Are fissure sealants still relevant as a caries preventive measure?

The groundwork for fissure sealants was completed in 1955 and lead to the introduction in 1971 of the Nuva-Seal Fissure Sealant by L.D Caulk. Since caries predominantly affects the pits and fissures of the teeth of children, these sealants have been shown to be a valuable preventive procedure. FS are cost effective and provide an ideal preventive measure for children who have restricted access to dental services. However the advent of dental lasers, caries detection systems, fluoride varnishes and novel adhesive systems may have displaced FS as a preventive measure of choice. The aim of this investigation was to establish whether FS remain a relevant preventive measure for the anatomically vulnerable fissure system

The use of laser-based technologies in dentistry: Ethical issues and safety considerations

The use of laser-based technologies in general dental practice in South Africa is growing each year both in numbers and in scope of use. It has been shown to be beneficial in treating a wide range of oral and dental conditions as well as being used as a therapeutic tool in tissue management. They have been used in the practice of dentistry for over thirty years and recently there have been numerous advertisements in the dental press regarding the advantages of owning and using lasers and how it can be a good marketing tool for a dental practice. In the United States patients seek out practices utilising laser technology and nearly two thirds of patients surveyed thought that dentists should own a laser. How can practitioners ensure that they are using laser treatment for their patients in a responsible and ethical manner?DHE

Bio-active restorative materials as alternative pit and fissure sealants in pediatric and preventative dentistry: In vitro investigation

BACKGROUND: It has been more than 40 years since the pit and fissure sealants were first used clinically. During this time, pit and fissure sealants have been shown to be effective in reducing the risk of occlusal caries. AIM: The aim of the investigation is to further develop and evaluate a versatile designed chitosan based bio-active materials on for use as bonding free fissure sealant/fissure protectors on permanent dentition and evaluate remineralization/demineralization capacity of the materials through pH cycling, as well as shear bond strength etch and no etch prototype as well as measurement of Vickers hardness of the newly designed materials and compare the property with the commercially available standard. RESULTS: In general there was an increase in bond strength of the enamel treated with the modified Premise containing nanodiamond: chitosan materials compared to the bond strength of the conventionally bonded teeth. It is seen that release of phosphorus into the dematerializing solution (i.e. loss of phosphorus from the samples) showed larger amplitude (from 600.2mg to 101.3 mg) than the uptake of phosphorus by the samples from the re-mineralizing solution (from 125.2 mg to 66.1 mg). Therefore, the treatment with chitosan seems to act more on the demineralization of tooth enamel with little effect on the remineralization process. Regarding the net phosphorus loss (net P loss), it can be seen that net demineralization occurs in all cases. However, the net amount of phosphorous released by the control group samples was significantly higher than those groups treated with chitosan. The net P loss for the control group was 475 mg of P, whereas the groups containing chitosan had a net P loss in the range of 30-182 mg. When a 1mm layer is assessed all the materials including the Premise control indicated a conversion of above 96%, which is the upper limit of the conventional fissure sealant material which makes the newly designed bioactive materials suitable for the application as fissure sealant materials. The important aspect of any newly designed/ developed restorative material is cytotoxicity as Grobler et. al [1] investigated the cytotoxic effect of nanodiamonds and also the effect of the incorporation in a dental material (Premise), who found a higher shear bond strength (p < 5%) after 3 months of Premise treated with nanodiamonds, chitosan, cyclodextrin (CD) and combinations thereof than for the control Premise. The sequence for the Vickers hardness was: CD (32.5) < nano (34.8) < CD Nano (38.8) < Premise (39) < Chitosan Nano (42.2). Nanodiamonds (92%) and the combination of chitosan + nanodiamonds (93%) showed little cytotoxicity. The shrinkage was lower for all the additions than for Premise alone. CONCLUSION: All modified Flowable bio-active materials can be further developed in effective fissure sealant material based on the acceptable in vitro results and cytotoxicity data

Comparison of the degree of powder to liquid ratio variation in capsulated glass ionomer restorative cements

The aim of this study was to compare the liquid/powder content of three capsulated glass ionomer restorative cements. Three glass ionomer restorative cement materials were selected from the Paediatric dentistry clinic. The liquid content followed by the powder content was removed methodically and weighed on a chemical scale. 45 samples sealed material capsules were randomly removed from the box of materials. KMA had the lowest average liquid (0.085g) and powder (0.288g) content with the results of the n15 KMA capsules closely grouped together. A statistical difference (P<0.001) was noted between the mean values of the liquids (CR, PGN, KMA), although the individual values had a wide spread. The powder variation was very small based on the spread. A statistical difference exist (P<0.0001) between the means of the recorded powder weights of CR (0.45g), PGN (0.37g) and KMA (0.29g). The decrease in the volume of the liquid could have various reactive possibilities with the powder. The handling and physical properties will be altered according to the liquid content at the time of titration of the GIC capsule. Manufacturers should ensure that the machines provide sufficient filling of the liquid chamber and ensure that no liquid is lost from the liquid chamber of the capsule, either by evaporation or capsular absorption before the materials expire date. Abbreviations and acronyms: GICs: Glass ionomer cements, Chemfil Rock: CR, ProGlass Nine:\nPGN, Ketac Molar Aplicap: KMA, standard deviation (SD

In vitro analysis of techniques that alter the surface hardness of a glass ionomer restorative material

Glass ionomer cement as restorative materials are advantageous in pediatric restorative dentistry. The main advantages of GIC include fluoride release up to 50 μg/cm and a chemical adhesion to the tooth structur

Volumetric change due to polymerization in dental resins as measured with an electronic mercury dilatometer

Magister Scientiae Dentium - MSc(Dent)Objectives: To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. Background: The volumetric change that occur during the polymerization of dental composite restorations are considered to be one of the most significant contributing factors when considering the failure in composite restorations. Volumetric shrinkage of more than 2% is considered to be enough to result in the occurrence of secondary caries resulting in fracture of restorations and failure in the adhesive layer of a resin restoration. The total volumetric change of dental resins can be attributed to three main factors: Firstly, the polymerization reaction that results in the formation of a polymer chain. Secondly, the increase of the exothermic thermal effects produced by the polymerization reaction and thirdly, light irradiance energy that is transferred to the dental resin. Materials and Methods: A specially designed electronic mercury dilatometer at the UWC Oral and Dental Research Institute was used to determine the volumetric change. The light intensity was set at 500mW/cm2. The mercury dilatometer measured the volumetric change every 0.5 seconds during the 35 second irradiation exposure time. The materials tested were Z250 as the control and four bulk fill flowable composites. The volume of voids within the cured material samples were assessed with a Micro-3D ct reconstruction (General Electric Phoenix). Results: The sequence of total volumetric change from least to most were: Z250 < Filtek bulk fill < Xtra-Base bulk fill < SDR < Venus bulk fill. The speed/rate of shrinkage of the bulk fill flowable composites were faster than that of Z250, while the 2 bulk fill flowables with the highest shrinkage speed (SDR and Venus) also had the highest total volumetric change. Of the different materials tested the volumetric change of Z250 (1.13%) was the lowest and significantly less (p<0.05) than that of SDR (1.56%) and Venus (1.72%). The Kruskal-Wallis multiple comparison test indicated that the material with the highest filler content (Z250) also showed the lowest shrinkage (1.13%) but this effect of the filler content could not be seen in the bulk fill flowable composites. The volume of the voids within the test specimens were determined and were represented as a percentage of the cured volume (49.087mm³). Venus had the largest percentage of voids (1.18%) in the test specimen (specimen volume: 49.087mm³), followed by Z250 with 0,5248%, Xtra base with 0,00015%, SDR with 0,00059% and Filtek bulk fill with 0,00069%. Conclusions: The volumetric changes and rate of shrinkage were higher for all 4 bulk fill flowable composites than for Z250. Furthermore, the speed of shrinkage based on the polymerization reaction differed between the materials. SDR and Venus flowables had the fastest rate and highest volumetric change. The small percentage of voids within the materials seemed not to have affected the volumetric change negatively. Clinical significance: The manufacturers of bulk fill flowable composites advocate filling layers of 4mm. However, because of the high shrinkage values found in this study the use of the standard 2mm layer increments is recommended

An in vitro study of the properties of GICs with bioactive biomaterial modification

Philosophiae Doctor - PhDThe fluoride release and chemical adherence to tooth structure remain the most desirable features of glass ionomer restorative cements (GICs). Although the physical properties for multi-surface restorations are well-defined, even with the introduction of newer GICs not all demands have been met. Yet, increased use of GICs will only be possible if clinicians change their perceptions of the low survival rate of GICs. The lower clinical success rate of GICs is partly due to the marginal integrity and wear over time, which has often been recorded in the literature as restoration failure. The current, well-established restorative options for the primary dentition are Resin Modified Glass Ionomers (RMGICs) and Compomer resins. There is a paradigm shift towards materials that are more biologically favourable. Areas of research for dental materials include antibacterial properties in conjunction with ion release to maintain healthy restored teeth. If a GIC can provide adequate physical properties with the inclusion of the aforementioned features, GICs might become a more viable permanent restorative solution

COVID-19: The invisible risk to oral healthcare workers in dentistry

Oral healthcare workers (OHCW) include any professional who can work in a dental practice setting, for example dentists, dental hygienists, dental therapists, dental assistants and denturists. Dentistry, as a profession, faces an overall elevated risk of exposure to a wide variety of infectious diseases originating from viruses and bacteria. There are numerous pathways of potential exposure to these micro-organisms. Additionally, OHCW carry a very high risk of Covid-19 transmission as a result of face-to-face communication and close proximity during dental procedures with patients, as the oral cavity and the respiratory tract can contain and transmit Covid-19

Lasers in periodontics

Ablation has been described as the expansive vaporisation of tissue. In periodontal procedures the ablation capacity of the laser can be used for excision and incision of pathology. The Erbium doped lasers can be used effectively for soft tissue procedures with or without water. It is essential that the air supply is turned off when soft tissue procedures or any procedure with a flap is performed, to prevent subcutaneous emphysema. Hard tissue lasers are effective in bone ablation provided that the water is present preventing collagen denaturation and necrosis of the targeted tissue.DHE

Cavity preparation using hard tissue lasers in operative dentistry

A laser is a device that delivers coherent, monochromatic and collimated light as a form of energy. Most dental laser devices emit invisible light in the infrared portion of the electromagnetic spectrum. On May 7, 1997, the Food and Drug Administration (FDA) cleared for marketing in the United States the first erbium: yttrium - aluminum -garnet, or Er: YAG, laser for use in preparing cavities in the teeth of living human subjects