(BQ) Part 1 book Orthodontics - Prep manual for undergraduates has contents: Introduction to orthodontics, concepts of growth and development, theories of growth, growth of facial structures, child psychology, development of occlusion and normal occlusion, stomatognathics in orthodontics,... and other contents.
Orthodontics Prep Manual for Undergraduates THIRD EDITION Sridhar Premkumar, BDS MDS Professor, Department of Orthodontics and Dentofacial Orthopaedics Head, Department of Paediatric and Preventive Dentistry, Tamil Nadu Government Dental College and Hospital, Chennai, INDIA Table of Contents Cover image Title page Copyright Dedication Preface to the third edition Preface to the first edition Acknowledgements Development of a Concept Introduction to orthodontics Definition and divisions of orthodontics Need for orthodontic treatment and unfavourable sequelae of malocclusion Aims, objectives and/or goals of orthodontics Edward hartley angle Epidemiology of malocclusion Brief epidemiology of malocclusion Ideal requirements of malocclusion indices Various indices used in orthodontics Index of orthodontic treatment need Treatment priority index by grainger Growth and Development Concepts of growth and development Growth and development: Definition and differentiation Nature of skeletal growth/hyperplasia/hypertrophy/extracellular matrix secretion Osteogenesis/methods of bone formation Remodelling Growth site versus growth centre Growth movements: Drift versus displacement Expanding V principle Pattern of growth Variability of growth Safety valve mechanism Differences between primary and secondary cartilages Controlling factors in craniofacial growth Age assessment: Chronological, dental and skeletal age Role of synchondroses in cranial base growth Various methods of measuring growth Craniometry and anthropometry Vital staining Implant radiography Clinical implications of growth and development Nasal septum Meckel’s cartilage Theories of growth Various theories of growth Growth of facial structures Prenatal growth of maxilla Prenatal growth of palate Prenatal growth of mandible Postnatal growth of maxilla Postnatal growth of palate Postnatal growth of mandible Condylar growth Development of tongue Child psychology Need to study child psychology Theories of developmental psychology Correlation of various theories of psychology: Refer table 6.2 Behaviour learning theories Types of child behaviour Motivation of a child Child behaviour management techniques used in orthodontics Behaviour modification techniques useful in orthodontics Development of occlusion and normal occlusion Eruption of teeth Stages of tooth development Chronology of human dentition Development of occlusion from birth till 12 years and adolescence Terminal plane relationship and transition of molar–occlusal relationship from mixed dentition to permanent dentition Self-correcting malocclusions/transitional or transient malocclusions Keys of occlusion Stomatognathics in orthodontics Stomatognathics: Definition and its various components Trajectorial theory of bone formation/julius wolff’s law Trajectories of force/benninghoff’s lines Buccinator mechanism Various functions of stomatognathic system Mastication Infantile swallow/retained infantile swallow Deglutition/adult or mature swallow Speech and malocclusion Development of Problems Classification of malocclusion Malocclusion definition Definition of classification in orthodontics Methods of recording and measuring malocclusion/various methods of classification of malocclusion Angle’s classification of malocclusion Merits and demerits of angle’s classification/validity of angle’s classification Modifications of angle’s classification Simon’s classification Incisor classification/british standard classification of incisor relationship Ackerman–proffit classification Quantitative methods of classification of malocclusion 10 Aetiology of malocclusion Classification of aetiologic factors Prenatal causes of malocclusion Role of genetics in malocclusion Butler’s field theory Postnatal causes of malocclusion General causes of malocclusion Diagnosis 11 Case history and clinical examination in orthodontics Classification of diagnostic aids and various diagnostic methods employed in orthodontics Importance of case history in orthodontic diagnosis Clinical evaluation of orthodontic patient 12 Radiographs and related diagnostic aids Radiographs used in orthodontics Role of intraoral radiographs in orthodontics Panoramic radiography Facial photograph as a diagnostic tool Hand–wrist radiographs Electromyography Digital radiography 13 Model analysis Study models/study casts Classification of model analyses/various methods of model analyses used in orthodontics Bolton’s analysis/bolton’s ratio Ashley howe’s analysis Pont’s index/pont’s analysis Linderhearth’s analysis Kesling’s diagnostic set-up Moyer’s mixed dentition analysis Tanaka–johnston analysis Radiographic method of mixed dentition model analysis Carey’s analysis 14 Cephalometrics Definition of cephalometrics Cephalometric radiography Cephalometric landmarks Reference planes used in cephalometry Classification of cephalometric analyses Steiner’s analysis Y-axis/growth axis Tweed’s analysis/tweed’s diagnostic triangle Wits appraisal/analysis Ricketts analysis Mcnamara’s analysis Role of cephalometry in orthodontic diagnosis and treatment planning Visualized treatment objective Biology, Mechanics and Orthodontic Materials 15 Biology of tooth movement Physiologic tooth movement Structure of periodontal ligament and its response to physiological force Theories of tooth movement Biological tissue reaction to the application of orthodontic force Stages of tooth movement Different types of orthodontic force Orthopaedic force 16 Biomechanics of orthodontic tooth movement Newton’s laws of motion and its relevance to tooth movement Terminologies in biomechanics of tooth movement Types of tooth movement Definition and classification of anchorage Sources of anchorage/anchorage sites Factors affecting anchorage Anchorage loss Various types of anchorage with suitable examples Implant as anchorage units/absolute anchorage/temporary anchorage devices 17 Materials used in orthodontics Classification of materials used in orthodontics Wrought alloys/orthodontic metallic materials Annealing/heat treatment of orthodontic alloys Archwires used in orthodontics Table 17.4 Bonding adhesives ACCESSORY POINTS ➤ The first alloy to be used for orthodontic treatment is gold alloy (type 4) ➤ The only appliance that is still being formed with gold alloy is Crozat appliance ➤ Corrosion resistance of stainless steel is due to passivating effect ➤ Shape memory in nitinol is due to phase transformation from martensite to austenite ➤ Superelasticity in Chinese NiTi is due to phase transformation from austenite to martensite ➤ Nitinol wire cannot be soldered and welded ➤ Type solvent type solder is used for orthodontic purpose ➤ Portion of flame zone used for melting solder is tip of reducing flame ➤ Frozen slab technique increases the setting time of cements ➤ Most important fault of ceramic is its brittleness ➤ Linear polymer of β-d-mannuronic acid is commonly called alginate ➤ Wire which exhibits shape memory is nitinol ➤ Joining of two parts of a metal without using a third metal is called welding ➤ The temperature point at which first solid forms on cooling a molten metal is called liquidus ➤ The temperature point at which last liquid solidifies on cooling a molten metal is called solidus ➤ Brazing materials are not used for soldering in orthodontics because they have a very high melting range between liquidus and solidus temperature ➤ Stabilizing agent in stainless steel is titanium ➤ Steel is an alloy of iron in which the carbon content is less than 1.2% ➤ Currently the etching time for etching gels is approximately 15 s ➤ The depth of enamel penetration or etch pit is approximately 10–20 microns ➤ Soft solders have a melting range of approximately 260°C ➤ Soldering techniques used are free-hand soldering and investment soldering ➤ Martensite SS on heating changes to ferrite and carbide, this decreases hardness and increases toughness This is called tempering ➤ Titanium is added six times that of carbon to reduce sensitization Advanced Learning Sterilization and disinfection in orthodontics Definitions Sterilization is defined as the process by which an article, surface or medium is freed of all microorganisms, either in the vegetative or spore state Disinfection denotes the destruction of all pathogenic microorganisms or organisms capable of giving rise to infection The term antisepsis means prevention of infection, usually by inhibiting the growth of bacteria Modes of transmission of infection ➤ From patient to practitioner ➤ From practitioner to patient ➤ From one patient to another (cross-infection) Route of transmission Inoculation: Accidental self-injury with a contaminated needle, sharp instruments The microorganisms transmitted includes HBV, HCV, HDV, HSV I, HSV II, HIV, Neisseria gonorrhoeae, Treponema pallidum and Clostridium tetani Inhalation: Inhalation of microorganisms aerosolized from a patient’s blood or saliva occurs when using high speed or ultrasonic equipment Examples are varicella zoster virus, cytomegalovirus, mumps virus, rubella virus, Mycobacterium tuberculosis and Candida albicans Protection of operators and patients Barrier techniques Gloves Latex gloves must be worn for all patient procedures, and changed between patients If there is allergy to latex or cornstarch, nylon glove linens are used Gloves must also be removed and replaced before handling materials such as charts, study casts and radiographs Protective clothing Long-sleeved, jewel-neck clinic jackets should be worn in the laboratory and operatory These jackets should be replaced daily or when visibly soiled, and worn only in the office They should not be worn outside work area Masks and protective eyewear Masks and protective eyewear are required during bonding and debonding procedures to protect against aerosols of blood and saliva Face shields or side shields should be added to personal eyeglasses Masks and face shields are required whenever a handpiece is used Patients should be provided eyewear during any procedure with a risk of eye injury from debris or chemical agents Limiting contamination To avoid spatter, use high volume evacuations, proper patient positioning and rubber dams Avoid contact with charts, telephones cabinets during treatment Procedures before sterilization Presoaking of instruments using phenol or glutaraldehyde is recommended This procedure keeps instruments wet, prevents drying of saliva and blood on the instruments and facilitating easy cleaning Presterilization cleaning manually or by ultrasonic instruments Advantages of ultrasonic cleanser over manual cleaning ➤ Increased efficacy ➤ Reduced danger of aerosolization ➤ Reduced incidence of instrument injuries ➤ Increased tarnish removal and cleanliness ➤ Reduction in manual labour Classification of instruments to be sterilized: The classifications of instruments based on the need for sterilization with examples are given in Table 17.5 Table 17.5 Classification of instrument based on the need for sterilization Classification Definition Critical Surgical and other instruments which penetrate soft tissue/bone should be sterilized after each use Semi-critical Instruments that not penetrate soft tissue/bone but contact oral tissues Non-critical Items which not come into contact with body fluids Examples Forceps, scalpels, bone chisels, scaling instruments, surgical burs Mirrors, plastic instruments, burs Light cure tips, glass slab, cement spatula, orthodontic pliers, dappen dish Sterilization of orthodontic materials: Sterilization procedures for various orthodontic materials are enumerated in Table 17.6 Table 17.6 Various orthodontic materials and their methods of sterilization Monitoring sterilization There are three forms of monitoring namely physical monitoring, chemical monitoring and biological monitoring Physical monitoring refers to periodical observation of displays or gauges on the sterilizer during a cycle to ensure the sterilization process Chemical monitoring is of two types: Process indicators which consist of colour changing material (liquid/paper) which changes colour upon exposure to appropriate sterilization cycle and TST strips (TIME, STEAM, TEMPERATURE) which change colour when all parameters have been adequately achieved in the sterilization cycle Biological monitoring involves using indicators that are heat-resistant bacterial spores (Bacillus stearothermophilus, Bacillus subtilis) If the spores are killed, then less resistant microbes are killed more readily and sterility is guaranteed Conclusion Sterilization techniques are of utmost importance in preventing the spread of infectious disease This is of special significance in dentistry because more microorganisms are found in the oral cavity than in any other part of the body With the increasing number of adult patients and diverse lifestyles, the orthodontist is more at risk than ever to exposure to serious pathogens and must take precautions to guard against their transfer Braided or twisted or coaxial wires ➤ Extremely small diameter stainless steel wires can be twisted or braided together to form wires in clinical orthodontics ➤ The separate strands may be as small as 0.178 mm (0.007 inch) ➤ The final intertwined wires may be either round or rectangular in shape ➤ These braided wires are able to sustain large elastic deflections in bending ➤ These wires also apply low forces for a given deflection when compared with the similar sized solid stainless steel wire ➤ Initial orthodontic levelling and alignment archwires require great working range to accommodate the malalignment of bracket slots in the untreated malocclusion Coaxial/braided wires offer a good choice wire for the initial alignment and levelling Newer orthodontic wires/non-metallic wires The following are the newer nonmetallic wires used in orthodontics: Optiflex • A transparent nonmetallic orthodontic archwire with a silicon core, a silicon resin middle layer and a stain-resistant outer layer • The brittle core layer prevents placement of sharp bends, but the composite wire is highly resilient • Optiflex was introduced by Talass MF Kusy RP and colleagues developed an archwire which contains ‘S2 glass fibres’ embedded in a polymeric matrix formed from Bisphenol A-Glycidyl Methacrylate (Bis-GMA) and Tri-Ethylene Glycol Di-Methacrylate (TEGDMA) Benzoin Ethyl Ether is present as ultraviolet photo initiator Kusy RP and colleagues developed a composite ligature wire consisting of ultra-high molecular weight polyethylene fibres in poly (n-butyl methacrylic matrix) Researchers at the University of Hokkaido have developed an archwire with polymethyl methacrylate matrix reinforced by CaOP2O5–SiO2–Al2O3 fibres which are said to be biocompatible Watanabe M, Nakata S, Morishita T introduced a polyethylene tetraphthalate wire for maxillary retainers Apart from all these wires, composite coated metallic wires for aesthetics are also available Comparison of different metallic orthodontic wire alloys The clinical efficacy and performance of the different metallic wire alloys are given in Table 17.7 Table 17.7 Orthodontic wire alloys–comparison Recent advances in orthodontic adhesives The newer adhesives used for bonding are as follows: Ormocers (organically modified ceramics) They contain organic–inorganic copolymers in addition to the inorganic silanated filler particles Ormocers are synthesized by sol–gel process from multifunctional urethane and thioether acrylate alkoxysilanes They are three-dimensionally crosslinked copolymers Advantages: They are more biocompatible as they cure without leaving residual monomer Coefficient of thermal expansion is close to enamel Disadvantage: They are highly viscous leading to poor penetration of adhesives into bracket mesh Cyanoacrylates It has the ability to polymerize as a thin film at room temperature without a catalyst in moist environment Disadvantages: • Polymerization process results in a rather short working time of s and might be considered disadvantageous in direct bonding but is well suited for indirect bonding purposes • Bond strength is significantly lower Chromatic adhesives Photochromatic: Bonding adhesive, which is pink during placement, turns clear on exposure to curing light Thermochromatic: This adhesive is dark blue in colour when dispensed and turns into tooth colour above 32°C The colour reverts to blue colour below 32°C to facilitate complete removal at debonding Adhesive-precoated brackets (APC) To save chairside time, there are brackets with precoated adhesive It also standardizes the amount of adhesive used in each bracket and easier to clean up because of minimal amount of flash Various light sources used for curing composite The different light sources used for curing composite are given in Table 17.8 Table 17.8 Comparison of different light sources used for curing composites Magnets in orthodontics Magnets have been used for many years in dentistry, particularly for retention of dentures and over dentures The magnets used initially were made of aluminium–nickel–cobalt (AlNiCo) Because of their toxic nature, their usage was restricted The development of rare earth magnets has led to the application of magnetic forces in orthodontics due to the biomechanical properties and possible biological effects of the static magnetic fields on orthodontic tooth movement In orthodontics, they have been used both in research and clinical practice The rare earth magnets most often used in orthodontics today are samarium–cobalt and neodymium–iron–boron types because they are small enough to be placed intraorally and produce forces that can move teeth Advantages of magnets (darendeliler, 1993) ➤ They are able to produce measured force continuously over a prolonged period ➤ They can be made to attract or repel, so push or pull type of force can be delivered ➤ They can exert force through the bone and mucosa and there need not be direct contact between them Clinical application of magnets in orthodontics ➤ Magnetic functional appliances and growth guidance ➤ Tooth intrusion ➤ Canine retraction ➤ Arch expansion ➤ Molar distalization ➤ Space control ➤ Deimpaction ➤ Correction of class II bimaxillary protrusion ➤ Orthodontic extrusion of fractured crown–root ➤ Retainer Few clinical examples of use of magnet are given in Fig 17.6 FIG 17.6 (A) Diagrammatic representation of a magnetic appliance, (B) functional magnetic activator device and (C) force system for distal movement of canine ... Copyright © 2 016 , 2 011 , 2008 by RELX India Pvt Ltd All rights reserved ISBN: 97 8-8 1- 3 1 2-4 44 6-3 eISBN: 97 8-8 1- 3 1 2-4 64 7-4 No part of this publication may be reproduced or transmitted in any form or by... Building, 21, Barakhamba Road, New Delhi 11 00 01 Corporate Office: 14 th Floor, Building No 10 B, DLF Cyber City, Phase II, Gurgaon -1 2 2 002, Haryana, India Orthodontics: Prep Manual for Undergraduates, .. .Orthodontics Prep Manual for Undergraduates THIRD EDITION Sridhar Premkumar, BDS MDS Professor, Department of Orthodontics and Dentofacial Orthopaedics Head, Department of Paediatric