Chapter 17 – Dental Calculus (Hard Deposits) Study Notes

What You'll Learn

• What the acquired pellicle is and its role in keeping your mouth healthy.

• How dental plaque (biofilm) forms step-by-step and how the types of germs in it change as it grows.

• The difference between soft and hard deposits inside your mouth.

• What influences how much and how fast plaque and hardened plaque (calculus) build up.

• Where calculus and plaque are found, what they're made of, and their physical and chemical traits.

• How calculus sticks to your teeth, both above and below the gumline.

• How dentists find calculus using examinations and X-rays.

• How to teach patients about what causes plaque and calculus, how to prevent them, and how to create personal cleaning plans.

• The biological process of how calculus hardens and how long it takes.

• The role of plaque in causing cavities and gum (periodontal) disease.

What is Dental Calculus?

• It's essentially hardened dental plaque (biofilm). This happens when tiny crystals of calcium and phosphate minerals, found in your saliva, build up within the sticky germ-filled layer on your teeth.

• Importantly, calculus is always covered by a fresh, active layer of plaque. This unhardened plaque is what actually causes problems like gum disease, making calculus a continuous source of irritation.

Where Calculus is Commonly Found

Calculus Above the Gumline (Supragingival Calculus)

• Found on the tooth surface that is visible, above the gumline.

• Often builds up in specific spots:

  • On the inside surfaces of your lower front teeth.

  • On the outside surfaces of your upper first and second molars (back teeth).

  • On teeth that are crooked or out of alignment.

  • On teeth you don't use much for chewing, or those you miss when brushing.

  • On dental work like removable dentures, fixed bridges, implants, and even oral piercings.

• Its spread can be affected by things like:

  • Unilateral hypofunction: Only chewing on one side of your mouth.

  • Salivary duct proximity: Being close to where saliva exits into your mouth.

  • Your individual habits.

Calculus Below the Gumline (Subgingival Calculus)

• Found below the gumline, extending down the root surface of teeth and implants.

• Its distribution can be described as:

  • Generalized: Found on $\ge 30\%$ of your teeth.

  • Localized: Found on $\lt 30\%$ of your teeth, or only on one tooth or a few specific teeth.

• It's usually thinnest on the front surfaces of teeth and thickest in between teeth or in hard-to-reach spots.

• Its color gets darker (from light brown to black) because it's exposed to fluids from the gums (gingival crevicular fluid or GCF) and blood pigments.

• The CEJ (Cementoenamel Junction), which is where the enamel of the tooth crown meets the cementum of the root, often becomes a common spot where calculus forms as gums recede and gum pockets get deeper.

What Calculus is Made Of

Non-Living Stuff (Inorganic Fraction) - The Main Part

• Elements: Mostly made of calcium (Ca), phosphorus (P), carbonate ($CO_3$), sodium (Na), and magnesium (Mg).

• Tiny amounts of other elements: Such as copper (Cu), zinc (Zn), strontium (Sr), manganese (Mn), silicon (Si), fluoride (F), iron (Fe), and potassium (K).

• Four main types of calcium-phosphate crystals: These are the building blocks of calculus.

  • Brushite: Common in new calculus deposits.

  • Octacalcium phosphate: Found on the outer layers of calculus above the gumline.

  • Hydroxyapatite: The most common crystal in older dental calculus.

  • Whitlockite: Most common in calculus found below the gumline.

• Fluoride source: Calculus can absorb fluoride from things you use, like fluoridated water, fluoride treatments at the dentist, and toothpaste.

• How much inorganic material is in teeth vs. calculus:

  • Enamel (outer layer of tooth crown): $95\text{–}97\%$ inorganic.

  • Dentin (layer under enamel): $45\%$ inorganic.

  • Cementum / bone (root surface and jaw bone): $45\text{–}70\%$ inorganic.

  • Calculus above the gumline: Averages $37\%$ inorganic (can be up to $80\%$).

  • Calculus below the gumline: Averages $58\%$ inorganic (can be $60\text{–}80\%$).

Living & Other Stuff (Organic Matrix)

• Cells and cell parts:

  • Living and dead bacteria.

  • Shed skin cells from inside your mouth.

  • White blood cells.

  • Salivary mucin (glycoprotein): A sticky protein found in saliva that helps calculus stick.

• Chemical substances:

  • Lipids (fats like free fatty acids and phospholipids).

  • Proteins from saliva, blood serum, and bacteria.

• These organic parts act like food storage for germs, can trigger your immune system, and give the calculus its structure.

What Makes Calculus Form Faster?

• Salivary supersaturation with Ca & P: When your saliva has an extra high amount of calcium and phosphorus, which are the minerals that form calculus. People who form a lot of calculus can have up to 3 times more phosphorus in their saliva than light calculus formers.

• The pH (acidity/alkalinity), buffering capacity (ability to resist pH changes), and flow rate of your saliva and gum fluid (GCF).

• How well you clean your teeth, your diet, whether you use tobacco, certain health conditions, and medications.

How Calculus Forms and How Long It Takes

1. Starts with a sticky layer: It begins as regular, unhardened plaque (biofilm).

2. Minerals arrive: Your saliva and gum fluid provide the calcium and phosphorus ions needed.

3. Dead germs act as starting points: The walls of dead bacterial cells provide rough surfaces for mineral crystals to start forming.

4. Crystals grow: Fats (phospholipids) in the biofilm help bind calcium and phosphate together, forming crystal layers.

   • The very first crystal to form is brushite.

   • Over time, these crystals mature and change: brushite transforms into octacalcium phosphate, then whitlockite, and finally hydroxyapatite.

5. Quick hardening: About half of the total mineral content of calculus forms within the first 2 days if you don't brush well.

6. Full hardening: On average, it takes about $12$ days for soft plaque to become fully hardened calculus (though it can range from 10 to 20 days).

7. Stable phase: The calculus reaches its most stable form around $8$ months, though crystal growth continues slowly.

Types and Characteristics of Calculus (How it Looks and Feels)

Above the Gumline (Supragingival)

• Color: Can be white, creamy-yellow, or gray. It might also have stains from tobacco or food.

• Shape: Often looks like irregular, bulky chunks that take the shape of your teeth and are influenced by your lips and tongue.

• Consistency: Newer deposits are less dense and not as hard (only about $37\%$ mineralized).

• Size/Quantity: How much you have is affected by your oral hygiene, diet, saliva flow, and tobacco use.

Below the Gumline (Subgingival)

• Color: Ranges from light brown to dark brown/green to black, due to absorbing pigments from gum fluid (GCF).

• Shapes: Can appear as:

  • Crusty spicules: Tiny, rough bits.

  • Ledges/rings: Bands or shelves around the tooth.

  • Thin veneers: Very thin, flat layers.

  • Finger-/fern-like projections: Branching shapes.

  • Isolated islands: Small, separate pieces.

• Consistency: Even the newest deposits at the bottom of a gum pocket are quite dense (around $58\%$ mineralized), making them harder than calculus found above the gumline.

• Size/Quantity: Factors include your oral hygiene, age, amount of bacteria present, and how severe your gum disease is.

How Calculus Sticks and How Hard It Is to Remove

1. Sticking to the Acquired Pellicle:

   • This is the very first way calculus attaches. The acquired pellicle is a thin, clear, sticky film that naturally forms on your teeth moments after you clean them. Calculus that attaches here is the easiest to remove because it's not locked into the tooth surface.

2. Sticking to Tiny Rough Spots:

   • Calculus can get stuck in small defects on the tooth's root or enamel. These include cracks, pits from resorption (where tooth structure has been lost), tiny holes where fibers used to attach (Sharpey's fiber pores), cavities, or even grooves accidentally made during previous cleaning processes.

   • This creates a mechanical locking effect, making it very difficult and time-consuming for your dental professional to remove.

3. Direct Contact (Crystals Fusing):

   • In this strong attachment, the calcium-phosphate crystals in your tooth's enamel or root (hydroxyapatite) directly fuse with the crystals in the calculus itself.

   • This bond is very strong but can be brittle. During cleaning, the bulk of the calculus might break off, but tiny microscopic crystal pieces can remain stuck to the tooth surface.

Why Calculus Matters in Gum Disease

• Calculus is considered a secondary factor in gum disease. It doesn't start the disease, but it creates a perfect environment for bad bacteria to thrive.

• It acts like a shelter, protecting the disease-causing plaque (biofilm). This plaque then releases harmful toxins that trigger your body's immune system, leading to inflammation.

• Calculus helps the plaque move further down the tooth root, which leads to deeper gum pockets and loss of the tissue that holds your tooth in place.

• Important takeaway: Studies show that gums can heal even if tiny bits of calculus remain, as long as the harmful plaque is consistently removed and disrupted. This means controlling the daily plaque is more important than simply eliminating every single piece of calculus.

How Dentists Find Calculus

Above the Gumline (Supragingival)

• Direct/indirect vision: Looking directly in your mouth or using a dental mirror.

• Using compressed air to dry the teeth, which makes the chalky, white calculus more visible.

• Tactile exploration: Feeling for rough spots with a dental instrument.

Below the Gumline (Subgingival)

• Color change: Looking for changes in the color of the gum tissue near the tooth.

• Air deflection: Using a puff of air to see if the gum tissue moves away from the tooth due to calculus underneath.

• Tactile detection: Feeling for rough areas on the root surface with a special dental explorer tool.

• Endoscopy: Using a tiny camera (endoscope) for finding calculus that's smooth (burnished) or very thin (veneer calculus).

• Bitewing radiographs: X-rays can sometimes show large calculus ledges between teeth.

How Gum Tissue Responds

• Comparing photos of inflamed gums before cleaning to healthy, firm gums after a deep cleaning clearly shows the benefits of removing calculus and plaque.

Preventing and Managing Calculus

• Your Personal Cleaning Routine:

  • Learning and using the best tooth-brushing method for you.

  • Using tools to clean between your teeth, like floss, interdental brushes, or water flossers.

  • Choosing the right toothpaste, especially those with ingredients that fight calculus (anticalculus formulations).

  • Getting regular education on how to clean your mouth, demonstrations, and reminders at every dental visit.

  • Getting advice on your diet to limit sugary foods (which cause cavities) and encourage foods that help strengthen tooth enamel.

• Professional Dental Care:

  • Regular cleanings (prophylaxis) or specialized gum therapy (supportive periodontal therapy) to keep calculus levels low, both above and below the gums.

  • Regularly checking to see how effective your home cleaning is and assessing your risk for calculus buildup.

• Toothpastes with Calculus-Fighting Ingredients:

  • Toothpastes containing ingredients like zinc citrate or pyrophosphates are used.

  • These ingredients stop new calculus from forming on visible tooth surfaces; they do NOT dissolve calculus that has already hardened.

Key Points for Patient Education

• Clearly explain where plaque/calculus are found, what they're made of, and how they contribute to disease.

• Show how thorough daily cleaning prevents plaque from hardening into calculus.

• Point out sugary and starchy foods that lead to cavities.

• Explain the step-by-step process of calculus formation so patients understand why daily cleaning is so important.

What Dental Professionals Need to Record

• Write down how the deposits look: their color, texture, amount (slight/moderate/heavy), and where they are found.

• Note the exact tooth surfaces and sections of the mouth for future reference and for teaching the patient.

• Describe any stains (what kind, how much, where).

• Document the oral hygiene instructions (OHI) given: what techniques were shown, what products were recommended, and when the next check-up is scheduled.

• A sample form is provided in textbook Box 17-2.

Examples of Numbers and Measurements

• Average non-living content of calculus above the gumline: $\text{Inorganic} \approx 37\%$ (can go up to $\le 80\%$).

• Time for plaque to harden: $\text{Soft deposit} \xrightarrow{\approx 12\,\text{days}} \text{Mature calculus}$.

• People who form a lot of calculus have about $3 \times$ more phosphorus in their saliva compared to those who form less calculus.