Final corrected 16-17 Operative (2)

bases/liners/cementsGlass ionomer cements generally contain fluoro-alumino-silica powder.The fluoro-alumino-silica is the portion responsible for one of the majoradvantages of glass ionomer.• Both statements are true• Both statements are false• The first statement is true, the second is false• The first statement is false, the second is true 25 copyright © 2016-2017 Dental DecksOPERATIVE

• Both statements are trueGlass ionomer cements are mixed powder-liquid component systems. The powder is a fluoro-alumino-silicate glassthat reacts with a liquid, which is polyacrylic acid, to form a cement of glass particles surrounded by a matrix offluoride elements.Cements can be used as luting agents: • Zinc phosphate cement: one of the oldest and most widely used cements, zinc phosphate cement, is the standard against which new cements are measured. Advantages: long record of clinical acceptability, high compressive strength, acceptably thin film thickness. Disadvantages: low initial pH, which may lead to postcementation sensitivity, lack of an ability to bond chemically to tooth structure, and lack of an anticariogenic effect. Important: Zinc phosphate cement is mixed using the \"frozen slab\" technique, which greatly extends the working time (by as much as 300%). Note: The pH of newly mixed zinc phosphate cement is under 2 (two layers of varnish must be applied to protect the pulp) but rises to 5.9 within 24 hours and is nearly neutral at 48 hours.The film thickness of zinc phosphate is about 25 mm. • Zinc polycarboxylate cement: also known as zinc polyacrylate cement, was one of the first chemically adhesive dental materials. The adhesive bond is primarily to enamel, although a weaker bond to dentin also forms. This is due to the fact that bonding appears to be the result of a chelation reaction between the carboxyl groups of the cement and calcium in the tooth structure; hence, the more highly mineralized the tooth structure, the stronger the bond. Advantages: kind to the pulp, chemically bonds to tooth structure. Disadvantages: short working time, requires separate tooth conditioning step prior to cementation. Note: It is more viscous when mixed and has a shorter working time than does zinc phosphate cement. • Glass ionomer cement: Advantages: chemical bond to enamel and dentin, anticariogenic effect (releases fluoride), coefficient of thermal expansion similar to that of tooth structure, high compressive strength, low solubility. Disadvantages low initial pH which may lead to postcementation sensitivity, sensitivity to both moisture contamination and desiccation. Note: Its mechanical properties are superior to zinc phosphate and polycarboxylate cements. • Resin-modified glass ionomer luting agents: have properties similar to glass ionomer cements, but have higher strength and lower solubility. Note: They should not be used with all-ceramic restorations dues to reports of ceramic fracture, most likely the result of expansion from water absorption. • Resin luting agents: are unfilled resins that bond to dentin, which is achieved with organophosphates, (2-hydroxyethyl methacrylate [HEMA]), or 4-methacryloyloxyethyl trimellitate anhydride (4-META). Advantages: high compressive strength, low solubility. Disadvantages: irritating effects on the pulp, high film thickness (> 25 mm). Note: As a general rule, resin cements are the best choice for luting ceramic restorations.

bases/liners/cementsZOE cements make good temporary sedative restorations because their pH isvery basic.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 26 copyright © 2016-2017 Dental DecksOPERATIVE

• The statement is correct, but the reason is not*** ZOE cements make good temporary sedative restorations because the pH is neutraland the eugenol has a palliative effect.ZOE-eugenol cement is a soft, sedative-type cement. It is used as a sedative ortemporary filling material, as an insulative base, and in interim caries treatment. Thepowder is zinc oxide and the liquid is eugenol. Eugenol has a palliative effect on thedental pulp, and this is one of the main advantages of using this type of cement.A conventional mixture of zinc oxide and eugenol is relatively weak. In recent years,\"reinforced\" or \"improved\" ZOE-eugenol cements have been introduced (called reinforcedZOE or ZOE-EBA). In reinforced ZOE (Type III ZOE), the powder is composed ofzinc oxide and finely divided polymer particles (polymethyl methacrylate) in the amountof 20% to 40% by weight. In addition, the zinc oxide powder is surface treated by analiphatic monocarboxylic acid, such as propionic acid. Note: This combination ofsurface treatment and polymer reinforcement results in a material that has good strengthand toughness which markedly improves abrasion resistance. Reinforced ZOE is fine forbasing large and complex cavities. This material is able to withstand the pressure ofamalgam condensation and it has minimal effect on the pulp.Contraindications to the use of ZOE include: 1. On dentin or enamel prior to bonding: compromises bonding. 2. As a base or liner for composite resins: eugenol interferes with polymerization. 3. Patients who are allergic to eugenol (or oil of cloves): this is somewhat common. 4. Direct pulp capping: eugenol is a pulpal irritant when in direct pulpal contact.Remember: ZOE is soluble in oral fluids and is difficult to remove from cavitypreparations.

bases/liners/cementsIRM (Intermediate Restorative Material) will interfere with subsequentplacement of a resin filling. This is because IRM is a form of zinc oxide-eugenol.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 27 copyright © 2016-2017 Dental DecksOPERATIVE

• Both the statement and the reason are correct and relatedZinc oxide-eugenol (ZOE) cement is a low-strength base used as a temporary cement fill-ing in the event that the patient will return at a later date for a semipermanent restoration.The powder is mainly zinc oxide and the liquid is eugenol with olive oil as a plasticizer.ZOE is not very durable, and it wears away after just a few weeks, but it works to relievepain, calm the nerve, and protect the tooth. Note: During the Vietnam War, the US Armyinvented a more durable form of ZOE called Intermediate Restorative Material (IRM),which is fortified with plastic powder.Uses: • As an intermediate restorative material for both Class I and II restorations. • As a base under non-resin restorations • Restoration of deciduous teeth (when permanent teeth are 2 years or less from erup- tion) • Restorative emergenciesAdvantages: • High strength comparable to zinc phosphate • Excellent abrasion resistance • Good sealing properties • Low solubilityImportant: Because of its ZOE composition, IRM will interfere with subsequent place-ment of a resin filling.

bases/liners/cementsZinc phosphate cement can cause irreversible pulpal damage because it shrinksslightly on setting.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 28 copyright © 2016-2017 Dental DecksOPERATIVE

• Both the statement and the reason are correct but not relatedImportant: The initial mixture of this cement is very acidic (pH of 3.5) and can causeirreversible pulpal damage if a cavity varnish (2 coats) is not placed on the tooth priorto cementation of the crown.Note: Zinc phosphate cements shrink more when they are in contact with air; thus, thecement should not be allowed to dry out.Zinc phosphate cement is the oldest of the luting cements and thus is the one that has thelongest “track record” and serves as the standard to which newer systems can becompared. It is a powder-liquid system; the powder is mostly zinc oxide (also consists ofmagnesium oxide in the approximate ratio of 9 to 1), and the liquid is orthophosphoricacid. The primary use of zinc phosphate cement is as a luting agent for the cementationof cast restorations. It can also be used as a base material when a high compressivestrength is needed.It has superior strength compared to other cements, and its retention depends onmechanical interlocking (as opposed to glass ionomer and polycarboxylate cementswhich adhere to tooth structure by virtue of the polyacrylic acid in the liquid). 1. Zinc phosphate cement liquid that has lost some of its water content will Notes cause the setting time of the mix to be prolonged. 2. Mixing zinc phosphate cement very rapidly will decrease the final compressive strength of the cement.

bases/liners/cementsZinc phosphate cements should be mixed on a cool glass slab, adding a smallamount of powder to the liquid every 20 seconds. This is done to gain which ofthe following advantages.Select all that apply.• Stronger final set• Lower solubility• Greater viscosity 29 copyright © 2016-2017 Dental DecksOPERATIVE

• Stronger final set • Lower solubilityMixing procedure for zinc phosphate cements: • A cool mixing slab should be used ** Caution: The temperature of the slab should not be below the dew point of the room. • Mixing should be started with the addition of a small amount of powder to the liquid. This procedure, along with the cool slab, increases the working time. • Small increments of powder are added approximately every 20 seconds with vigorous mixing until a creamy consistency is achieved. This will promote a high powder-liquid ratio and a superior cementation medium by providing the following: - a lower viscosity of the mix - a stronger final set - a lower solubility of the set cement*** Important point: The advantages of using the cool slab method are a substantialincrease in the working time of the mix on the slab and a shorter setting time of the mixafter placement in the mouth.

bases/liners/cementsA high caries risk patient with multiple anterior class five lesions presents to youroffice. All of the following would be reasons to choose a glass ionomer overcomposite EXCEPT one. Which one is the EXCEPTION?• Fluoride-releasing capability• Chemical adherence to tooth structure• Superior finishing potential• Acceptable esthetic result 30 copyright © 2016-2017 Dental DecksOPERATIVE

• Superior finishing potential*** Composites have superior finishing potential when compared to glass ionomers but do notprovide the same benefits in the high caries risk patients.Both self-cured and light-cured versions of glass ionomers are available. Light-cured glassionomers are preferred because of both the extended working time and their improvedphysical properties. Because of their limited strength and wear resistance, glass ionomers areindicated generally for the restoration of low stress areas where caries activity potential is ofsignificant concern.Compared to composites, glass ionomers: • Have a lower compressive strength, tensile strength, and hardness • Are generally very technique-sensitive because of their high solubility when first mixedNote: With the newer hybrid or light-cured resin-modified glass ionomers, the aboveproperties have been improved.Glass ionomers are generally considered the nearly ideal base/liner material because of thefollowing properties: • Adhesive bond to tooth structure • Snap set in the light-cured form (for example, Vitrebond) • Anticariogenic: due to fluoride release • Bond to composite: makes for excellent liners for Class V root caries restorations. *** Sometimes called the “sandwich technique.” This technique achieves all the benefits of the glass ionomer cements plus the high polishability, surface hardness, and strong bond to enamel of the composite resin.

bases/liners/cementsWhich of the following materials could be used to cement a bridge and fill acervical lesion?• Glass ionomer• Zinc oxide-eugenol• Zinc polycarboxylate• Zinc phosphate 31 copyright © 2016-2017 Dental DecksOPERATIVE

• Glass ionomer*** Only glass ionomer is used as a cement (luting agent) and a permanent restorative material. Glassionomer cements are often used for root surface carious lesions because of the potential advantage offluoride release in helping to control the spread of caries.After the setting, expansion due to water uptake has been observed for some of the newer resin-modified glass ionomer cements (Fuji Duet, Vitremer, and Advance) compared to a regular resin(bis-GMA or urethane acrylate) cement such as PANAVIA 21, which is a self-cure resin cement,conventional glass ionomer luting cements, and the old standby zinc phosphate cement. Traditional glassionomer, phosphate, and resin cements all undergo contraction during setting. The bis-GMA or urethaneacrylate resin cements all undergo polymerization shrinkage during setting. However, the presence ofglass filler in some resin cement materials reduces the shrinkage and can impart radiopacity. Many of theresin cements are now supplied in the form of dual-cure systems (photo-initiated as well as tertiaryamine-peroxide reaction). Such materials include Adherence, Choice, DUO-LINK, Enforce, Lute-It,Nexus, Opal, RESINOMER, Scotchbond Resin Cement, and Variolink.Remember: It is important to note that the main function of a luting cement is to provide a non-permeable seal at the margins around the restoration. The marginal cement-filled gaps around inlays,crowns and bridge abutments can range from 25 to 150µm. Research has shown that the wider thecement gap at the margin, the greater the cement loss (ditching). A rough cement surface is an ideal sitefor plaque accumulation. In such a situation, slow release of fluoride can be a very distinct advantage.Important: In general, glass ionomer cements tend to have the least erosion, and polycarboxylatecements the most. However, solubility, erosion, and strength are significantly affected by the powder/liquid ratio used.Note: Zinc oxide-eugenol (ZOE), reinforced ZOE, ZOE-EBA, silicate, and zinc silicophosphate cementsare no longer routinely used to permanently cement restorations. Zinc phosphate cement has beenextensively replaced by polycarboxylate or glass ionomer cements. These cements are based on ion cross-linked polyacrylic acid matrices that have the potential to react chemically with residual powder particlesand the surface of tooth structure.

bases/liners/cementsAll of the following are advantages for using a zinc polycarboxylate cement overa traditional zinc phosphate cement EXCEPT one. Which one is theEXCEPTION?• Higher Tensile strength• Chemical Bonding to Tooth Structure• Thin Film thickness• Low pulpal irritation 32 copyright © 2016-2017 Dental DecksOPERATIVE

• Thin Film thicknessZinc polycarboxylate cement was the first system developed with a potential foradhesion to tooth structure via chelation. The polycarboxylate cements are powder/liquidsystems. The liquid is an aqueous solution of polyacrylic acid and copolymers. Thepowder is zinc oxide and magnesium oxide.Zinc polycarboxylate cements have a compressive strength slightly lower than that ofzinc phosphate, while the tensile strength is higher. Its final strength depends on thepowder/liquid ratio, with more powder giving greater strength. The strength of the setmaterial is sufficient for amalgam condensation, and its effect on the pulp is mild enoughto eliminate the need for sublining. Thermal conductivity is low and, thus, the materialgives good protection against thermal stimuli applied to metallic restorations.An advantage of zinc polycarboxylate cement is that it can bond to tooth structure. Thisis attributed to the ability of the carboxylate groups in the polymer molecule to chelateto calcium in the tooth. The most commonly noted disadvantages of polycarboxylatecement is its marked thickness and short working time. Currently marketed brandsinclude Durelon (3M ESPE), Liv Carbo (GC America), Hy-Bond® Polycarboxylate(Shofu), and Tylok-Plus (Dentsply/Caulk). The most recent innovation in these cementshas been the development of Durelon Maxicap, an encapsulated version of Durelon. Be-cause it is mixed and expressed from a capsule, the traditional difficulties of shortworking time and excessive thickness are overcome.Remember: When cementing a cast restoration, always apply cement to bothrestoration and the tooth.

bases/liners/cementsWhen using a zinc phosphate cement you place the varnish first. This is becausezinc phosphate cements are not biocompatible.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 33 copyright © 2016-2017 Dental DecksOPERATIVE

• Both the statement and the reason are correct and relatedIt should be emphasized that the use of a base in conjunction with amalgam or gold foil doesnot alleviate the need for a varnish as an aid in sealing the cavity margins against leakage.However, the type of base governs the respective order of application of the varnish and thebase. If a zinc phosphate cement base is to be used, then the cavity varnish should beapplied to the cavity walls prior to placement of the base. On the other hand, if a biocom-patible agent (e.g., a calcium hydroxide, zinc oxide-eugenol, or polycarboxylate cementbase) is employed, then these should be placed against the dentin, and the varnish shouldnot be applied until the base material has hardened. Important: If varnish is addedbefore a biocompatible base, it may prohibit positive qualities such as eugenol’s soothingeffect or polycarboxylate’s chelation and adhesion.Zinc phosphate cements provide good pulpal protection from thermal, electrical, andpressure stimuli, but may damage the pulp as a result of an initial low pH. This, however,can be of benefit as it provides an antibacterial effect that reduces the number of viablemicroorganisms in the cavity floor and, thus, decreases pulpal irritation.Important: Cements used for bases should be mechanically stronger than when used asluting agents and are mixed with the maximum powder content that is possible. A lowpowder-to-liquid ratio produces a low viscosity cement that is needed for luting agents.Note: The varnish will reduce the initial microleakage of an amalgam restoration.

bases/liners/cementsA/An ___________ base is a base that is typically placed over a calciumhydroxide base that has been placed over a pulp exposure.• primary base• secondary base• direct base• indirect base 34 copyright © 2016-2017 Dental DecksOPERATIVE

• secondary baseBases are classified as either primary or secondary: • Primary bases are placed on the dentin in close proximity to the pulp primarily to provide protection from toxic and thermal irritants. Under amalgam and tooth-colored restorations, the primary base is usually calcium hydroxide, whereas, under gold restora- tions, the primary base is usually zinc phosphate cement or zinc polycarboxylate cement. Glass ionomers are commonly used today, as well. • The most common use of a secondary base is the placement of zinc phosphate cement over a calcium hydroxide base which has been placed over a pulpal exposure (direct pulp cap).*** Bases, in essence, serve as a replacement or substitute for the protective dentin that hasbeen destroyed by caries and/or cavity preparation. Important: The thickness of thermalinsulation required for pulpal protection is 1000 to 2000 μm (1.000-2.000 mm).Materials that have been employed as bases (bases are typically 1-2 mm thick): • Zinc phosphate cement: remember to seal dentinal tubules with varnish prior to application • Zinc polycarboxylate cement: provides adhesion • ZOE • Glass ionomer cement:provides fluoride release and adhesion • \"Hard setting\" calcium hydroxide materials: thicker than when used as a liner Remember: All of the above are suitable as a base under amalgam restorations, however, for composites, ZOE cannot be used because the eugenol will inhibit the composite setting reaction.Important: (1) pulpal sensitivity is caused primarily by fluid flow in dentinal tubules; (2) fluidflow is detected by mechanoreceptors on the edge of the pulp; (3) the reduction in tooth sensitivi-ty with decreased fluid flow in tubules is related to the fourth power of the tubule radius.

bases/liners/cementsSolution liners should not be placed under composite restorations because com-posites do not require the pulpal protection.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 35 copyright © 2016-2017 Dental DecksOPERATIVE

• The statement is correct, but the reason is not*** Solution liners should not be placed under composite restorations because they will inhibit thepolymerization of the resin. Suspension liners should be used for pulpal protection in this case.Cavity liners are materials that are placed as thin coatings over exposed dentin. Their main purpose is toprotect the pulp by creating a barrier between the dentin and pulpally irritating agents (i.e., acids frometchants or cements, restorative materials, etc.) by sealing the dentinal tubules.Cavity liners are usually classified into two main groups: 1. Solution Liner (Varnish): thin film; typical thickness range is 2 to 5 μm (0.002-0.005 mm) 2. Suspension Liner: relatively thin film; typical thickness range is 20 to 25 μm (0.020-0.025 mm)1. Solution liner: thin layer to seal off tubules - Varnish: • Organic solvent based; water insoluble • 1 to 2 μm film; used to line cavity up over cavosurface margins • Sets by physical reaction (drying) — just like finger nail polish Commercial examples: COPALITE, Hydroxyline, Chembar, and Tubilitec2. Suspension Liner: • Water solvent based; water soluble • 20 to 25 μm film; used to line only the dentin • Sets by physical reaction (drying) Commercial examples: Pulpdent and Hypo-CalImportant: The above cavity liners are now being substituted with the new dentin bonding systems ordentin sealers (e.g., Gluma or HurriSeal). The dentin bonding systems and dentin sealers are classifiedas solution liners.Notes 1. The average lifetime for the integrity of a varnish film is 1 month. 2. A 50% tubule coverage is produced by one thin coating of varnish. Hence, the reason varnishes should be applied in two thin coats. 3. The chemical composition of COPALITE contains organic resin, chloroform solvent, acetone solvent, and alcohol solvent.

bases/liners/cementsSuspension liners, for example calcium hydroxide, harden intraorally by the:• Chemical reaction of acids and bases• Chemical reaction involving polymerization• Chemical reaction involving chelation• Physical reaction of drying• Physical reaction of a sol-gel transformation 36 copyright © 2016-2017 Dental DecksOPERATIVE

• Physical reaction of dryingDental materials that are designed as pulpal medicaments contain calcium hydroxide or eugenol. Need depends on extent of cavity preparation: • Shallow = 0.5 mm into dentin (Remaining dentin ≥ 2 mm, not necessary) • Moderate = 1.0 mm into dentin (Remaining dentin = 0.5-2 mm, possibly necessary) • Deep < 0.5 mm from pulp (Remaining dentin ≤ 0.5 mm, necessary) Objectives for Pulp Medication: • Eliminate acute inflammation (by soothing the nerves) • Prevent chronic inflammation (stimulate secondary/reparative dentin)Management of Acute Inflammation Eugenol: • Palliative = mitigates, alleviates, or eases pain • Obtundent = reduces violence or pungency by dulling senses Delivery: • Released from cement liner or cement base into dentinal tubules • Short-term effectManagement of Chronic Inflammation: Calcium hydroxide: Delivery: • Released from suspension liner, cement liner, or cement base • Very basic, dissolves in water, and diffuses to pulp • Accelerates formation of reparative or secondary dentin • Method of action unknown Characteristics of Calcium hydroxide, Ca(OH)2, pastes: • Generates very alkaline solutions, pH = 11.0 • Aqueous pastes are viscous and do not wet dry dentin well • Apply without pressure only on concavely excavated dentin • Apply thickness that creates uniform appearance • Set materials are low strength, water soluble, and poorly distinguished on radiographs • Commercial examples: DYCAL (LD Caulk), LIFE (Kerr), and Light-Cured DYCAL

cariesWhen removing caries, which of the following layers of dentin are affected, butnot infected, and therefore do not need to be removed?Select all that apply.• Turbid dentin• Infected dentin• Transparent dentin• Normal dentin• Subtransparent dentin 37 copyright © 2016-2017 Dental DecksOPERATIVE

• Transparent dentin • SubtransparentZones of carious dentin - from innermost to outermost: • Zone 1 (normal dentin): totally normal dentin with no bacteria in the tubules. • Zone 2 (subtransparent dentin): zone of demineralization created by the acid from caries. Damage to the odontoblastic process is evident, however, no bacteria are found in this zone. Capable of remineralization. • Zone 3 (transparent dentin): softer than normal dentin, shows further demineraliza- tion. No bacteria are present. Capable of remineralization provided the pulp remains vital. • Zone 4 (turbid dentin): is the zone of bacterial invasion, tubules are filled with bacteria. Zone is not capable of remineralization and must be removed prior to restoration. • Zone 5 (infected dentin): the outermost zone, consists of decomposed dentin that is filled with bacteria. Must be totally removed prior to restoration.Four zones of an incipient lesion in enamel: 1.Translucent zone: the deepest zone, represents the advancing front of the enamel lesion. 2. The dark zone: does not transmit polarized light. Areas of demineralization and remineralization. 3. The body of the lesion: the largest portion of the incipient lesion. Area of demineral- ization. 4. The surface zone: relatively unaffected by the caries attack.

cariesThe rate of senile caries is increasing, in part, because of the increase in gingivalrecession.• Both the statement and the reason are correct and related• Both the statement and the reason are correct but not related• The statement is correct, but the reason is not• The statement is not correct, but the reason is correct• Neither the statement nor the reason is correct 38 copyright © 2016-2017 Dental DecksOPERATIVE

• Both the statement and the reason are correct and relatedThe rising incidence of root surface caries (sometimes referred to as senile caries) can beattributed to the aging of populations and the fact that most adults are retaining more teeth.In this population, there is increased gingival recession with exposure of root surfaces,leading to the development of root surface caries. Root surface caries usually appears asa well-defined discolored area adjacent to the gingival margin, typically near the CEJ. Itis found to be softer than the adjacent cementum or dentin. Root surface caries generallyspread more on the surface laterally around the CEJ rather than in depth. In older patients,rampant caries can be caused by poor oral hygiene, decreased salivary flow, and side ef-fects of medications. On a dental radiograph, root surface caries appears as a cupped-out or crater-shaped radiolucency just below the CEJ. Early lesions may be difficult todetect on a dental radiograph.Remember: Glass ionomer is a desirable restorative material for root surface carieswhere esthetics is not a major factor.Notes 1. Residual caries is caries that remain in a completed cavity preparation, whether by dentist intention or by accident. 2. Secondary (recurrent) caries is decay appearing at the margins of a restoration and under it. 3. The etiology of root surface caries is currently believed to be the same as for coronal caries — S. mutans, S. sanguis, A. viscosus, A. naeslundii, Lactobacillus, and Veillonella.

cariesChronic caries is characterized by which of the following.Select all that apply.• Pain is common• Slowly progressing or arrested• Common in adults• Entrance to the lesion is small• Lesion is deep and narrow 39 copyright © 2016-2017 Dental DecksOPERATIVE

• Slowly progressing or arrested • Common in adultsChronic caries is sometimes referred to as slow or arrested caries and is also characterized by thefollowing: • The lesion is shallow (small lesion) • The entrance to the lesion is wide • Dark pigmentation with leathery consistency *** Chronic caries should be completely removed when found in enamel and close to the DEJ. *** With chronic caries, pain is uncommonAcute caries, which is sometimes referred to as rampant caries, is characterized by: • The entrance to the lesion is small • The lesion is deep and narrow (large lesion) • Pain may be a feature • Little or no staining • Often multiple, soft-to-the-touch lesions • Most frequently found in children • Rapidly progressingNote: Changes of the pulp and dentin depend on the rate of the carious progression. The responseof the pulp to carious attack or the trauma of operative procedures depends on the blood supply ofthe pulp and its cellular activity.Defense mechanisms of the pulp (to protect it from irritation): • Sclerotic dentin (peritubular dentin formation): initial defense. When it occurs due to the aging process, it is called physiologic sclerotic dentin. When it occurs due to irritants, it is known as reactive sclerotic dentin. • Reparative dentin (irritation dentin formation): second line of defense • Its vascularity (inflammation)

caries_________ is degraded by Streptococcus mutans into ________ and ________,thereby causing caries initiation and progression.• Sucrose, glucans, lactic acid• Glucose, glucans, lactic acid• Sucrose, glucose, acetic acid• Glucose, sucrose, acetic acid 40 copyright © 2016-2017 Dental DecksOPERATIVE

• Sucrose, glucans, lactic acid*** Sucrose is degraded by Streptococcus mutans into glucans and lactic acid, therebycausing caries initiation and progression.Pit and fissure caries has the highest prevalence of all dental caries. Smooth surface areas,especially the proximal enamel surfaces immediately gingival to the contact area are thesecond most susceptible areas to caries. Streptococci and lactobacilli species are common inthis area. The facial and lingual root surfaces may have plaque-containing filamentousactinomyces species that can cause root surface caries.Fluoride treatments will dramatically reduce smooth surface caries, although they are notas effective in preventing pit and fissure caries. Sealing the pits and fissures just after tootheruption may be the single most important procedure to help protect these areas from cariesdestruction.Dental caries has been an intractable disease despite intense dental research. The metabolicacids produced by streptococcus mutans demineralize the tooth surface and lead to dentalcaries. The enzyme dextransucrase produced by streptococcus mutans is the key factor inthis process. Oral bacterial glucosyltransferases (GTFs) use sucrose as a substrate in the syn-thesis of either water-soluble or insoluble glucans (e.g., dextrans, mutans, and levans).Note: Dextransucrase is an example of a glucosyltransferase (GTF).Important: Predominant bacteria found in dental plaque: • Streptococcus sanguis (found the earliest) • Veillonella, Lactobacilli, and Fusobacterium • Streptococcus mutans, mitis, and salivarius

cariesThe initiation of caries requires four entities; choose the four entities from thefollowing choices.• Host• Bacteria• Carbohydrates• Saliva• Time 41 copyright © 2016-2017 Dental DecksOPERATIVE

• Host • Bacteria • Carbohydrates • TimeDental caries is an infectious microbiological disease that results in the localized dissolution of tooth structure. Forcaries to occur, a susceptible host (a tooth), microflora with cariogenic potential (plaque), and a suitable substrate(dietary carbohydrates) all interact to promote the severity of the disease. Note: A certain period of time is alsorequired for caries to develop.The greatest percentage of tooth loss in the first two decades of life (except from the natural loss of deciduous teeth)is due to untreated dental caries. The rate at which the carious destruction of dentin progresses tends to be slowerin older adults than in young persons due to generalized dentinal sclerosis, which occurs with aging.Protective mechanisms of saliva: • Bacterial clearance: glycoproteins in saliva cause some bacteria to agglutinate and then be removed by swallowing 1.5 L of saliva formed each day. • Direct antibacterial activity: salivary proteins (e.g., lysozyme, lactoperoxidase, lactoferrin, and secretory IgA) discourage or even kill bacteria.. • Buffering capacity: of saliva is major role in caries protection. • Remineralization: calcium, phosphate, potassium, and varying concentrations of fluoride are in saliva and assist with remineralization. Some salivary proteins promote remineralization, these include statherin, cystatins, histatins, and proline-rich proteins.Notes 1. Fluoride and occlusal sealants modify the susceptible host (tooth).Remember: Fluoride provides fluoride ion for remineralization forming fluorapatite, which is more resistant to acid attack than intact hydroxyapatite crystals in enamel. 2. Enamel demineralization occurs at pH 5.5 or below. Remineralization of the damaged tooth structure occurs as the pH rises above 5.5. 3. The prevalence of caries has been declining in children. A decline in adult caries is not as evident. Fluoridation has received the most credit for the decline in the development of caries. 4. Pregnant patients, compared with similar nonpregnant patients, are likely to have the same degree of dental caries but more inflamed gingival tissues. 5. Important: The prevailing opinion is that carbohydrate frequency has a higher correlation with dental caries than carbohydrate amount.

cariesThere is abundant evidence that the initiation of dental caries requires a highproportion of:• Lactobacillus within saliva• Streptococcus mutans within dental plaque• Lactobacillus within dental plaque• Streptococcus mutans within saliva 42 copyright © 2016-2017 Dental DecksOPERATIVE

• Streptococcus mutans within dental plaqueThe first event in the development of caries is the deposit of plaque on the teeth. Dental plaqueis a highly organized gelatinous mass of bacteria that adheres to the tooth surface. Streptococcusmutans produce great amounts of lactic acid (acidogenic), are tolerant of acidic environments(aciduric), are vigorously stimulated by sucrose, and appear to be the primary organismsassociated with dental caries, however, they are not the only organisms required for cariesinitiation. Other mutans streptococci species in humans can do this as well (for example, S.sobrinus).Factors to which the tooth surface is directly exposed, and which contribute to the development of dental caries Factor High RiskAmount of plaque Large amount of plaque on teeth, meaning many bacteria that canType of bacteria produce acids (low pH, demineralization) Large proportion of “cariogenic” types of bacteria, resulting in lower pH and sticky plaque and also prolonged acid productionType of diet High in carbohydrates, in particular sucrose; “sticky” diet leading toFrequency of carbohydrates low pH for a longer timeSaliva secretion High sugar frequency resulting in longer time per day with low pH Reduced salivary flow leading to prolonged sugar clearance time and to a reduced amount of other saliva protective systemsSaliva buffer capacity Low buffer capacity resulting in prolonged time with low pHFluorides Absent: reduced remineralizationNote: Xylitol, which is a natural sugar from birch trees, keeps sucrose molecules from bindingwith mutans streptococci. Streptococcus mutans cannot ferment xylitol. Additionally, xylitol causesthe environment to become more alkaline, inhibiting the bacterium's growth.

cariesStreptococcus mutans are ________ and therefore ________.• acidogenic, cariogenic• aciduric, cariostatic• acidogenic, cariostatic• aciduric, cariogenic 43 copyright © 2016-2017 Dental DecksOPERATIVE

• acidogenic, cariogenic*** Streptococcus mutans are acidogenic and, therefore, cariogenic. This means that thesespecies produce acid and, therefore, cause the initiation and progression of caries.Cariogenic bacteria: • Especially members of the mutans streptococci-group (e.g., Streptococcus mutans and Streptococcus sobrinus) • Lactobacilli casei Note: Most current research suggests that the microbial etiology of root caries is very similar to coronal caries. In the past it was thought that Actinomyces species (viscosus and naeslundii) were most commonly associated with root surface caries.Essential properties of cariogenic bacteria: • Acidogenic (produce acid) and aciduric (being able to tolerate an acid environment) *** Note: Lactic acid is formed in large quantities following the degradation of sucrose by mutans streptococci. • The ability to attach to the tooth surface. Note: Streptococci species have special receptors for adhesion to the surface and also produce a sticky matrix that allows them to cohere to each other. • The ability to form a protective matrix. Note: Oral bacterial glucosyltransferases (GTFs) use sucrose as a substrate in the synthesis of either water-soluble or insoluble glucans (e.g., dextrans, mutans, and levans), which extrude from the bacterium and stick to the tooth. This protects it from being removed from the tooth by saliva, liquids, foods, and masticatory forces.Dental plaque describes the soft white film of organized bacterial colonies (main compo-nent),salivary glycoproteins, and inorganic material that readily forms on the surface of teeth.Note: The strong correlation between the presence of dental plaque and the appearance ofdental caries and periodontal disease has been recognized for many years.

compositesAll of the following describe VLC systems EXCEPT one. Which one is theEXCEPTION?• 410-500 nm wavelengths• <300 mW/Cm3 output• 2.5 maximum cure depth• Camphorquinone initiators 44 copyright © 2016-2017 Dental DecksOPERATIVE

• <300 mW/Cm3 outputLight curing of composite formulations arose during the late 1960s with the adoption of ultraviolet (UV)light-polymerized systems. In just a few years, it became obvious that visible light-cured (VLC)composites had many advantages over UV light-cured composites, and practitioners made the shift.Dentistry has been wed to VLC systems ever since.VLC systems have totally displaced the UV light systems. Also, VLC systems are much more widelyused than the chemically activated ones (self-cured). An advantage of light-curing systems as a wholeis that the dentist has complete control over the working time and is not confined to the built-in curingcycle of the self-cure. This is particularly beneficial when large restorations are placed.Note: To deal with problems of incomplete curing with VLC due to the thickness of restorations and fillerparticles scattering light, manufacturers have developed composite resins that are dual-cured, whichcombines self-curing and VLC. Another polymerization method is staged curing, which is a two-stagedcure. However, VLC composites are still the most popular today.Remember: VLC composites are single-component pastes, and the polymerization process is activatedby an external energy source. The alpha-diketone initiator (generally camphorquinone) absorbsenergy from a visible (474 nm-blue light) light source. The ketone absorbs energy and reacts with anamine (added to the system to enhance the effect of the light-sensitive catalyst) to produce free radicals.Notes 1. For large restorations (those that are wider than the diameter of the light tip), cure each area for the full required time. Do not back off light tip until it lights up entire surface of restoration. 2. VLC involves light energy in the range of 410 to 500 nm with a peak intensity of about 470 nm. 3. The minimum acceptable level for visible curing light outputs is 300 mW/cm2. 4. The tip of the light source should be held within 1 to 2 mm of the surface to cure a light shade of material to a depth of 2.0 to 2.5 mm using a standard exposure time of 40 seconds.

compositesAll of the following statements are true concerning posterior compositerestorations EXCEPT one. Which one is the EXCEPTION?• Posterior composite restorations are frequently indicated in the treatment of occlusal lesions that allow conservative preparations• Posterior composite restorations are contraindicated in a patient with heavy occlusion (bruxism)• Posterior composites are contraindicated in patients with high caries risk• Posterior composite restorations may be indicated for the restoration of Class II cavities in premolar teeth where the appearance is very important, the cavity margins are in the enamel, and the occlusal contacts are on the enamel• Posterior composites are contraindicated for cusp replacements unless a dry operating field is maintained 45 copyright © 2016-2017 Dental DecksOPERATIVE

• Posterior composites are contraindicated for cusp replacements unless a dry operating field is maintainedAlthough the ADA does not endorse composite resins as a substitute for amalgam in posterior teeth,composite restorations can be excellent if strict guidelines are followed for tooth selection and if therestorations are done properly. But remember, composite resin restorations are inferior to amalgam interms of compressive strength and abrasion resistance (occlusal wear). Also, current composite resinshave no capability to provide an anticariogenic effect as do freshly placed glass ionomer or resinmodified glass ionomers, for example.The most serious limitation of the visible light-cured VLC posterior composite restoration is thepolymerization shrinkage, which can cause internal stresses and gap formations at butt-joint interfaces,which are seen at the gingival floor of Class II and V restorations. Important: Stress from polymeriza-tion shrinkage is influenced by restorative technique, modulus of resin elasticity, polymerization rate, andcavity configuration or \"C-factor.\" The C-factor is the ratio between bonded and unbonded surfaces; anincrease in this ratio results in increased polymerization stress. Three-dimensional cavity preparations(Class I) have the highest (most unfavorable) C-factor because only outer unbonded surfaces absorbstress. To minimize the stress from polymerization shrinkage, efforts have been directed towardimproving placement techniques, material and composite formulation, and curing methods.Incremental curing reduces the C-factor and, therefore, reduces the residual stress of the resultingcomposite restoration.Note: The major indication for the use of posterior composites is the demand for esthetics by thedentist and patient. Other criteria are non-involvement of cusps, minimal occlusal contact, no excessivewear, and the isthmus must be no wider than one-third of the intercuspal distance.Remember: Composite is the material of choice if the patient has a documented allergy to mercury.Important: In the past, posterior composite restorations were contraindicated in a patient with a caries-active mouth. New concepts state that you should manage the disease (i.e., dental caries) before or at thesame time as you are treating the consequence of the disease (i.e., by placing restorations). Therefore,the current literature does not see a special problem for these restorations in caries-active patients. Theyhave as bad a prognosis as any other restorative treatment if the disease is not managed simultaneously.Note: However, for the National Boards, it is still a contraindication.

compositesWhich property of filled resins is primarily to blame for the failure of Class IIcomposite restorations?• Low flexural strength• Low compressive strength• Low tensile strength• Low wear resistance 46 copyright © 2016-2017 Dental DecksOPERATIVE

• Low wear resistanceIdeally, composite resins should be used only to restore minimal cavities in posterior teeth.Its use should be restricted to those instances which it will not be subjected to excessiveocclusal forces and when teeth are in occlusion, there is cusp-to-cusp contact and not cuspto restoration.For Class III preparations using resins, the rule of extension for prevention into embra-sures is disregarded for Class III esthetic restorations. This compromise is for esthetic rea-sons, as well as the unnecessary removal of tooth structure, which will often involve theincisal edge. If possible, the outline form should place the gingival margin incisally fromthe crest of the gingiva.When placing the composite resin in a Class III preparation, the wooden wedge is placedto provide some separation of the teeth (for contact), to stabilize the mylar strip, and toavoid creation of excess gingival flash. Important: Restoring the contact area must bedone properly and diligently.Remember: For Class III composite preparations, the retentive grooves are placed alongthe gingivoaxial and incisoaxial line angles (entirely in dentin). These grooves will pro-vide for mechanical lock in the preparation. Small, rounded retentive areas are preferred,as contrasted to sharp angles, since it is difficult to insert viscous composite material intothe sharp angles.Note: Once proper finishing has been completed, a thin layer of unfilled resin can be ap-plied as a glaze (this seals the margins and smoothes the surface). The difficulty in fin-ishing composite resin restorations is due primarily to the softness of the resin matrix andhardness of the filler particles. The most desirable finished surface for composites is ob-tained with aluminum oxide disks.

compositesWhich composite type is 35% to 50% percent filled by volume and has anaverage particle size ranging from 0.04 to 0.1 µm.• Microfills• Hybrids• Microhybrids• Packables• Flowables 47 copyright © 2016-2017 Dental DecksOPERATIVE

• • MicrofillsThe first composite resins that were developed contained large filler particles (10-100 microns in diameter) and becameknown as macrofill materials. In the past 20 years, resin-based composites have been improved by reducing particle size, in-creasing filler quantity, improving adhesion between filler and organic matrix, and using low-molecular-weight monomersto improve handling and polymerization. By experimenting with particle size, shape, and volume, manufacturers have intro-duced resin-based composites with differing physical and handling properties. Microfill, hybrid, microhybrid, packable, andflowable composites now are available to be used for varying clinical situations. • Microfills: are 35% to 50% filled by volume and have an average particle size ranging from 0.04 to 0.1 µm. They have low modulus of elasticity and high polishability; however, they exhibit low fracture toughness and increased marginal breakdown. • Hybrids: are 70% to 77% filled by volume and an average particle size ranging from 1 to 3 µm. They do not main- tain a high polish but do have improved physical properties when compared with microfills. • Microhybrids: are 56% to 66% filled by volume and have an average particle size ranging from 0.4 to 0.8 µm. They have particle sizes small enough to polish to a shine similar to microfills but large enough to be highly filled, thus achieving higher strength. The results are resin-based composites with good physical properties, high polishability, and improved wear resistance. • Packable composites: are 48% to 65% filled by volume and have an average particle size ranging from 0.7 to 20 µm. Their improved handling properties are obtained by adding a higher percentage of irregular or porous filler, fibrous filler, and resin matrix. They are indicated for stress-bearing areas and allow easier establishment of physiological contact points in Class II restorations. Research has shown that the physical properties of packable composites are not superior to conventional hybrids. • Flowable composites: are 44% to 54% filled by volume and have an average particle size ranging from 0.04 to 1 µm. Their decreased viscosity is achieved by reducing the filler volume so they are less rigid, yet they are prone to more polymerization shrinkage and wear than conventional composites. Flowable composites have been said to improve marginal adaptation of posterior composites by acting as an elastic, stress-absorbing layer of subsequently applied resin- based composite increments.Restorative Material ApplicationFlowable resin composite PRRs, Small Class V’s, liner/base under posterior compositeHybrid, microhybrid, nanofilled resin Anterior restorations, posterior restorationsMicrofilled resin composite Esthetic areas, anterior restorationsPackable resin composite Class I & II restorationsPolyacid-modified resin composite Class III and V restorations, cervical erosion/abrasion, Class I & II in pediatric patients, sandwich technique for Class II restorationsGlass ionomer High caries risk, cervical abrasion lesions, Class V where esthetics is a concern, atraumatic restorative txHybrid ionomer Class III and V restorations, cervical erosion or abrasion, Class I in pediatric patients, sandwich technique for Class II, liners/bases/ luting cements, temporary restorations

compositesComposite filler particles function to do all of the following EXCEPT one. Whichone is the EXCEPTION?• Reduce the coefficient of thermal expansion• Decrease the tensile strength and compressive strength• Reduce the polymerization shrinkage• Increase the hardness 48 copyright © 2016-2017 Dental DecksOPERATIVE

• Decrease the tensile strength and compressive strength**** The tensile strength and compressive strength are increased.Fillers are placed in dental composites to reduce shrinkage on curing. Physical properties of compos-ite are improved by fillers, however, composite characteristics change based on filler material, surface,size, load,shape, surface modifiers, optical index, filler load, and size distribution.Composition of composites (filled resins): • Filler particles: the filler particles used are strontium glass, barium glass, quartz, borosilicate glass, ceramic, silica, prepolymerized resin, or the like. The particles are usually combined with 5% to 10% weight of very small-sized (0.04 µm) particles of colloidal silica. Note: One micron (µm) is a critical filler size. Fillers greater than one micron are visible to the human eye. As resin matrix around filler particles wears, the filler becomes prominent and visible so the composite surface looks rough. Fillers less than one micron do not produce a rough-appearing surface with aging. Fillers greater than one micron are referred to as macrofills, and fillers less than one micron are referred to as microfills (midi- and mini are in between macro and micro). A new classification of filler is the nanoparticles. The nanoparticles fill between all other particles to further reduce shrinkage. A mixture of different particle sizes is referred to as a hybrid. • Matrix: difunctional monomers either bis-GMA or urethane dimethacrylate (UEDMA). In some cases, a proportion of a lower-molecular-weight monomer, such as TEGDMA, is introduced to lower the viscosity. • Coupling agent: silane which acts as an adhesive between the inert filler and the organic matrix.*** Recently, ions have been added to the filler to produce desirable physical changes. Lithium andaluminum ions make the glass easier to crush to generate small particles. Barium, zinc, boron, zirco-nium, and yttrium ions produce radiopacity in the filler particle.Notes 1. The normal wear mechanism of the composite resins is best explained by the following events: abrasion of the matrix, followed by exposure of filler particles and subsequent dislodgement of these filler particles. 2. With any of the restorative resins, cavity varnish or zinc oxide-eugenol should not be used as they might inhibit polymerization. The use of a cavity varnish might prevent direct contact between the composite and the tooth structure, preventing bonding.

compositesWhen comparing the physical properties of filled resins to unfilled resins, all ofthe following are true EXCEPT one. Which one is the EXCEPTION?• Filled resins are harder• Unfilled resins have a higher coefficient of thermal expansion• Filled resins have a higher compressive strength• Unfilled resins have a lower modulus of elasticity• Filled resins have a lower tensile strength 49 copyright © 2016-2017 Dental DecksOPERATIVE

• Filled resins have a lower tensile strength***This is false; filled resins have a higher tensile strength.The most common classification method for composite resins is based on filler content, fillerparticle size, and the method of filler addition. Almost all important properties of compos-ite resins are improved by using higher filler levels. However, as the filler level is increased,the fluidity decreases.Highly filled resins typically contain large filler particles but this composition results in arough finished surface. Smaller filler particles, are used to produce a resin that has a rela-tively smooth finished surface.Resin filler particles are called: • Macrofillers: 10 to 100 microns (µm) in diameter • Midifillers: 1 to 10 microns in diameter • Minifillers: 0.1 to 1 microns in diameter • Microfillers: 0.04 to 0.1 micron in diameter. Examples include Dentacolor, Durafill, Heliomolar R.O., and Silux Plus.***Hybrid resins contain a mixture of particles with different diameters, which allows higherfiller levels and still permits good finishing. The principal particle size range from 1 to 3 µm.Examples include Charisma, Herculite XRV, Prodigy, Tetric, TPH (Total Performance Hy-brid), and Z100.Note: Hybrid and microfill resins utilize colloidal silica fillers, which are useful for in-creasing the hardness and wear resistance of the base resin material while maintaining high pol-ishability and overall esthetic qualities.***New resins with nanofillers that range in size from .005 to 0.01 micron have recently beendeveloped. These particles are so small that very high filler levels can be achieved while stillmaintaining workable consistencies. Supreme H-NF and Simile H-NF are examples.