Wednesday, August 26, 2015

Assessing patients’ caries risk

Resident’s Name: Semantha Charles Date: 08/26/2015
Article Title: Assessing patients’ caries risk
Journal: JADA, Vol. 137
Author: Margherita Fontana, DDS, PhD; Domenick T. Zero, DDS, MS
Date:  September 2006
Major Topic: how to apply risk assessment models to adult populations
Main Purpose: Changes in the modern management of caries.

Key Points/Summary:
Because caries is a multifactorial disease, the incorporation of caries risk assessment into the concept of caries management should include factors that may affect caries development, such as past and current caries, diet, fluoride exposure, presence of cariogenic bacteria, salivary status, general medical history and sociodemographic.
The preventive and restorative caries management plan and frequency of recall visits should depend on a patient’s caries risk.
The risk assessment, any proposed management strategy and outcomes should be recorded formally over time to monitor and measure treatment efficacy.
Caries risk assessment determines the probability of caries incidence (that is, number of new cavities or incipient lesions) in a certain period.
It also involves the probability that there will be a change in the size or activity of lesions in the mouth.
Determining caries activity may be a stronger predictor of caries risk than decayed, filled or missing teeth. 
The detection of frank cavitations in teeth requiring restorations has been a hallmark of dentistry. In contrast, modern caries management also focuses on the detection of incipient, noncavitated lesions and the practitioner’s ability to diagnose whether those lesions are active. 
An active carious lesion progresses over time and requires management (remineralization or restoration). 
An inactive lesion may be visible either clinically or radiologically (like “scar tissue” that reminds us of past damage to the tooth), but it will not progress or change over time.
Arrested or remineralized lesions do not require intervention since they do not represent active disease, unless the lesions are so advanced that they interfere with oral function or esthetics.
Any patient with active disease faces an increased risk of developing the disease in the future.
Patients who do not have active disease or clinical signs of caries are not necessarily at low risk of developing the disease. 
For example, life stressors such as leaving home for college for the first time, having orthodontic brackets placed on teeth or experiencing other significant life events can affect caries risk.
Caries risk indicators include: 
Bacteria and oral hygiene: The microbial component of caries can be viewed from the perspective of specific microorganisms that contribute to the disease, or whole plaque.
Specific organisms: Available bacterial salivary tests could be used to determine cariogenic bacteria in the mouth and perhaps motivate patient behavioral changes.
Whole plaque: Because plaque is one of the main etiologic factors for caries, it is important to estimate the number of surfaces affected, the amount of plaque accumulated, the age of the plaque and whether the presence of plaque is associated with the presence of carious lesions in those same sites.
Saliva: A chronically low salivary flow rate has been found to be one of the strongest salivary indicators for an increased risk of developing caries.
Diet: diet alone is an inadequate indicator of caries risk. Other risk factors also need to be considered, such as assessing a patient’s pattern and frequency of carbohydrate intake and its relationship with oral hygiene habits. 
Exposure to fluoride: fluoride use, which can be considered one of the most important protective factors when assessing a patient’s caries risk, allows more conservative management strategies for the prevention and treatment of caries.
Past caries experience: This single caries risk indicator provides the greatest predictive ability. The presence of caries in the mother increases a young child’s risk. Caries prevalence in primary teeth can help predict future caries in permanent teeth. In adults, there is an association between existing caries and the risk of developing root caries.
Medical and demographic factors: 













Caries risk in formerly sealed teeth


Department of Pediatric Dentistry

Lutheran Medical Center

 

Resident’s Name: John Diune                                                                                             Date: 8/26/15

Article Title: Caries risk in formerly sealed teeth
Author(s): Griffin, Gray, Malvitz, Gooch
Journal: JADA
Date: April 2009
Major Topic: Dental Sealants
Type of Article: Systematic review of articles
Main Purpose: Examine risk of caries development in teeth with partially or fully lost sealants (formerly sealed FS teeth) compared to risk in teeth never having sealants (never-sealed NS teeth)
Key Points/Summary:
  • Literature search with inclusion criteria requiring randomized controlled split-mouth designed studies using resin-based sealants with no reapplication of lost sealants containing sufficient data to estimate caries risk in FS teeth relative to NS teeth ([RR]=[%FS developing caries]/[%NS developing caries]) and its 95 percent confidence interval (CI)
  • 5 systematic reviews (which included 37 unique studies) included, total 7 studies included in review; 30 studies excluded
  • Almost 70% youth experienced dental caries by late adolescence; low-income families (income <200% of federal poverty guidelines) are more than 2x as likely to have untreated caries in permanent teeth
  • ~90% of all caries in pits and fissures of permanent teeth
  • Truman et al has shown that dental sealants delivered in clinical or school settings reduce caries in pits and fissures by 60% from 2-5yrs after placement
  • National data indicate sealant prevalence ~30% (below National Healthy People 2010 target of 50%)
  • Task Force on Community Preventive Services (members appointed by director of CDC) issued strong recommendation that school-based sealant programs be part of comprehensive community strategy to prevent dental caries
  • Potential concern to delivery of sealants is concern that teeth w/ partially lost sealant may be at higher risk of developing caries than NS teeth – thus CDC-sponsored Expert Work Group tasked with carrying out analysis
  • Results:
    • After 1 year: RR ranged from 0.828-1.118 (mean 0.941)
    • At 2 years: RR ranged from 0.467-1.186 (weighted mean 0.912; 95%CI 0.793-1.048)
    • At 3 years: RR ranged from 0.761-1.111 (weighted mean 0.901; 95%CI 0.789-1.029)
    • At 4 years: RR ranged from 0.693-1.083 (weighted mean 0.936; 95%CI 0.896-0.978)
    • All years mean RR <1
  • Discussion:
    • Individual teeth w/ partial or complete loss of sealant not at higher risk of developing caries than if they were never sealed
    • Caries rate in FS teeth is less than or equal to rate in NS teeth
    • In all but 1 study, RR of caries for FS teeth w/ partially lost sealants vs NS teeth was lower than the RR of caries for FS teeth with either partially or fully lost sealants vs NS teeth, in remaining study it was the same; findings suggest heightened concern about partially lost sealants trapping food and increasing caries risk is unfounded (but possibility that studies did not have sufficient sensitivity to detect difference
    • Benefits of delivering sealants to children whose follow-up is uncertain exceed potential risks
 
 
 
 
 
 
 
 
 
 
 
Assessment of Article: Efficient method of analyzing high number of articles addressing specific question
Level of Evidence/Comments:  I
 
 
 
 
 
 
 
 
 
 

 

Mechanical and Chemotherapeutic Home Oral Hygiene


Department of Pediatric Dentistry
Lutheran Medical Center

Resident’s Name: John Kiang                                                                                         Date: 8/26/15
Article Title: Mechanical and Chemotherapeutic Home Oral Hygiene
Author(s):  Dean and Hughes
Journal: Dentistry for the Child and Adolescent
Date: 9th Edition
Major Topic: Homecare
Type of Article:  NA
Main Purpose:  Discuss proper homecare techniques and research associated
Key Points/Summary:
Microbial Aspects of Oral Hygiene and Plaque Formation:
700 Bacterial species and numerous distinct bacterial habitats in the mouth
Plaque control, mechanical plaque removal with supplementation by chemotherapeutic agents currently offers the most practical method of controlling plaque
Pathogenicity of plaque is related to the numbers of Strep mutans and related species.
Plaques associated with gingival inflammation are characterized by a dominance of gram-negative bacteria.
Plaque control has two goals: 1. Limiting the numbers of mutans strep in dental plaques for prevention of caries by mechanical elimination of supragingival plaque and limitation of dietary sucrose and 2. Maintaining the predominantly gram-positive flora associated with gingival health by mechanical removal of plaque from the subgingival area.
Mechanical Methods of Plaque Control:
Manual Toothbrush: Most common is synthetic nylon bristles with bristle length of 11mm and can be characterized as soft (0.16 to 0.22mm), medium (0.23 to 0.29) or hard (0.30 greater).
Soft TB is preferable for decreased trauma and a smaller head with thicker handle (no design has been proven to be better than another).
Brushes typically wear at about 3 months, but more so with younger children, as they tend to bite bristles etc.
Floss: Corby and colleagues found that after a 2 week study of 12 to 21 year old matched twins, tooth and tongue brushing plus flossing significantly decreased the abundance of microbial species associated with perio disease.
No diff between floss and floss devices for removing plaque. However unwaxed nylon-filament floss has generally been considered floss of choice.
Powered Mechanical Plaque Removal: Powered brushes should decrease the need of dexterity by automatically including some movements of the toothbrush head.
For adults, studies suggested that results for plaque removal over time were comparable to manual tb.
The Sonicare tb was shown to be significantly more effective at removing plaque than the manual tb (Ho and Niederman)
Studies concluded that the powered tb removed sig. more plaque than manual tb in children.
Dentifrices: Act as plaque and stain removing agents through the use of abrasives and surfactants.
Dentifrices have anticaries and desensitization properties through the action of fluoride and other agents.
Ingestion is likely a substantial source of systemic fluoride for children and may put children at risk for fluorsis (Levy et al. children 0-6 years.) –why we should recommend smear and pea size
Simard et al concluded from their study of 12-24 month old children that 20% of children ingested more than 0.25mg of fluoride per day from tb alone.
Recc: low fluoride tp for infants or reduce the diameter of the tube (commercials not showing parents putting on globs of tp)
Disclosing Agents: Most commonly used is FDC red No. 28. Evidence shows that these agents are helpful in measuring a patients oral hygiene abilities, one must assess plaque deposits immediately after the patient has cleaned their teeth.
Techniques for Plaque Control:
Brushing Techniques:
Roll Method- brush in vestibule and bristle ends are directed apically and brush is rolled to the occlusal
Modified Sillman Method – combines vibratory action of bristles with stroke movement along the long axis of tooth.
Horizontal Scrubbing  - The brush is placed horizontally on buccal and lingual surfaces and moved back and forth with scrubbing motion (studies suggest this method removes the most plaque and is the most natural for children).
Flossing: 2 feet in length wrapped around patients/parents middle fingers and allow thumbs to guide gently through contact.
8-11 year old children in a study learned how to use dental floss within 10 days
Time Considerations: Hodges et al. studied brushing with tp for 30, 60, 120 and 180 seconds, and results showed that 1 minute brushing provides the greatest plaque removal benefit
Antiseptic: Chlorhexidine, positively charged organic antiseptic that binds anionic glycoprotiens and phosphoproteins on buccal and palatal pellicle (causes cell wall membrane permeability). Can cause staining, impaired taste sensation, increased supragingival calculus formation.
Listerine – high alcohol content (25%). Proven to reduce plaque and gingivitis indices. 4-year-old boy died after consuming 12oz of 10% alcohol mouthwash.





Nutritional Consideration for the Pediatric Dental Patient

Department of Pediatric Dentistry
Lutheran Medical Center

Resident’s Name:                                                                                                        Date:

Article Title: Nutritional Consideration for the Pediatric Dental Patient
Author(s): Laura Romito and James McDonald
Journal: Dentistry for the Child and Adolescent
Date: 2011
Major Topic: Nutrition
Type of Article: Chapter
Main Purpose: Nutritional Considerations
Key Points/Summary:

The Dietary Guidelines for Americans support the objectives in Healthy People 2010 and include the following recommendations:
·      Aim for fitness
·      Aim for healthy weight
·      Be physically active each day
·      Build a healthy base
·      Let the Food Guide Pyramid guide your food choices
·      Choose a variety of grains daily
·      Choose a variety of fruits and vegetables daily
·      Keep food safe to eat
·      Choose sensibly
·      Choose a diet low in saturated fat and cholesterol and moderate in fat
·      Choose beverages and foods so as to moderate your intake of sugars
·      Choose and prepare foods with less salt
·      Drink alcohol in moderation

Dietary Patterns

In comparing food intake trends among children ages 6 to 11 years old from 1977 to 1998, there was a reported increase in consumption of soft drinks, grain products, fried potatoes, non-citrus juices, cheese, candy, and fruit drinks and aids. Decreases were noted in intake of milk, vegetable and legumes, beef, pork, and eggs. Lower parental educational levels are associated with higher consumption of soft drinks and sweetened beverages. Additional trends include increase in eating out as well as expanded portion sizes in the US. Food eaten outside of the home is higher in both total and saturated fat on a percentage bases and contains less dietary fiber, calcium, and iron per calorie. Based on this information, eating away from home is associated with a compromised quality of nutritional intake and may increase risk for chronic diseases.

Snacking has also increased significantly among US children. It has been found that snacking, which accounts for a significant portion of total calories and macronutrients consumed, increased among all age groups.

Malnutrition and Food Insecurity

Malnutrition included undernutrition and over nutrition (excessive dietary intake of energy, fat, or cholesterol that predisposed individuals to chronic diseases). It is estimated that more than 13 million children in the United States are living below the poverty level and some estimates indicate that approximately 10% suffer from clinical malnutrition.

The term food security implies the ready availability of adequate and safe foods, whereas food insecurity is having “limited or uncertain availability of nutritionally adequate and safe foods or limited or uncertain ability to acquire acceptable foods in socially acceptable ways.” Food security status is categorized as: High food security, marginal food security, low food security, or very low food security. Prevalence of food insecurity was greater in metropolitan area, southern and southwestern states, poor households, household with children headed by a single woman, and African-American and Hispanic household. Research has linked food insecurity with increased developmental risk and poor health outcome.

Pediatric Undernutrition

Infants and young children whose weight curve has fallen 20% below the ideal weight for their height are described as failure to thrive. Iron and zinc are two micronutrients commonly found to be at marginal levels in youth with poor nutrition.
           
            Iron
·      Iron is a component of blood hemoglobin and muscle myoglobin and also functions as a cofactor for many enzymatic reactions in the body and is important to proper functioning of the immune system. Consequences of iron deficiency are anemia, poor cognition, and lower scholastic achievement. Prolonged bottle feeding for up to 48 months of age was positively correlated with the increased prevalence of iron deficiency. Iron deficiency was significantly higher in overweight toddlers. Association between overweight and iron deficiency include high-calorie, low-iron diets, altered iron metabolism, genetic influences, and physical inactivity, which would lead to decreased myoglobin breakdown and therefore decreased blood iron. Common oral manifestations are glossitis, angular cheilitis, and candidiasis.

Zinc
·      Zinc is important for proper growth and development, sexual maturation, immune function, and wound healing. Zinc deficiency may result from low dietary intakes, low bioavailability, or through disease processes. Oral manifestations include impaired wound healing, alterations of the oral epithelium, xerostomia, altered sense of taste, reduced appetite, and increased risk for dental caries and oral infections.

Calcium
·      Calcium is essential for proper nerve and muscle activity, blood clotting, transport of ions, and mineralization of the skeleton and dentition. Inadequate calcium intake over time can increase the risk of bone demineralization and osteoporosis. Childhood and adolescence are crucial times for development of the skeletal system and the dietary requirement for calcium peaks during the teenage years. The recommended intake of calcium is 1300 mg per day during adolescence, which equals the amount of calcium present in 4 1/3 cups of milk.

Vitamin D
·      Vitamin D is crucial for proper skeletal and dental development; it increases calcium absorption from the GI tract. Lack of the vitamin may result in hypertension, MS, cancer, and rickets in children. The presence of rickets during tooth development may result in enamel and dentin hypoplasia, incomplete development, or delayed eruption.

Vitamin B12
·      It’s essential for the synthesis of red blood cells and for myelin synthesis. It’s not present in plant foods, so patients following vegetarian diets should ensure an adequate intake of vitamin B12. Chronic Vit B12 deficiency results in pernicious anemia, oral soreness and atrophic glossitis.

Pediatric Overnutrition

·      In the US, malnutrition is more likely to be related to overconsumption of food rather than under-consumption. Eating habits in America are characterized as convenient, inexpensive, and largely portioned. Adherence to this type of eating pattern from childhood to adulthood contributes to obesity and to numerous diseases (ie. Diabetes, hypertension, coronary heart disease).

Eating Disorders

About 5 million Americans suffer from eating disorders; 5% of female and 1% of male Americans have anorexia nervosa, bulimia nervosa, or binge eating disorder.

·      Anorexia nervosa: Preoccupation with appearance and body weight during adolescence may lead to anorexia nervosa, which is self-induced starvation. It’s characterized by self-imposed weight loss, amenorrhea, and a distorted attitude toward eating and body weight. Nutritional deficiencies may lead to glossitis, gingivitis, a reduction in the amount and pH of the saliva, and an increase in dental caries susceptibility. Dental erosion may be evident on the palatal aspect of anterior and posterior teeth due to the use of sports drinks, caffeinated/carbonated drinks, wine, vinegar and lemon juice used to quell sensations of hunger.

·      Bulimia-Characterized by binge eating and self-induced vomiting. Because of the exposure of the tooth surfaces to the highly acidic regurgitated gastric contents, enamel erosion is common among bulimia nervosa patients.

Nutritional Considerations from Infancy Through Adolescence

Infant and Toddler

The period of most rapid growth in humans occurs during the first 6 months of life. Fats are the main dietary source of energy and essential fatty acids for infants and can account for up to 50% of the calories in breast milk. Breast-feeding continues to be the best overall method of infant feeding. There is no nutritional need for introducing solid foods before 6 months of age. Earlier use may contribute to the development of allergies or increased risk of obesity.

Preschooler

Physical growth occurs in spurts between 3 and 6 years of age. The child is not growing as rapidly as in the first year, thus fewer calories are required but high protein and mineral needs remain.

School-aged child

The 6 to 12 year stage is generally accompanied by a reduced rate of growth, which results in a decline in food requirements per unit of body weight. A focus on eating foods with high nutrient value and maintaining sufficient physical activity levels is important throughout this age range.

Adolescent

The nutritional requirements of adolescents are influenced primarily by the onset of puberty and the final growth spurt of childhood. The increase in growth rate is accompanied by increased needs for energy, protein, vitamins, and minerals.



Assessment of Article:  Level of Evidence/Comments: Level 1



Preventing dental caries through school-based sealant programs

Department of Pediatric Dentistry
Lutheran Medical Center

Resident’s Name: Nicholas Paquin                                                                             Date: 08/26/2015

Article Title:  Preventing dental caries through school-based sealant programs
Author(s): Gooch, et al.
Journal: JADA
Date: Revised November, 2009
Major Topic: School-based sealant programs
Type of Article: Systematic Literature Review
Main Purpose: Guidelines for clinicians in school-based sealant programs.
Key Points/Summary:
- In 2001, Community Preventive services completed a systematic review on school sealant programs. The median decrease in occlusal caries in posterior teeth among children aged 6-17 was 60%.
-Available data show that children aged 6-11 from families living below the federal poverty threshold ($21,800 annually for family of 4), are 2x as likely to have developed caries in their permanent teeth . Overall 90% of carious lesions are found in the pits and fissures of permanent posterior teeth.
-Only 20% of children 6-11 from low-income families has received sealants.  40% of children from families with income greater than 2x the poverty threshold, (Dye et al.)
-Large disparities according to race/ethnicity. Non-Hispanic African Americans 21%, Mexican Americans 24%, less likely to receive sealants than non-hispanic white children 36%, of low income families. (Dye et al)
-School sealant programs can be an important intervention to increase sealants on these children. The protocol is to have sealant programs at high-risk schools, those where 50% of more of the children are eligible for free or reduced-price meals. This eliminates discrimination.
Counterarguments:
-What if lesions are present but missed by not having radiographs?
-If follow-up is not guaranteed, will lost or partially lost sealants increase the risk of developing caries on those teeth?
-What surface cleaning methods are being used in the school based sealant program?
Key Findings
-Identifying lesions - Visual assessment lone is sufficient to detect the presence of surface cavitation and/or signs of dentinal caries, Ismail AI, et al and Pitts N, et al. 
-On sound pit and fissure surfaces – Llorda et al. found reduced caries by 78% @ 1yr, 59% @4+ yrs. Ahovuo-Salorants et al found 87% @ 1yr, 60% at 4+ yrs.
-On Non-cavitated/incipient lesions – consistent finding across 6 studies: reduced the percentage of lesions that progressed by 71% up to 5 years after placement in children adolescents and young adults. (non-cavitated lesions – no discontinuity or break in the enamel surface.)
-Reducing bacteria levels in cavitated carious lesions – Sealants lowered the number of viable bacteria, including strep. Mutans and lactobacilli, by at least 100 fold, and reduced the number of lesions with any viable bacteria by 50%.
-Surface preparation – Gray and colleagues reviewed instructions for use for 10 unfilled sealant products from five manufacturers and found that all directed to clean the tooth surface prior to acid etching. Non stated which cleaning method should be used. 5 mentioned the use of pumice slurry or prophylaxis paste and/or brush. The effect of specific surface cleaning or enamel preparation techniques on sealant retention cannot be determined at this time because small number of clinical studies comparing specific technique.
-Four handed technique – Use of 4 handed placement technique is associated with a 9% point increase for sealant retention, Griffen et al.
-Caries risk associated with lost sealants – Griffin et al completed a meta-analysis indicating that the caries risk for sealed teeth that have lost some or all of the sealant does not exceed the caries risk for never sealed teeth. Thus the potential risk associated with loss to follow-up for children in school-based programs does not outweigh the potential benefit of dental sealants.

-School based sealants are strongly recommended, for all the benefits mentioned above, and lack of any inherent harm from any counterarguments.
 

Oral Biofilms: Emerging Concepts in Microbial Ecology


Department of Pediatric Dentistry
Lutheran Medical Center

Resident’s Name:             Leslie M Slowikowski                                                                        Date: 08/25/2015
Article Title: Oral Biofilms: Emerging Concepts in Microbial Ecology
Author(s): S. Filache
Journal: Journal of Dental research
Date:  2010
Major Topic: Biofilm
Type of Article: Review articles
Main Purpose: Review microbial biofilm (collection and purpose)
Key Points/Summary: Human oral microbiome is comprised of hundreds of micro-organisms and is expected to rise into the thousands with the advances in mass sequencing techniques. 

Microbial Ecological Factors that affect oral biofilm development:  Inter-bacterial co-adhesion, pH, oxygen, and nutrients.  This is a dynamic process which leads to the establishment of micro-niches, metabolic functions, and inter- and intra-species interactions.  In 1991, Marsh proposed a new-widely-accepted idea that a change in the key environmental factor )or factors) will trigger a shift in the balance of the resident plaque microflora to a disease-associated species composition—the ecological plaque hypothesis. 

Ecology of dental plaque in health and disease:  There is ecological balance between the human host and indigenous micro-organisms.  Dental plaque bacteria are faced with challenges of a health compatible state – influenced by high-sugar content foods, tobacco smoke, aging process, genetic factors, immune changes, varying oral hygiene routines, socio-economic status and fluoridated water.   Most work is being completed on what causes disease but what is present in health is also important.  Over the past number of years we have accepted that dental caries and periodontal disease is multi-factorial and progressive.

Metagenomic analysis of the oral microbiome:  Sequencing has revealed new species but not without limitations.  PCR sequencing, and Pyrosequencing that relies on the detection of pyrophosphate (PPi) call tell use what kind of bacterial is present.  Cultivation techniques are having a come back due to this idea of environmental ecosystems.  Identification of species is good but dose not give information about function or metabolic requirements. 

Inter-Individual variation in the oral microbiome:  Despite high levels of genetic similarity, humans respond differently to different stimuli, biological stressors, and environments.  Therefore each individual microbiomes are as unique as a fingerprint and need to be studies as such.

Inter-individual variations in plaque develop and the progression of disease - The role of microbial aggregates: In the past plaque development has been generalized but now it is starting to be considered individualized as each person.  This new idea is convincing but is limited in research.  However microbial aggregates present in saliva could be related to the progression of oral disease.   A microbial aggregate is the capacity of oral bacterial to form inter-specific interactions that make adherence more likely.   

Biofilm detachment and dispersal – Role of Micorbial aggregates: Detachment is important in the dissemination of infection and contamination.  Three many ways: swarming dispersal, clumping dispersal and surface dispersal – all of which would have fluid phase and surface-associated phase.  These detachment theories could be a therapeutic target in the management of plaque-induced disease and may limit the proliferation of oral biofilm development. 

Development of Heterogeneous plaques – The roles of location and spatial patterning: Microbial diversity is spatially structured by geographic location as well as by the environment.  Site-specificity could be linked to a series of competitive interaction between certain oral bacteria.  Determining community structure in relation to geographical location on the teeth with in the oral cavity is important. 

Implications for the treatment of oral diseases – an ecological approach:  Current model is based mechanical/chemical removal of plaques.  The inherent problem with this, especially with chemotherapeutics, is a sub-population of bacteria could remain viable and able to proliferate possibly becoming more pathogenic then the original bacteria present.

Inter-individual variation and treatment responses:  Challenges lie in what is normal for that particular individual.  Studies suggest that different bacteria may be responsible for disease in different people, which suggest that disease progression is person-specific.  In addition to growth environment  - host specificity, bacterial strain variation, bacterial species arrangement in plaque all contribute to the outcome of chemotherapeutic treatment. 

Biofilm structure, Altruistic behavior, and antimicrobial treatment: Biofilm structure influence the penetration of antimicrobials, limiting their effectiveness.  Also some bacteria can confer protections on another at its own expense, which can help the biofilm survive overall.

New-generation therapeutics:  Exploring the idea of interruption horizontal gen transfer in E. coli to prevent antibiotic drug resistance.  Anther approach is optimizing the action of antimicrobial peptides. 
Assessment of Article:  Level of Evidence/Comments: III