Application of Lasers in Orthodontics

Journal of Structural Biology, 2013

Structure and composition of teeth of the saltwater crocodile Crocodylus porosus were characterized by several high-resolution analytical techniques. X-ray diffraction in combination with elemental analysis and infrared spectroscopy showed that the mineral phase of the teeth is a carbonated calcium-deficient nanocrystalline hydroxyapatite in all three tooth-constituting tissues: Dentin, enamel, and cementum. The fluoride content in the three tissues is very low (<0.1 wt.%) and comparable to that in human teeth. The mineral content of dentin, enamel, and cementum as determined by thermogravimetry is 71.3, 80.5, and 66.8 wt.%, respectively. Synchrotron X-ray microtomography showed the internal structure and allowed to visualize the degree of mineralization in dentin, enamel, and cementum. Virtual sections through the tooth and scanning electron micrographs showed that the enamel layer is comparably thin (100-200 lm). The crystallites in the enamel are oriented perpendicularly to the tooth surface. At the dentin-enamel-junction, the packing density of crystallites decreases, and the crystallites do not display an ordered structure as in the enamel. The microhardness was 0.60 ± 0.05 GPa for dentin, 3.15 ± 0.15 GPa for enamel, 0.26 ± 0.08 GPa for cementum close to the crown, and 0.31 ± 0.04 GPa for cementum close to the root margin. This can be explained with the different degree of mineralization of the different tissue types and is comparable with human teeth.

Methods in molecular biology (Clifton, N.J.), 2017

To study tooth cycling in polyphyodont animals, we chose to work on alligators. Alligators have teeth in three phases of development at each tooth location. This assembly of three teeth is called a tooth family unit. As part of the study, in order to study tooth cycling in alligators, we wanted to know the configuration of the tooth family unit in every tooth position. From the surface of the mouth, this is difficult to assess. Therefore, we decided to use MicroCT which can image X-ray dense materials providing a three-dimensional view. MicroCT provided us with valuable information for this study. The method described below can be applied to study tooth cycling in other vertebrate species.

Dental Clinics of North America, 2004

Public Health in Developing Countries - Challenges and Opportunities, 2019

Laser have various periodontal applications including calculus removal (erbium yttrium scandium gallium garnet and erbium yttrium aluminum garnet lasers), decontamination of root and implant surfaces and bio stimulation, incision and ablation, osseous surgery, excision of the soft tissue, and bacterial reduction. This chapter analyzes the most important occasions in which lasers are used in implant and periodontal field practices. There is a strong evidence that laser is used for surgical and nonsurgical periodontal therapies including root bio modification, bacterial decline and decontamination of infected implant surface (in peri-implantitis), and removal of the pocket epithelium. This chapter also highlights the most common disadvantages as well as the advantages of using lasers in periodontal therapy. Waterlase® and Periowave™ systems are recent devices that have further revolutionized the laser technology for its favorable clinical applications; however, the procedural cost with the laser device constitutes an obstacle for its routine application.

2005

he dentin-enamel junction (DEJ), which is the interfacial region between the dentin and outer enamel coating in teeth, is known for its unique biomechanical properties that provide a crack-arrest barrier for fl aws formed in the brittle enamel 1. In this work, we reexamine how cracks propagate in the proximity of the DEJ, and specifi cally quantify, using interfacial fracture mechanics, the fracture toughness of the DEJ region. Careful observation of crack penetration through the interface and the new estimate of the DEJ toughness (~5 to 10 times higher than enamel but ~75% lower than dentin) shed new light on the mechanism of crack arrest. We conclude that the critical role of this region, in preventing cracks formed in enamel from traversing the interface and causing catastrophic tooth fractures, is not associated with the crack-arrest capabilities of the interface itself; rather, cracks tend to penetrate the (optical) DEJ and arrest when they enter the tougher mantle dentin adjacent to the interface due to the development of crack-tip shielding from uncracked-ligament bridging. The DEJ in teeth represents the zone between two distinct calcifi ed tissues with very different biomechanical properties: enamel and dentin 1. Enamel is the hard and brittle outer portion of the tooth that envelops the softer dentin; it comprises defective carbonaterich apatite crystals arranged in enamel rods (4-5 µm in diameter) or prisms that lie nearly perpendicular to the DEJ 2,3. Its fracture toughness (K c) typically ranges from ~0.7 MPa m 1/2 in the direction parallel to the enamel rods to ~1.3 MPa m 1/2 in the perpendicular direction 4,5. Dentin, conversely, is a biological composite that is tougher than enamel and similar at the nanostructural level to bone. It has a unique architecture consisting of dentinal tubules, ~1 µm in diameter, surrounded by peritubular dentin, consisting of ~0.5-1-µm-thick cylinders of randomly oriented apatite crystallites. These tubular units are embedded in a collagen matrix-apatite reinforced composite. As the tubules are the formative tracks of the odontoblastic cells that move inward and reside on the pulp chamber surface, there are substantial variations in morphology and structure of the dentin from the DEJ to the pulp chamber 6. Dentin has a K c toughness that varies between 1.0 and 2.0 MPa m 1/2 in directions perpendicular and parallel to the tubules 7,8. The toughness of dentin adjacent to the DEJ, so-called mantle dentin, is supposedly higher due

IP Indian Journal of Orthodontics and Dentofacial Research, 2021

In today’s time laser has been used widely in various fields of dentistry, out of all one is in the field of orthodontics and proved to be as useful equipment. Specific lasers such as soft tissue lasers can be used in the treatment of exposure of the tooth surgically with its prime advantage of very less bleeding as well as little bit of swelling it is also helpful in reducing the potential of post reducing pain. Along with all this the other applications of lasers in the field of orthodontics are, they are helpful in etching the superior most surface of the tooth i.e. enamel as well as helpful in bonding of the bracket to the enamel and vice versa i.e. debonding of the bracket from the superior most surface of the tooth i.e. enamel. Lasers are also helpful in tooth movement along with reducing the pain threshold.

Lasers in Medical Science, 2013

Altering the structure of the enamel surface around the orthodontic bracket by reducing its content of carbonate and phosphate resulting from application of CO 2 laser may represent a more effective strategy in preventing caries in this region. This study aimed at determining whether irradiation with a CO 2 laser combined with fluoride-releasing bonding material could reduce enamel demineralization around orthodontic brackets subjected to cariogenic challenge. Ninety bovine enamel slabs were divided into five groups (n018): non-inoculated brain-heart infusion broth group, non-fluoride-releasing composite resin (NFRCRcontrol group), resin-modified glass ionomer cement (RMGIC), CO 2 laser + Transbond (L+NFRCR) and CO 2 laser + Fuji (L+RMGIC). Slabs were submitted to a 5-day microbiological caries model. The Streptococcus mutans biofilm formed on the slabs was biochemically and microbiologically analysed, and the enamel Knoop hardness number (KHN) around the brackets was determined. The data were analysed by ANOVA and Tukey tests (α 00.05). Biochemical and microbiological analyses of the biofilm revealed no statistically significant differences among the groups. Lased groups presented the highest KHN means, which statistically differed from NFRCR; however, no difference was found between these lased groups. RMGIC did not differ from NFRCR which presented the lowest KHN mean. The CO 2 laser (λ010.6 μm; 10.0 J/cm 2 per pulse) use with or without F-bonding materials was effective in inhibiting demineralization around orthodontic brackets. However, no additional effect was found when the enamel was treated with the combination of CO 2 laser and an F-releasing material.

Operative Dentistry, 2008

This study determined the compositional changes and microhardness of the cavity floor prepared by Er,Cr:YSGG and Er:YAG lasers and compared the results with the conventional method of bur preparation. Fifteen non-carious human molars were used in this study. On the buccal and lingual surfaces of each tooth, two cavities (mesio-distal 3 mm, insizo-gingival 3 mm, depth 2 mm) were prepared with two different laser devices (Er,Cr:YSGG laser; Waterlase MD and Er:YAG laser; KaVo Key Laser 3) and a highspeed turbine. The teeth were embedded into polyester resin and cross-sectioned. The microhardness measurements from the floor of each half cavity were recorded with the Vickers surface hardness tester. The remaining halves of the cavities were subjected to SEM-EDS atomic analysis. The results were statistically evaluated by one-way ANOVA and Kruskal Wallis tests (p=0.05). No significant differences were observed among the microhardness values, quantities of Ca (Ca weight %), P (P weight %) and Ca/P ratio of the lased and conventionally prepared cavities (p>0.05). The cavity preparation techniques and differences in laser devices did not significantly alter the composition and microhardness of dentin tissue. Both laser devices used in this study were observed to lead