Dental Anatomy Overview Week 6 PDF

**[Week 6]** **[Dr Sfera L1- Introduction to Dental Anatomy- overview]** Dental Morphology- Distinct features or traits of the crowns and roots of the teeth, that are present or absent and when present, exhibit variable degrees of expression Dental Anatomy- The study of the development, morpholog...

**[Week 6]** **[Dr Sfera L1- Introduction to Dental Anatomy- overview]** Dental Morphology- Distinct features or traits of the crowns and roots of the teeth, that are present or absent and when present, exhibit variable degrees of expression Dental Anatomy- The study of the development, morphology, function and identity of the human teeth, and their relation to the other teeth in the same and opposing arch **Orientation Terminology Charting terminology**  **Parts of the teeth** A diagram of different types of teeth Description automatically generated **[Dr Sfera L2- Dental Morphology- Terms and definitions]** **Proximal contact area** - The area of proximal height of contour of the mesial or distal surface of a tooth that touches the adjacent tooth **Definitions** - Interproximal space is the triangular space located between the teeth. Base is the crest of the alveolar bone, and the apex is the contact area - Interdental papillae is the gingival tissue occupying the interdental (interproximal) space **Cusp and fossa Terminology** - Cusp: an elevation on the crown making a divisional part of occlusal surface - Fossa: An irregular depression or concavity in the crown of the tooth - Elevation ridge: a linear on the surface of the tooth - Elevation marginal ridge: of enamel an which forms the P of mesial/distal the occlusal margin surface i. F the tooth - The oblique ridge occlusal which ridge: crosses surface a of some molars maxillary in an oblique manner **M**  **Terminology: Tubercle and cingulum** Tubercle-small elevation on the crown made by extra enamel Cingulum- convexity on the cervical 1/3 F an anterior tooth Groove- a linear depression in the form - F a line on the surface of a tooth **Fissured Groove**- A groove which sinks suddenly into the surface of the tooth. A fault in the fusion of the developmental lobes. **Supplemental Groove**- Is supplemental to a developmental groove and is usually not fissured **Pit- a small pinpoint depression where the developmental grooves meet** **Distal Pit and Central pit**  **Angle- where two lines meet** **Line angle- where two surfaces meet** Close-up of teeth Description automatically generated **Palmer's notation** - **The palmer notation consists of a symbol**  **designating in which quadrant the tooth is found and a number indicating the position from the midline** - **Adult teeth are numbered 1 to 8 starting from the midline** - **Primary teeth indicated by a letter A to E beginning with the central incisor and counting distally to the second primary molar in each quadrant** - **Digitalization and the use of computers in communication has led to the adoption of upper case letters to denote the quadrant** - **UR and UL for upper and LL and LR for lower** **Palmer's notation for primary teeth** A close-up of a human mouth Description automatically generated **FDI** A diagram of teeth with numbers and letters Description automatically generated **[Dr Sfera L3- Permanent teeth eruption sequence and timing]** **Tooth formation simplified**  **Eruption and sequencing and timing** - Times are approximate as the ethnic, gender and individual variations play a role - Variations of 6 months either way are not unusual - Teeth has a tendency to erupt late rather than early - More advanced in girls when comparing permanent teeth (but not primary) - Very useful index of maturity- especially when used in conjunction with skeletal age - **Emergence-** tooth showing through the gingiva - **Eruption-** continuous movement from the position of the forming dental bud to occlusal contact - **Chronology of eruption-** mixed and permanent dentition - **Mixed-** from 6 until approx. 12 years of age **Dr Sfera L4- Development of occlusion and Dental Age** **Eruption of Teeth** - **Pre-emergent eruption-** begins soon after the root formation commences - Two processes involved 1. Resorption of bone (and primary tooth) overlying the crown 2. Propulsive mechanism in the direction of the cleared path - Post- emergent eruption- a rapid process from the point of penetrating the gingiva until the occlusal level **Dental Age 6-7** - Mandibular teeth most likely precede maxillary - The first permanent teeth to erupt are most likely Md first molars **Dental Age 8-9** - Eruption of Md and Mx lateral incisors - Continuation of root formation for the first molars and central incisors **Dental Age 9-10** - Md canines close to eruption - Root formation completed for central incisors and first molars - First signs of presence of third molars **Dental Age 10-12** - Eruption of Md and Mx first premolars - Continuation of root formation for second premolars and second permanent molars **Dental Age 12-13** - Eruption of Mx canines, Mx and Md second premolars, Md and Mx second permanent molars - Crowns of third permanent molars close to completion **Dental Age 15-16** - Root formation of ALL permanent molars completed (except the third molars) - Crown completion **[Dr Harini- L1 Preventive products]** **Preventive products** - Toothpaste, brushes, floss, interproximal brushes, mouth rinses, professionally applied topical fluorides - CPP-ACP Casein phosphopeptide-amorphous calcium phosphate - Fissure Sealants **Toothpastes** - No fluoride i. Fluoride is not recommended for children under 18 months ii. Unfluoridated toothpaste optional for babies 6-18 months but runs risk of encouraging sweet flavours iii. In small amounts iv. Contains xylitol as a sweetener (anticariogenic) - Low fluoride (500-550ppm) (children 18 months-6 years) i. Labelling does not reflect Australian recommendations ii. Not all children's TP are the same-always have parent's check Fl content - Standard Fluoride (1000-1500ppm) A collage of toothpaste boxes Description automatically generated A table of informational information Description automatically generated with medium confidence  - High fluoride (5000ppm) i. For adults at high risk for dental caries ii. Available at pharmacy or dental offices only iii. Must be stored out of children reach **Toothbrushes** Manual - Soft, nylon, round ends - Appropriate size and shape Electric - Better than manual - Rotating/oscillating/pulsating better than sonic - Reverse focus occasionally has merit **Visual Tools** - Blue is bad - Pale blue is the worst- tooth is undergoing decalcification **Floss aids** **Super floss** - Good for under bridges or orthodontic wires **Interproximal brushes** - Patients who struggle with floss should be encouraged to try interproximal brushes **Mouthwashes** Main types: - Chlorhexidine- antibacterial properties (gingivitis treatment) 0.12% and 0.2%. Available in gel. Give for at least 2 weeks. If long term, Dilute. - Causes inflammation of gingiva, causes staining. Very long term can cause altered taste - Essential oils- menthol, thymol, methyl salicylate and eucalyptol. Probably doesn't penetrate plaque - Avoid alcohol-containing mouth rinses if soft tissue reacts or patient has risk - Betadine or iodine has very good properties in terms of antibacterial, antifungal and antiviral activity. CANNOT BE PRESCRIBED TO PREGNANT WOMEN - Eucalyptus, menthol, thymol, wintergreen - E.g. Fl- Other/mod risk **CPP-ACP- cannot be used in patients who are lactose intolerant** - Tooth mousse Plus (has 900ppm fluoride) - Milk based product which helps in remineralization and prevents dental caries - The casein phosphopeptide forms nanoclusters with amorphous calcium phosphate which maintains super saturation of saliva - It can also help in the buffering of plaque pH - It should not be used on patients with milk protein allergy - CPP-ACP with fluoride demonstrates a synergistic remineralization potential - It can be delivered in a crème or chewing gum - Blocks the dentinal tubules to reduce sensitivity - Can added to some GICs **Professionally applied Topical Fluoride** - Individuals can identified as being of: i. Low risk ii. moderate risk iii. high risk or very high risk for dental caries - Fluoride varnish is used on patients at moderate, high or very high risk of caries **Topical Fluoride** - Forms-\> gels, foams and varnish - Varnish has superseded the other two - Reasons: 1. Patient compliance 2. The higher ppm of fluoride 3. Its in contact with the teeth longer 4. The ability to place it intraorally in any setting 5. Its effectiveness - Advised for patients, especially children at risk of caries **Fluoride Varnish** - 5% NaF (22.6mg F/ml or 22,600ppm) - Very safe - Can be applied 2X per year - Its viscous - Forms a yellow coating - Should not eat or drink for 30 minutes **Newer forms of fluoride varnish** - Clinpro White varnish with TCP (Tri-Calcium Phosphate) - MI Varnish: F varnish with CPP-ACP **Silver Fluoride- NOT USED IN THE TREATMENT OF CARIES. USED TO ARREST PROGRESSION OF CARIES** - Silver Diamine Fluoride - Dentine Desensitiser - Arrest caries - Silver Fluoride + potassium iodide **Factors that increase caries risk** - Cariogenic diet - High titres of cariogenic bacteria, poor oral hygiene - Poor family oral health - Enamel defects, previous restorations - Irregular dental care (attend for ROP-relief of pain only) - Orthodontic treatment, poor restorations (e.g. overhangs or open margins) - In babies- using a bottle as a pacifier **Low risk** - No new caries for\> 3 years - Encourage them to continue what they are doing i.e. reinforce continued need for good diet, hydration and oral hygiene. Monitor for any changes **Moderate risk** - One or two new carious lesions in past three years or the presence of a factor that increases risk **High risk** - Three or more new lesions over three years - Any caries in child \ a. To remove/modify the smear layer which is 1-5 microns thick and composed of mineralized college debris, hydroxy apatite, dentine proteins, bacterial, saliva b. Also to create microporosity on tooth structure 2. Application of adhesives - Modality of adhesives mechanism i. Enamel bonding system ii. Dentine bonding system **Enamel bonding mechanism** - Acid etching (or conditioning) i. Increases the micro retention by uneven solution of enamel prisms: a. Type 1 core (honeycomb appearance) b. Type 11 periphery (cobblestone-like) c. Type 111 is mixed - Increases the surface tension of enamel by removing surface contamination (e.g. pellicle and smear layer) - The mechanism of bonding is micromechanical - Bonding strength Prismatic\Interprismatic - The bonding strength of mixed form is inconsistent - All of them provides acceptable bonding strength **Enamel Bonding failure** - Don't rub etchant into surface - Don't over etch - Without using rubber dam enamel bonding failures are adhesive +cohesive failures, whereas with rubber dam the failures are cohesive - Eliminate unsupported enamel and increase the bonding surface by beveling the enamel margins except on the occlusal area **White lines** Causes: 1. Unsupported enamel cracked due to shrinkage of the composite 2. A thin section of composite cracked under the occlusal force 3. Overheating composite when polishing composite without water **Dentine bonding mechanism** Dentine conditioner: modify the smear layer. Total etch removes the smear layer  **Primer (Coupling Agent)** - Bifunctional monomer - Hydrophilic end group (OH, COOH, P-(OH)~3~)-Spacer-methacrylate end group - Carboxyl bonds to HA (Ca) - Phosphates bond to collagen (amino, amido, hydroxyl, carboxyl) - Photo initiators/chemical cure - Solvent 1. Ethanol 2. Acetone 3. Water **Application of primer** - The method of application of primer determines whether micro leakage will develop - Deep demineralization can result in incomplete penetration of primer - Excessive air thinning should be avoided to avoid collapsing of collage fibers - Although some micromechanical retention is provided by sealer resin tag, but the primer determines the quality of bond **Different bonding systems** - 4^th^ generation example: Optibond FL- etch and rinse (total etch)+prime+bond 3-bottle - 5^th^ generation: Optibond solo plus- etch and rinse (total etch)+prime-bond 2-bottle - 6^th^ generation: Clearfil SE Bond 2- Self-etching primer (self-etching no rinse) +bond- 2-bottle - 7^th^ generation: scotchbond universal, iBond universal, G-aenial Bond- Etch-Prime-Seal (self-etching no rinse) One bottle without mixing (MDP-based) 1 bottle - 8^th^ generation/universal system: Futurabond DC, Scotch bond universal plus Etch-Prime-Seal (self-etching no rinse) One bottle without mixing multi modal (MDP+silane + nano fillers) 1- bottle MDP - 10-methacryloxydecyl dihydrogen phosphate a phosphoric ester monomer that chemically bonds to metals/metal oxides as well as hydroxyapatite ensuring a reliable adhesion to both enamel and dentin - MDP-based adhesives preserve the collagen within the hybrid layer by simultaneously improving collagens resistance to exogenous enzymes and inhibiting MMP (Matrix metalloproteinases) activity, both of which contribute to the longevity of dentin-resin bonding **Challenging dentine structural variation**  **Breakdown of dentin bonding** - Polymerisation shrinkage - Stress on bonding Full bond strength is achieved (24hr). This explains failure ceramic veneers to sclerotic dentine (wear cases) - C-factor effect - Void or porosity due to poor handling - Different coefficient of thermal expansion - Internal stress from occlusal load - Chemical attack, such as hydrolysis **Effect of Bond area on polymerization shrinkage stresses C-factor** - As the C factor increases so too does the possibility of bond disruption when using a composite resin. This effect is caused by a reduction in unbounded surfaces in which the composite can "flow" to relieve polymerization stress. The technique has been suggested to compensate for preparations with high configuration factors A method to improve longevity of dentine bonding - Application of chlorhexidine 2% after acid etch and before applying the bonding agent inhibits matrix metalloproteinases (MMPs) preventing degradation of collagen fibers and stablising the hybrid layer, thereby enhancing the longevity and durability of the bond - It is typically applied for about 60 seconds and then gently air-dried to remove excess moisture without washing it off - 2% chlorhexidine is compatible with most adhesive systems