Enamel Caries and Dentin Caries Perio ReportsVol. 26 … Caries and Dentin Caries ... oach that takes into consideration the baseline ... instructions were given at the clinical appoint-ment,

Enamel Caries and Dentin Cariespage 1

February 2014

Perio Reports Vol. 26 No. 2page 2

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»Inside This Issue2 Perio Reports5 Profile in Oral Health: Understanding the Caries Process:

Enamel Caries vs. Dentin Caries

Enamel Caries andDentin Cariesby Trisha E. O’Hehir, RDH, MSHygienetown Editorial Director

When I was a child, going to the dentist was a scaryand often painful experience. It was never a question of“did I have a cavity?” It was always “how many cavitiesdid I have?” Entering the dental hygiene field I soonlearned that dental disease was completely preventable.The goal is preventing the very first lesion – and keep-ing the mouth healthy for a lifetime is the expectation.This was a revelation to me as my entire family sufferedfrom dental disease.

Now, so many decades later, it’s surprising to methat the very idea that dental disease is preventable isnot widely known. It’s actually a well-kept secret.Dentists and hygienists know intellectually that dentaldisease is preventable, but why doesn’t the general pub-lic know this?

I’ve been having fun lately asking people I meet ifthey believe tooth decay is preventable. It is surprisingto learn that most people believe that dental disease isinevitable. They have fillings, their parents had fillingsand also lost teeth, so they fully expect their children tohave the same.

Statistics tell us that caries rates are higher amongthose at low socioeconomic levels. However, even whenI ask highly educated, financially successful people,they don’t believe dental disease is preventable. Theybelieve that dental disease is inevitable. Ask yourpatients, family and friends if they believe tooth decayis inevitable. See what answers you get.

Understanding the differences between caries inenamel and caries in dentin provide an opportunity tolook at prevention today and make changes for thefuture. Perhaps one day in the not-too-distant future,everyone will know that dental disease is preventableand that new approaches and technologies are availabletoday to make it a reality. n

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The general rule, although without scientific evidence, isto replace manual toothbrushes every two to three months.Some professionals suggest replacing the brush when thebristles become frayed, which can be a few weeks for someand a year for others, depending on their brushing force.

Researchers at the Academic Centre for Dentistry inAmsterdam compared new and used toothbrushes, with andwithout toothpaste, to determine plaque removal efficacy. Atotal of 45 subjects participated in the toothbrushing study.All subjects were non-dental students who routinely used amanual toothbrush.

At baseline, each subject was given a standard, four-row,multi-tufted toothbrush and instructed to brush with ittwice daily for three months. At that time they were sched-

uled to see the dental hygienist for professional toothbrush-ing and to measure toothbrush wear.

The RDH brushed each quadrant with a different tooth-brushing protocol: 1) new brush with toothpaste, 2) newbrush without toothpaste, 3) old brush with toothpaste and4) old brush without toothpaste. Pre- and post-brushingplaque scores were taken. Prior to the two-minute profes-sional brushing, the brush was moistened with cold waterand a timer set for 30 seconds for each quadrant.

When comparing different toothbrushes, an absolutedifference in plaque removal needs to reach 15 percent. Inthis study, the absolute difference was only five percent.There was no real difference between old and new tooth-brushes. Brushes with little wear outperformed new brushes

while worn toothbrushes were less effectivecompared to new brushes. Toothpaste pro-vided no benefit for plaque removal.

Clinical Implications: It’s not the age ofthe toothbrush, but the wear of the bris-tles that signals time for replacement. n

Rosema, N., et al: Plaque-Removing Efficacy of New and Used Manual Toothbrushes

- A Professional Brushing Study. Int J Dent Hygiene 11:237-243, 2013.

Reducing Patient Fear with a Direct Approach

About half of the adult population suffers from somedegree of dental fear, making it one of the most prevalent fears.In dentistry, there are three responses to a sense of danger: fear,phobia and anxiety. Dental fear is a reaction to a known dan-ger, provoking the “fight or flight” response, almost alwayscaused by a previous bad experience. Dental phobia is aresponse similar to dental fear, only much more intense anddebilitating. Dental anxiety is a reaction to an unknown or notimmediately present danger. It is often a consequence ofreceiving negative information without personal experience.

The psychological approach of direct interaction wasused in an attempt to reduce patients’ dental fear associatedwith a dental hygiene visit. A pre- and post-treatment ques-

tionnaire was given to patients who showed any level of den-tal fear. Using a zero to 10 scale, patients were asked how theywould rate: 1) fear of your last dental hygiene visit? 2) avoid-ance of today’s visit? 3) confidence in your last RDH?

The RDH explained procedures, asked what each patientliked and didn’t and showed them what she was doing. Post-treatment questions asked how the patient would rate: 1) fearof today’s visit 2) likelihood of avoiding their next dentalhygiene visit and 3) confidence in the RDH today.

No subjects reported more fear after the visit and 83 per-cent reported decreased fear after the visit. Modern dentistryshould not be a fear-inducing experience. Patients should betreated with empathy and dignity.

Clinical Implications: Dental fear can be reduced with a direct approach that takes into consideration the baselinefear of the patient. n

Roubalova, L.A.: Can a Patient’s Fear be Reduced Using the Psychological Approach of Direct Interaction? OHU Action Research 1A-13, 2013.

Perio Reports Vol. 26, No. 2Perio Reports provides easy-to-read research summaries on topics of specificinterest to clinicians. Perio Reports research summaries will be included in eachissue to keep you on the cutting edge of dental hygiene science.

Brushing with a New vs. Old Manual Brush

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Video Chats Improve Children’s Oral Hygiene Habits

Twice yearly dental hygiene visits do notprovide adequate coaching to help children andparents stay motivated to follow effective dailyoral hygiene. The introduction of new technol-ogy provides options for following up withpatients between visits. Weekly visits via Skypeor FaceTime may provide an option for videocoaching to improve oral hygiene habits.

For this project, five children (four boys andone girl) and their parents were recruited. Thechildren all had high plaque levels, high decayrate and lacked motivation. Their ages rangedfrom six to 13 years old. Thorough oral hygieneinstructions were given at the clinical appoint-ment, including brushing, interdental cleaningand diet suggestions. Permission was grantedfrom each parent to contact their child for a fol-low-up video chat. Parents were urged to partic-ipate in the video chat as well. During eachvideo chat, the children demonstrated how theybrushed their teeth and how they cleanedbetween their teeth. If technique changes wereneeded, the RDH would use a model to showproper technique. Diet was also discussed, aswell as methods that work best for each individ-ual patient and what goals they would strive tomeet before the next visit. The parents that didparticipate during each of the visits followedclose along and were involved in the goal-set-ting process.

Based on the results of a questionnaire forparents, the video chats had a positive impact.Each parent reported improvement in motiva-tion and technique. Four out of five reportedtheir child was brushing twice daily. Parentsalso reported taking a more active role in theirchild’s oral health. All parents and childrenwould like to continue with meetings viavideo chat.

Clinical Implications: Consider following upwith patients using video chat technology. n

Richey, C.: Using Technology to Improve Oral Hygiene. OHU Action Research 5A-

13, 2013.

The Feeling of Xerostomia vs. Clinical Hyposalivation

Hyposalivation is the objective measure of reduced saliva.Xerostomia is the subjective feeling of dry mouth. Increasingnumbers of medications produce hyposalivation as a side effect,leading to higher levels of dry mouth.

The Xerostomia Screening Questionnaire described byNavazesh was designed to identify patients with dry mouth, byassessing the most common, subjective complaints related toxerostomia. The Challacombe Scale of Oral Dryness uses clinicalimages of various stages of oraldryness to identify objective signsof hyposalivation.

Some individuals with salivarygland hypofunction are not awareof a reduction in the amount ofsaliva they feel in their mouths. Aproject was designed to compareobjective clinical oral drynessscores with subjective responsesto the xerostomia screening questionnaire. Twenty patients withclinical signs of oral dryness were asked to complete theXerostomia Screening Questionnaire. The dental hygienist com-pleted the Challacombe Scale for each patient.

According to the Challacombe Scale parameters, 55 percent ofthe participants had signs of moderate oral dryness and 45 percenthad mild oral dryness. Seventy percent of the questionnairerespondents reported too little saliva. Although 100 percent of theparticipants displayed clinical signs of oral dryness, 30 percentdenied experiencing any xerostomia symptoms.

Further research is needed to discover why people withreduced salivation don’t always feel the symptoms. It might also bethat the questionnaire did not contain questions that effectivelyreflected oral dryness symptoms. Screening should include bothobjective and subjective aspects of xerostomia.

Clinical Implications: Patients with clinical signs of dry mouthmay not actually be aware of a reduction in saliva. n

Douglas, L.M.: Investigating the Relationship between Clinical Oral Dryness Scores and Xerostomia Screening

Questionnaire Responses. OHU Action Research 11A-12, 2013.

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The role of the dental hygienist is to instill theneed, desire and ability for his or her patients toachieve optimum oral health. Too often the patient is not motivated to take an active role in their oral

health. They aren’t interested inwhat the hygienist is saying andunwilling to comply with oralhygiene instructions. They maynot see the value in what theyare being told. The result isongoing dental disease when itcould be prevented.

The purpose of this studywas to determine if patients correctly understood theoral hygiene instructions provided by their dentalhygienist and to see if RDHs feel they are givingpatients individualize instructions. A seven-questionelectronic survey was sent to 30 hygienists about recommendation and customization of oral hygieneinstructions. A similar seven-question electronic sur-

vey was sent to 30 non-dental professionals. Thesewere not the patients of the RDHs questioned, butrepresent an educated patient pool.

Of the RDHs, 57 percent responded. Whenasked if they offered alternatives to dental floss toclean interproximally, 100 percent answered affirma-tively. Of the non-dental professionals, 46 percentresponded to the survey. When asked a similar ques-tion about whether their RDH offered an alternativeto flossing, only 29 percent answered yes.

These findings reflect the disconnect betweenwhat RDHs believe they are conveying to theirpatients and what the patients actually hear. Based onthese findings, communication and motivationalinterviewing should include the patient in their oralhealth-care decisions and oral hygiene care routines.

Are Hygienists as Effective as They Think They are with Oral Hygiene Instructions?

What Does it Take for Patients to Change Behavior?

Dental health-care providers expend significant effort tohelp each patient achieve better oral health through preven-tion. The problem is many patients are not very good atcomplying with the recommendations offered to them. Theyfrequently return with the same problems and no real changein their oral hygiene.

The purpose of this study was to determine if a simplefollow-up contact would impact behavior change in a groupof 18 patients. For each patient, a specific oral hygiene rec-ommendation was given, based on their individual needs.Included were flossing, antibacterial rinses, interdentalbrushes and picks.

Contact was made with the patients one week after theirroutine dental hygiene appointment. They were contactedvia text messaging or e-mail, based on their preference.

Nineteen patients agreed to be part of this study and theywere sent a short three-question survey. The patients wereasked if they tried the specifically recommended item, if theyliked using it, why or why not. The response rate was 50 per-cent. Those who responded did state that they tried the rec-ommended product, but only 33 percent of the patients feltthey would continue to use the recommended product.

This action research project showed that in a group ofwilling participants, only one-third changed their behavior.The author concluded from this study that follow-up contactalone is not an effective method to change behavior and doesnot increase compliance with oral health recommendations.

Clinical Implications: More is needed than one clinical interaction and a single follow-up contact to ensure behaviorchange in patients when new oral hygiene instructions are given. n

Huber, M.: Does Follow-up Contact Increase Patient Compliance with Oral Hygiene Recommendations? OHU Action Research 5A-13, 2013.

Clinical Implications: Patients do not always hearand understand what RDHs believe they providein their instructions to patients. n

Byrne, C.: Can Patients Achieve Better Oral Health Through Motivational Interviewing.

OHU Action Research 5A-13, 2013.



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IntroductionEnamel is the hardest substance in the human body. It is in

a constant state of flux, going back and forth from demineraliza-tion to remineralization. Every time there is a drop in the oralpH below 5.5, enamel demineralizes. Drinking orange juice,wine or soda will demineralize the enamel. Remineralizationthen occurs with the help of salivary minerals and bufferingagents. This natural ebb and flow can be disrupted by continu-ous exposure to acid, usually in areas protected from the rem-ineralizing benefits of saliva. When bacterial biofilm covers pitsand fissures and interproximal sites, the acid is held against thetooth surface with no remineralization possible. The demineral-ization affects enamel, eventually visible as white spot lesions.The next step is cavitation and eventually the demineralizationmoves into the dentin.

At this point, the process changes. Bacteria-produced acidsbegin the demineralization process in the dentin, and then endoge-nous, zinc-dependent proteases destroy the dentin. The bacteria areresponsible for the initial demineralization and destruction ofenamel, but then substances within the body that are often benefi-cial become destructive to the dentin. This two-phase destructionof tooth structure requires a variety of preventive approaches.

Traditionally, the focus was to protect the enamel with fluo-ride and by disrupting bacterial biofilm formation and reducingthe consumption of fermentable carbohydrates. Based on newscientific findings, additional strategies are needed to inhibit thedestructive actions of proteases, specifically the family of Matrixmetalloproteinases (MMPs). Better understanding the cariousprocess from enamel through dentin will provide new optionsfor preventing and reversing carious lesions.

Caries in EnamelPlaque biofilm is composed of a multitude of bacteria

including Streptococcus, Lactobacillus and Actinomyces species.Oral bacteria convert carbohydrate foods and drinks in themouth for their own energy through a process of fermentation.Lactic acid is a byproduct of this fermentation process and witha pH below 4 is capable of demineralizing enamel. This acidifi-cation of the biofilm causes demineralization of enamel. Theacidification of the biofilm provides an environment conduciveto the proliferation of acidogenic and aciduric bacteria, thosethat prefer a low pH environment and those that produce lacticacid. As long as the environment continues with a low pH,enamel demineralization will continue. No disruption of thebiofilm and continued acid production will lead to more dem-ineralization and eventual cavitation.

A constant source of fermentable carbohydrates feeds theseacid-producing bacteria. Although often referred to as “sugar

bugs,” it’s not just sucrose or table sugar that leads to acid produc-tion. Hydrolyzed starches can be fermented to produce lactic acidas well. These starches are long chain sugars that contribute toacid production. Potato chips, pasta, bread and other starches willall provide the nutrients necessary to continue the caries process.Although sucrose is the primary factor, hydrolyzed starches arealso considered fermentable carbohydrates.

Caries in DentinThe carious process within dentin differs from that in

enamel. Dentin is less mineralized, containing 20 percentorganic material compared to only one percent in enamel. Thebacteria-produced acids that dissolve enamel will also dissolvethe dentin mineral, uncovering the organic dentin extracellularmatrix (ECM). Proteases are then responsible for degradation ofECM, allowing the movement of bacteria toward the pulp. Thetubular nature of dentin enhances this movement of bacteria. It was long thought that the proteases degrading the ECM were produced by the bacteria, but recent findings suggest that bacterial proteases cannot withstand the drop in pH that oftenreaches 4.3.

New theory suggests that host-derived, zinc-dependent pro-teases, specifically Matrix metalloproteinases (MMPs) foundwithin dentin and saliva, are responsible for the degradation ofdentin. MMPs are involved in both normal and destructiveactions throughout the body. MMPs consist of a family ofendogenous proteolytic enzymes. Some are associated with dentogenesis and others are capable of degrading dentin. ActiveMMPs have been found in demineralized dentin, suggestingthey can disorganize and degrade the dentin matrix. MMPsrequire metal ions, specifically zinc, for activation. Strangely, theMMPs must be activated, often by acids, but then require a neu-tral pH to destroy the matrix components. The bacteria-pro-duced acids can activate the MMPs and it’s thought that salivarybuffers then allow dentin destruction by the MMPs.

Examination of extracted, carious teeth shows a gradualchange in the gelatinous texture of the dentin. The continuumincludes a superficial soft carious lesion, an inner soft cariouslesion, affected dentin and sound dentin.

The Caries/Diet ConnectionToday’s diet no longer includes three meals and a snack after

school, as was the trend years ago. Today, fermentable carbohy-drates are consumed continuously throughout the day and intothe evening. Snacks and fizzy drinks are readily available all daylong. This contributes to the “ecological plaque hypothesis”introduced by Drs. Takahashi and Nyvad that the pH of theplaque biofilm determines disease activity. High intake of fer-

Enamel Caries vs. Dentin Caries by Trisha E. O’Hehir, RDH, MS




mentable carbohydrates will favor acid production and prolifer-ation of acid-producing oral bacteria. Changing the diet byreducing the intake of fermentable carbohydrates can elevate thepH, shifting the ecology of the biofilm to one more conduciveto health.

Introducing oral probiotics may shift the balance of bacteriain the mouth to those preferring a higher pH. Competitionbetween established acid-producing bacteria and specific speciescontained in oral probiotics leads to metabolism of lactic acidinto hydrogen peroxide, which will inhibit S mutan growth.Xylitol also interferes with the sucrose glycolosis. Xylitol is afive-carbon molecule, not six like sucrose. The smaller molecu-lar size allows xylitol to pass through the outer cell wall of thebacteria easily, but it is not the right molecular structure to beused by the bacteria to produce energy. The bacteria must thenuse its own energy to pump the xylitol molecule out via a mem-brane pump. This process expends energy without providing anenergy source for the bacteria. Xylitol also blocks the communi-cation between bacteria, interfering with quorum sensing, a keyfunction in the formation and maintenance of biofilm structure.Without mechanical disruption of bacterial biofilm, three to fiveexposures to xylitol daily will reduce bacterial biofilm levels byapproximately 50 percent.

Preventive Strategies Now and in the FutureUntil now, caries prevention has focused on enamel caries,

with no specific approaches to prevent dentinal caries.Control of diet, adequate biofilm removal and fluorideexposure are components of the current approach tocaries prevention.

MMP inhibitors may be the next level of preventionfocused on prevention of dentin demineralization. Research isnow being done to determine if the use of chemical or naturalMMP inhibitors can control caries progression within dentin.The tetracycline family of antibiotics can inhibit MMPs, sep-arate from their antimicrobial properties. Zoledronate, a thirdgeneration bisphosphonate, is also a potent MMP inhibitor.However, these drugs are used systemically and a better choicewill be a topical product. Chlorhexidine as well as Ethylene-diaminetetraacetic acid (EDTA) will impair MMP activityand can be used topically.

Other potent MMP inhibitors come from natural sources,including green tea polyphenols and grape seed extract. Grapeseed extract suppresses lipopolysaccharide-induced MMP secre-tion by macrophages. Grape seed extract was shown in labora-tory studies to both inhibit demineralization and promoteremineralization of artificial root caries lesions. Both chemicaland natural ingredients can be incorporated into oral rinse andtoothpaste products in the future.

ConclusionThe caries process involves destruction of both enamel and

dentin, with a combination of damaging actions. Preventionand remineralization are two critical approaches to address withnew scientific knowledge and modern technologies. Preventionand remineralization of early lesions are possible using both tra-ditional and contemporary approaches. n

To comment on this article, visit Dentaltown.com/magazine.aspx.

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Enamel Caries and Dentin Caries Perio ReportsVol. 26 … Caries and Dentin Caries ... oach that takes into consideration the baseline ... instructions were given at the clinical appoint-ment,