Dental Filling

What is a dental filling?

A dental filling is a plug to seal the hole or cavity in your tooth. The filling helps to reduce the sensitivity to hot and cold, relieve pain from the cavity, keeps the food and bacteria away from the hole. 

Dental Filling Materials

Composites Dental Filling

  • Made of plastic
  • Mimics the tooth colour
  • The most common white filling used
  • Good to seal small to medium size cavities
  • This material bonds to enamel only. If no enamel is present white filling should not be used, as the bond will break down within 6 to 12 months
  • Good to repair only small chips in the front teeth if the bite is light
  • Should not be used if the bite is heavy or the chip is large
  • Moderate stain resistance
  • Cannot reinforce and make the tooth stronger
  • Moderate cost due to the time required to do the filling
  • Composite shrinks as it sets, causing the walls of the tooth to flex

Silver Dental Filling

  • Made of elements from mercury, silver, tin and copper
  • Some mercury might be released from the filling with excessive chewing
  • FDA does not recommend amalgam filling for high-risk individuals (i.e. pregnant women)
  • Lasts longer than composite fillings
  • If it expands it can cause a fracture in the tooth requiring a crown or a complete extraction
  • The tooth becomes darker over time due to the breakdown of the filling
  • Lower cost

Ceramic Dental Filling

  • Matches natural tooth color
  • Stronger than composite
  • Prolongs the appointment time
  • Better seal than composite
  • No shrinkage when setting
  • Higher cost

Gold Dental Filling

  • Durable – can last 20+ years
  • Strongest of all the filling
  • Gold or Silver looking
  • Requires very precise work by the dentist
  • Very good seal
  • Two appointments procedure.
  • Higher cost

Why do you need a filling?

If you have a hole in your tooth, it is most likely from a cavity. It is best to do the filling to seal the tooth to minimize the damage to the tooth. 

Risk Factors for Tooth Cavity

The tooth with a cavity needs to be sealed. There are many risk factors for cavities. Genetics is probably the most important factor. Genetics controls the density of the tooth structure. The tooth structure is divided into the crown and the root. The crown part of the tooth structure has enamel and the root part has dentine. Enamel is dense and strong, dentine is less dense and much weaker. Enamel and dentine vary between individuals. The hardness of some enamel feels like maple hardwood while others feel like styrofoam. 

Both enamel and dentine are highly affected by the acidity of the mouth. The mouth through the saliva tries to maintain a neutral pH of 7. Diet plays a significant role in the development of cavities with most food groups in the pH range of 3-4. The pH difference of 1x is actually in the magnitude of 10x. 

It is better to fill the cavity even if you are not experiencing pain. The cavity in time will get deeper and bigger and if unattended will need a root canal.  

The other hole in the tooth could be from acid erosion(link erosion) and toothbrush abrasion.

How do you do a filling?

A filling may take 15 mins to over an hour to do depending on the size of the cavity. To control pain during the procedure, a topical and local anesthetic is given. Once the anesthetic is working, you should feel no or minimal pain, unless you have a “hot tooth’’, intense pain upon lightly touching, constant pain. The tooth is isolated by a rubber dam. The cavity is removed and cleaned with the dental handpiece using cold water spray to prevent overheating the tooth. The prepared tooth is disinfected and filling is placed. The types of filling vary according to design and material. Once the filling is placed, the bite is checked with very thin marking paper and the filling is adjusted accordingly to the existing bite. If you have to replace the filling, the process is the same. 

How does a filling impact your health?

Once a cavity exists the tooth becomes weaker. Small fillings do not significantly affect the strength of the tooth, however, with larger fillings, the tooth needs to be reinforced with a crown to protect the tooth. The tooth may still be sensitive to hot and cold after the filling is done. The sensitivity is dependent upon the depth of the cavity, the deeper the cavity, it is closer to the nerve and tends to be more sensitive. In some instances, a root canal may be necessary.

After the filling is done, it is important to be careful while the anesthetic is there, not to bite on your cheek, tongue without realizing it. Once the local anesthetic is worn off, the bite may feel a bit strange for a very short period up to a few hours. If the bite feels different for more than 24 hours, then you may have the dentist adjust your filling. If the bite feels off after a few days and adjustment and the tooth is still sensitive, then the tooth may need a root canal.

What is the cost of dental filling?

The cost of filling depends on the size of the cavity, it can vary from USD $90 to $300. The cost goes up as more surfaces are involved. 

Terminology on the tooth surface to determine the cost. Each tooth is made up of a total of 5 surfaces, O=occlusal, M=Mesial, D=Distal, B=Buccal, L=Lingual.  The one surface filling will cost the least and the five surface filling will cost the most.  

How long does the filling last? 

Generally, a filling can last up to 5-7 years. The more important question should be what does my tooth look like at the end of 5-7 years. Keep in mind you can always replace filling but not your tooth.

How long the filling lasts is dependent on the following.

  1. Chewing force: The range of chewing force varies from 25 lbs to 300 in the same person. Generally, the back teeth experience heavier force than the front teeth.   
  2. Diet: The acid in the diet weakens the border between the filling and the tooth structure, acid may also attack and breakdown the filling and the tooth. 
  3. Bacteria on the surface of the filling and the tooth: Rough surface gathers plague, bacteria in the plaque produces an acid that causes the breakdown.   
  4. Temperature changes in the mouth with hot and cold: The cyclic changes in the hot and cold causes expansion and contraction of the filling and the tooth. Breakdown happens because no filling material can match exactly the same amount of changes in the tooth.
  5. Saliva and enzymes that break the filling down: Hydrolytic or breakdown by water as water is absorbed by the filling especially composite.       
  6. Grinding or obstructive sleep apnea with breathing problems: Due to difficulties in breathing through the nose during sleep, the mouth has to move to provide breathing. In the process of moving the mouth, the teeth may be in the way of the movement, teeth and or filling may break.   
  7. Nail-biting: Nail-biting produces heavy pressure on the tooth.

What can you do to make your filling last longer?

  1. Regular brushing and flossing.
  2. Avoid biting nails, pencil.
  3. Avoid putting objects in your mouth unless for eating.
  4. Consume less acidic food
  5. Use fluoride too paste
  6. Use alkaline toothpaste and mouth rinse

What can your dentist do to make your filling last longer?

  1. Proper cavity removal
  2. Proper smooth finishes
  3. Correct in between teeth finishes if in between is involved
  4. Proper time for the LED light to activate the composite to make it set more thoroughly
  5. Check the bite thoroughly using marking paper

Dr. David Cheng

A practicing dentist with over 30 years of experience and more than 3500 hours of continuing studies. He lives in both Toronto, Canada and Seattle, WA. Besides writing for this website, he practices dentistry in different clinics in Canada and mentors other dentists in the USA and Canada.

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