were examined and the technical quality of root fillings were evaluated for both apical extension and density. Statistical analyses were conducted using anova, Chi-square, Fisher's PLSD and Cohen's Kappa tests. RESULTS: The survey involved 344 patients: 180 females and 164 males. Males had significantly fewer natural remaining teeth than females (P<0.03). Similarly, the average number of root-filled teeth was lower for males (P<0.01). Nonroot-filled teeth (n=6126) had significantly fewer signs of periapical pathology than root-filled teeth (n=1429) (1.7% vs. 31.5%, P<0.0001). The majority of root fillings were poorly executed. There was a significant correlation between the presence of periapical pathology and inadequate root-canal fillings (P<0.001). CONCLUSIONS: The results of the present study indicate that many root-canal treatments were technically unsatisfactory in terms of quality and treatment outcome. There is a need for endodontic retreatment in the population examined.

Curved molar root canal preparations using Hero 642 rotary nickel-titanium instruments.

AIM: The Bramante method was used to study how the natural curvature of root canals was modified when using the Hero 642 nickel-titanium rotary system. METHODOLOGY: Twenty-four canals were selected in freshly extracted human mandibular molars. Every root canal had an angle of curvature greater than 20 degrees. Roots were embedded in clear casting resin using a plaster mould. Cross-sectional cuts were made in the apical, middle and coronal thirds of each root. A first group (control) of 12 curved root canals was prepared using stainless steel hand instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the Hero sequence according to the manufacturer's instructions. For each sectioning level, the amount of dentine removed, the change of shape factor and the canal centre displacement were calculated with the aid of a digital image analysis system. The results were subjected to the Mann-Whitney U-test. RESULTS: No significant difference occurred in the amount of dentine removed, change of shape factor or canal centre displacement in the coronal and middle thirds of the curved canals. In the apical third, transportation was significantly higher (P=0.0171) with stainless steel hand instruments than with the Hero system. CONCLUSIONS: The original canal shape was maintained better in the apical third of curved canals when using the Hero system in a crown-down technique when compared to a hand preparation technique with stainless steel instruments.

Effect of surface penetrating sealant on surface texture and microhardness of composite resins.

The application of Fortify (Bisco, Lombard, IL), an unfilled resin, to the surface of composite resin restorations is intended to fill in defects in the surface that persist despite polishing, improve marginal integrity, and increase these materials' resistance to abrasion. The aim of this study was to observe the surface texture by scanning electron microscopy and measure the microhardness of the surface. For each sample of composite resin covered with glaze, 40 measurements were made of the thickness of the resin. Measurements of the Vickers microhardness included three samples of composite resin, three samples of glaze, and six samples of composite resin covered with glaze. A relationship was established between microhardness and thickness. Scanning electron microscopy showed a noticeable improvement in the surface texture. Nevertheless, areas were seen in which glaze seemed very thin or even completely absent. Measurements of the thickness ranged from 0-70 microm. The mean microhardness of composite resin was 65.8 +/- 0.7, while the mean hardness of glaze was 7.3 +/- 0.7. The microhardness of the double layer was reduced, depending on the thickness of the glazing resin. The capacity of glaze to mask surface defects of composite resin was shown, but it was difficult to obtain a regular surface with liquid resin. The application of this product caused a decrease of the microhardness of the composite resin's surface.

The removal of the smear layer using the Quantec system. A study using the scanning electron microscope.

AIM: The aim of this study was to determine the ability of the Quantec Series 2000 rotary nickel-titanium endodontic system to remove dentinal debris and smear layer produced during canal preparation. METHODOLOGY: A first group (control) of 12 curved root canals was prepared using conventional manual instruments and the step-back technique. A second group of 12 curved root canals was instrumented using the complete Quantec sequence according to the manufacturer's instructions. In both groups, irrigation was performed using a 3% NaOCl solution. The canal walls were observed under a scanning electron microscope and the coronal, middle and apical thirds of each canal photographed at a magnification of 500. The views were divided into 10 subareas by overlaying a grid, and the absence or presence of a smear layer was rated and scored on three appearances using the scale described by Ciucchi et al. (1989). RESULTS: The scores were higher (i.e. less debris was present) in the middle third (P < 0.0001) and in the apical third (P < 0.0001) of canals prepared with the Quantec system when compared with those prepared with K-files. Nevertheless, in canals prepared with Quantec instruments, the scores were significantly higher in the coronal third compared with the apical third (P < 0.005). CONCLUSIONS: The Quantec rotary system produced cleaner canal walls than conventional manual instrumentation, particularly in the middle and apical thirds. This finding may imply that stresses applied to the cutting regions of Quantec instruments by accumulation and compression of the smear layer are minimized.

Comparative study of physical properties of three suture materials: silk, e-PTFE (Gore-Tex), and PLA/PGA (Vicryl).

The aim of this in-vitro study was to compare the physical properties of three suture materials used in periodontal surgery: silk, expanded polytetrafluoroethylene (e-PTFE), and polylactic acid/polyglycolic and (PLA/PGA). Five physical tests were carried out on each of the three suture materials: strain to failure, tensile strength, knot tensile strength, knot slippage, and capillarity. For each test, 30 samples of each suture material were used. In all cases, the statistical results showed that the e-PTFE and the PLA/PGA threads were superior.

Effect of cross-linkers on the structure and function of pig-renal sodium-glucose cotransporters after papain treatment.

Kidney brush-border membranes contain two sodium-dependent glucose transporters, one with low and one with high affinity for phlorizin, the specific inhibitor of these transporters. Using Scatchard analysis of phlorizin binding and Western blotting with specific antibodies against these transporters, we demonstrate in this study that although both transporters were proteolysed by papain treatment, only the high-affinity phlorizin-binding sites were decreased. Papain treatment followed by cross-linking with homobifunctional disuccinimidyl tartarate restored only the structure of the low-affinity phlorizin-binding protein (approx. molecular mass 70 kDa) without modifying the phlorizin-binding sites. When disuccinimidyl tartarate was replaced with dithiobis(succinimidyl acetate), another homobifunctional cross-linker with a higher spacer arm, the low- and high-affinity sites were both restored, with reappearance of two phlorizin-binding proteins with approx. molecular masses of 70 and 120 kDa. We conclude that high-affinity phlorizin-binding sites depend on the presence of the heterodimeric 120 kDa protein.

Removal of Thermafil root canal filling material.

The aim of this study was to evaluate if removal of Thermafil plastic carriers and reestablishment of working length were possible in single rooted teeth filled with the Thermafil system. Twenty freshly extracted maxillary central incisors were prepared and filled with #30 Thermafil plastic obturators according to manufacturer's recommendations. Teeth were divided in two groups: Group I: 10 teeth were retreated using dimethylformamide as a solvent. Group II: 10 teeth were retreated using chloroform as a solvent. Removal of filling material was performed manually using K files and H files alternately between carrier and dentinal walls. The average time needed to remove the plastic carrier was 7 min for group I and approximately 6 1/2 min for group II. No deformation of the plastic carrier was observed after removal from the canal. Removal of plastic carriers and measurement of the proper working length were easily performed using manual endodontic instruments. Chloroform greatly enhanced this procedure.

Intraperitoneal infection with Salmonella abortusovis is partially controlled by a gene closely linked with the Ity gene.

The aim of the present study was to determine whether the Ity gene, which controls the resistance to S. typhimurium infection in mice, also governs the resistance to S. abortusovis, a serotype specific for goat and sheep. During either i.v. or i.p. infection, BALB/c mice (Itys) were not able to control the growth of S. abortusovis and eventually died from infection. In contrast CBA (Ityr) or (C.CB)F1 (Ityr/s) mice were able to control the growth of these bacteria. Using congenic C.D2 Ityr mice, we found that the gene controlling resistance to S. abortusovis was tightly linked to the Ity gene on chromosome 1. Furthermore, in the spleen and the liver of backcross BALB/c x (CBA x BALB/c) mice, the S. abortusovis resistance phenotype cosegregated with the two alleles of the Len-1 gene, a gene tightly linked to the Ity gene. By contrast, in these backcross mice, the level of infection of the peritoneal cavity, the site of inoculation, did not correlated with the Len-1 phenotype of the animal. These results provide evidence that after i.p. inoculation the control of S. abortusovis growth in the spleen and the liver is controlled by the Ity gene, but also suggest that additional gene(s) regulate the number of bacteria at the site of inoculation.

Syp-3, a third polymorphic locus for mouse seminal vesicle proteins.

The B10.AKM/Sn congenic strain displays a particular phenotype of mouse seminal vesicle proteins representing the third polymorphic locus of this system. The Svp-3 symbol was assigned to this locus with two codominant alleles, Svp-3a found in the B10.AKM/Sn strain and Svp-3b expressed by all the other strains so far tested. The Svp-3 locus appears tightly linked to Svp-1 on chromosome 2.