Minimal Intervention Dentistry: A New Focus for Dental Hygiene

Minimal intervention dentistry (MID) uses a medical model of disease control by the dental team, including an oral physician and dental hygienist.1-3 The main components of MID are as follows: disease risk assessment with early detection and prevention; external and internal remineralization therapy; use of a range of restorations, dental materials, and equipment; and surgical intervention only when required after disease is controlled.1-3 Caries management in MID involves the assessment and management of a diverse group of patient modifying factors and primary factors, integrated with an evaluation of the plaque/biofilm interface and the resultant dynamic oral disease process (Figure 1).4 Formats for conducting this assessment include CAMBRA and Ngo’s Traffic Light system.4,5

Figure 1. MID caries management (modified from Ngo in Mount and Hume, 2005).4

It is essential to assess the clinical pattern of demineralization and caries in the context of all modifying, primary, and biofilm factors. Within the mouth of an adult who has active and even rampant caries, there will be a range of low to high areas of demineralization and caries (with and without cavitation), as the process of demineralization and remineralization is continuous. The focus of the dental hygienist in MID is on much more than periodontal diseases; hygienists are central to the coordination of patients’ oral disease assessment, treatment, and management. MID helps to establish a positive professional model of comprehensive dental care provision for clinical practice. Key to MID success is the contribution of the following from the dental hygienist:

  • identification of oral diseases and associated risk factors (risk assessment)
  • saliva testing
  • oral microbiological testing
  • use of dental products
  • monitoring of patient compliance
  • clinical prophylaxes and professional therapeutic treatments
  • regular recalls.

PRIMARY FACTORS: SALIVA

Table 1. The Xerostomia Inventory (XI).7,9
Please circle the answer that best applies to you during the last year.
1. I sip liquids to aid in swallowing food.
NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
2. My mouth feels dry when eating a meal.
NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
3. I suck candy to relieve dry mouth NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
4. My lips feel dry NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
5. I have difficulties swallowing certain foods NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
6. My mouth feels dry NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
7. I get up at night to drink NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
8. My eyes feel dry NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
9. I have difficulty eating dry foods NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
10. I have difficulty swallowing NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW
11. The skin on my face feels drry. NEVER HARDLY EVER OCCASIONALLY FAIRLY OFTEN VERY OFTEN DON'T KNOW

 

Table 2. Treatment of Xerostomia and Salivary Gland Hypofunction.
General Treatment Saliava ubstitutes and Oral Lubricants Saliva Stimulants
  Use several times daily as needed, including before meals and bedtime. Useful only if salivary gland tissue remains.
Change medications to classes that are less anticholinergic and fluid retaining Oral Balance Gel, Denture Grip, and Biotene Range: mouthrinse, toothpaste, and gum (Laclede) Chewing sugar-free gum and candy several times daily, eg, xylitol gum and candy products, Trident White with Recaldent Gum
Increase water intake (if not contraindicated by medications and medical conditions) MI Paste/MI Paste Plus (GC America)
Not to be used in people with an IgE casein allergy but can be used with lactose intolerance.
Salivaure tablets (Scandanavian Formulas) Place several times daily near major salivary ducts and suck. Contain fruit acid that is pH-buffered.
Avoid dental products with additives (eg, sodium lauryl sulfate) or alcohol (eg, mouthrinses) Range of other products such as Moi-Stir (Kingswood Laboratories) and MouthKote (Parnell Pharmaceuticals) Systemic sailogogue therapy with pilocarpine or cevimeline. May have adverse effects.
Use a room humidifier during the day and at night    

When patients have “dry mouth,” a variety of terms are used and confused when describing their problems. Xerostomia is the subjective self-perception of dry mouth.6,7 Salivary dysfunction or salivary gland hypofunction (SGH) is present when the quality and/or quantity of saliva changes.6-9 The xerostomia inventory (XI) can be used to assess xerostomia, with higher scores indicating worse xerostomia7,9 (Table 1). Simple assessment of saliva function can be conducted using a short, systematic method described by Ngo and Walsh.4 Several testing kits are available commercially, such as Saliva Check (GC America), which assess unstimulated and stimulated saliva flow rates and pH as well as buffering capacity. The management of xerostomia and SGH is difficult and multifaceted. Clinicians can use results from the xerostomia inventory and saliva testing to help guide them toward the use of saliva substitutes versus stimulants (secretagogues), and other strategies7-9 (Table 2).

PRIMARY FACTORS: DIET AND XYLITOL

It is desirable to minimize patients’ high-frequency consumption of fermentable dietary substrates, including those in foods, drinks, and medications.10 Nonfermentable dietary sweeteners are recommended wherever possible, such as xylitol, sorbitol, aspartame, or saccharin.10 The polyols such as xylitol are anticariogenic, as they result in decreased acid fermentation by S mutans.11 Findings vary from evidence-based reviews of xylitol, but it is recommended to use 6 grams per day of xylitol for caries management.11,12

PRIMARY FACTORS: FLUORIDES AND CALCIUM PHOSPHATES

Fluoride acts in 3 ways: it inhibits demineralization, it increases enamel resistance to acid attack and remineralization via formation of fluoride-enriched apatite, and at high concentrations it can inhibit bacterial metabolism.13 Frequent fluoride exposures maintain optimal, low-level loading of the salivary fluoride reservoir.14
Sodium fluorides are generally recommended in adult patients due to the detrimental effect of stannous and acidulated fluorides on restorative materials—staining, removal of glaze from ceramics, and roughening of composites and glass ionomers.13 Low-caries risk adults can use a 1,000 ppm toothpaste, which can be supplemented or replaced as caries risk increases with a 5,000 ppm prescribed toothpaste or gel. The use of sodium fluoride mouthrinses is decreasing with the introduction of the 5,000 ppm toothpastes, as is the use of fluoride foams (placed in trays) at 12,300 ppm, with greater use of 22,600 ppm (5%) fluoride varnishes.15
Although the use of topical fluorides has resulted in decreased caries experience in many adults and older adults, some always experience high caries rates despite the use of fluoride.13 These patients need additional adjunctive therapies for saliva dysfunction, use of chemoprophylactics, and use of calcium phosphates. Remineralization from fluoride ions is more superficial than that of calcium, phosphate, and fluoride ions in combination; there is potential for calcium phosphate products to enhance remineralization synergistically if incorporated with topical fluoride use.16
The use of calcium and phosphate products for remineralization commenced commercially with the development of the ADA Foundation ACP products. The first of these was Enamelon (in 1999), a dual-compartment system that separated the components calcium sulfate and dipotassium phosphate until application intraorally. A newer version of this ADA Foundation ACP product has been recently remarketed by several companies with a specific focus on desensitization and bleaching.17 Some clinicians have also used pharmacy-formulated calcium and phosphate rinses with their patients for many years. Recently, sophisticated carriers for calcium and phosphate such as the casein protein molecule (CPP-ACP) and bioactive glasses (NovaMin [NovaMin Technology]) have been developed to improve upon the application technology of the earlier calcium phosphate products. NovaMin is a sodium calcium phosphosilicate glass that releases calcium and phosphate ions in water and/or saliva. Sodium ions in the NovaMin particles exchange with hydrogen cations; this then allows calcium and phosphate ions to be released.18 A calcium phosphate layer is formed, which then crystallizes into hydroxycarbonate apatite.19 The physical occlusion of dentinal tubules results from both the hydroxycarbonate apatite layer and the residual NovaMin particles.18
Several NovaMin products are marketed that focus on hypersensitivity, and newer products focus on remineralization. There is a building evidence base of clinical studies, mainly from the NovaMin company, supporting the desensitizing action of these products. This product does have FDA approval for hypersensitivity; clinical protocols are evolving for the use of NovaMin products.

Figure 2. Remineralization of enamel with fluoride and Recaldent at differing concentrations: (a) demineralized enamel; (b) remineralized enamel with 1,000 ppm fluoride + 7% mineral; (c) remineralized enamel with 2% CPP-ACP + 13% mineral; (d) remineralized enamel with 2% CPP-ACPF + 21% mineral. (Images courtesy of Professor Laurie Walsh and GC Asia, 2007; microradiographs-in situ testing, University of Melbourne.)

Recaldent (CPP-ACP (Bonlac Bio-science International) was developed at The University of Melbourne, Australia, during the 1980s and 1990s, with more than 60 peer-reviewed papers and 55 abstracts published on Recaldent in vitro and in vivo research. Stabilization of nanoclusters of amorphous calcium phosphate (ACP) with casein phosphopeptides (CPP) results in localization of CPP-ACP at the tooth surface by binding to dental plaque (to the microorganisms and in the extracellular matrix) and binding to exposed dentin.16 CPPs are “activated” in an acidic oral environment and buffer plaque pH to produce calcium and phosphate ions, in particular the neutral ion pair CaHPO4O, which is highly correlated with the rate of enamel remineralization and prevention of demineralization.16 CPP-ACP interacts with localized fluoride ions to produce a novel amorphous calcium fluoride phosphate phase. Figure 2 presents several representations of differences in the depth of enamel remineralization with varying fluoride and Recaldent products. Thorough remineralization will take time to occur with Recaldent products.
Recaldent is sold professionally as GC America’s MI Paste (10% CPP-ACP) and MI Paste Plus (10% CPP-ACP and 900 ppm [0.2%] sodium fluoride), and in a consumer range of chewing gum products (Trident White with Recaldent [0.6% CPP-ACP]; Cadbury Adams). At present, the most peer-reviewed evidence is for Recaldent and the chewing gum, with increasing in vitro and in vivo research being published about MI Paste. MI Paste Plus, the newer product, has limited peer-reviewed research published at present. Due to the casein content, all potential users of Recaldent products must be asked if they have an IgE mediated casein allergy, ie, “Do you ever have any allergic reactions when you drink milk?”16 Recaldent products can be used by patients with lactose intolerance as they do not contain lactose.16
Clinical in-office and at-home protocols for the use of Recaldent products are continually evolving.20 Patients can use MI Paste, MI Paste Plus, the gum, or combinations several times daily. The preferred method of application is to place a pea-sized amount of MI Paste/MI Paste Plus on a fingertip and rub it all over teeth and soft tissues. A toothbrush is not generally advised for application, to optimize the substantivity and release of calcium and phosphate into the saliva, except in banded orthodontic patients who may find it difficult to apply it with their finger.20
Clinical indications for Recaldent products are hypersensitivity, pre- and post-bleaching and periodontal scaling to help reduce sensitivity, erosion, caries prevention and remineralization, demineralization around orthodontic brackets, and dry mouth.16,20,21 In adults with salivary gland hypofunction, MI Paste can be used as a saliva substitute/enhancer.16,20-22 An application of MI Paste can also help lubricate and comfort a dry mouth before commencing dental treatment.20 This product does have FDA approval for hypersensitivity and is used off-label for other indications.
Also, a remineralization protocol can be used after orthodontic treatment if white-spot lesions are present around brackets.23 A diagnostic 47% phosphoric acid etch for 15 seconds is initially used to detect any excess bonding agent remaining on the enamel. After all excess bonding agent is removed, 2 rounds of the following treatment are completed: 15-second 47% phosphoric acid etch immediately followed by prophylaxis with paste. For heavier, deeper lesions such as those seen in fluorosis, a 2-minute etch may be needed prior to prophylaxis with paste. Then, apply MI Paste all over the teeth for 5 minutes, then have the patient apply MI Paste 1 to 2 times daily after brushing with toothpaste. Several more rounds of this treatment may be needed at weekly intervals.23 Please note that if using 1,000 ppm toothpaste, either regular MI Paste or MI Paste Plus can be used. However, if using 5,000 ppm toothpaste for a high-caries patient, only use regular MI Paste.


PLAQUE/BIOFILM INTERFACE: CHEMOPROPHYLACTICS
The management of oral microorganisms with chemicals has historically focused on plaque control, especially for periodontal diseases, more than dental caries.24 Products have generally been approved by regulatory bodies for on-label plaque-control use, with off-label use for dental caries. Chemoprophylactic agents are those most commonly used for oral disease management and can be categorized by their ionic status:

  • cationic—including chlorhexidine gluconate (CHX), cetylpyridinium chloride (CPC), benzalkonium chloride, hexetidine, and metal salts
  • anionic—sodium lauryl sulfate
  • nonionic—phenolic compounds (essential oils) and triclosan.

Additional categories include oxygenating agents (hydrogen peroxide) and surface-modifying agents (delmopinol).24
CHX is the most accepted and widely used chemoprophylactic due to its substantiveness and low toxicity, and the most prevalent CHX product is the 0.12% mouth-rinse with or without alcohol. A nonalcohol CHX rinse has been marketed in North America by Sunstar Butler (Sunstar Americas). Evidence has substantiated that nonalcohol CHX products are as effective as those with alcohol.25 The use of a small spray bottle is an effective alternative application method for CHX mouthrinse for older or disabled patients.26 CHX recommendations for management of dental caries may range from daily to weekly use. Duration will vary depending upon oral microorganism monitoring and appearance of new caries. Be aware of potential CHX adverse effects, especially if the patient has dry mouth; use a nonalcohol-containing CHX and reduce frequency of application. Although past recommendations have often specified the use of CHX twice daily, periodontal disease and caries management may be achieved with once daily use.27,28 Potential interaction with fluoride is possible, especially with toothpastes containing sodium lauryl sulfate.29 Application regimens can take this into consideration: apply CHX after lunch and apply fluorides in the morning and evening; or apply CHX in the morning and fluoride at night, or vice-versa.

WHICH PRODUCT FIRST?

Table 3. Examples of MID Therapy Protocols for Adult Patients.
Adult patient example Toothpaste Recaldent product (MI Paste, MI Paste Plus,* or Trident White Gum) and other saliva dysfunction products Chlorhexidine gluconate 0.12% mouthrinse (rinse or spray bottle(, no-alcohol preferred Fluoride varnish 22,600 ppm
Low caries risk and hypersensitivity 1000 ppm 2 times daily Use MI Paste/MI Paste Plus and/or gum several times daily (including after brushing) for hypersensitivity Not needed 1 to 2 times annually as required
Hypersensitivity and bleaching 1000 ppm 2 times daily Use MI Paste/MI Paste Plus for 2 weeks before/after and during bleaching; brush teeth with toothpaste then use MI Paste; wait one hour before daily nighttime bleaching Not needed 1 to 2 times annually as required
High caries risk (soda, diet, drug abuse, radiation treatment, GERD, etc) and saliva dysfunction 5000 ppm (or 1000 ppm if using MI Paste Plus) 2 time daily (morning and night) Use MI Paste and/or gum several times daily (including after brushing) for saliva dysfunction and caries Once daily after lunch 4 weeks, then review oral bacteria and caries rate Several times annually
Prevention of white-spot lesions related to orthodontic banding 1000 ppm 2 times daily Use MI Paste/MI Paste Plus several times daily (including after brushing) for prevention of demineralization and caries As needed of cavitated carious lesions present Several times annually
* If using MI Paste Plus, only use with 1000 ppm fluoride toothpaste.

Achieving good compliance is always a challenge. Table 3 presents an example of clinical protocols for the use of preventive products in MID. When deciding which preventive or therapeutic product to prescribe, it is advisable to do the following: review the oral diseases and patient problems present and the greatest modifying factors contributing to them; try one product first; add products over time; and have ongoing adjustment and review of the oral hygiene protocol.20 If active caries is present, two main product categories to try first are those for saliva dysfunction and chemoprophylactics. Use of Recaldent products will be beneficial for both dry mouth and caries. If a patient has high caries experience, then also recommend a 5,000 ppm to