Bite issues (underbite, overbite, crossbite) are caused by problems with teeth alignment. This may be due to
Overcrowding
Tooth size proportion discrepancy: The combined size of the upper teeth may not be proportional with the combined size of the lower teeth.
Jaw size proportion discrepancy: The roots of the teeth are anchored in the jawbone, so when the upper and lower jaw size is not proportional, the position and how the upper and lower teeth fit together will also be affected.
There are 2 ways to correct an underbite:
Orthodontics: braces are used to move teeth around into the proper alignment without doing an irreversible procedure (drilling into the teeth).
Prosthodontics: placing artificial coverings (veneers or crowns) to realign the teeth. This is beneficial when the teeth are also worn or discoloured as the artificial materials can reshape and recolour the teeth.
There are several benefits from choosing orthodontic correction before/instead of prosthodontic correction:
Better space management: If there is overcrowding, ideal tooth shape and proportions cannot be achieved. This results in odd-looking crowns/veneers.
Better root positioning: Tipping the crown of the tooth forward to "jump" an underbite (in the upper arch) will cause the tooth to be loaded (bitten on) off-centre. This can cause fremitus (excessive tooth movement), loosening or tooth migration over time. Moving the tooth orthodontically ensures that both the root and the crown of the tooth are in harmony.
In patients with gum disease (periodontitis), excessive tipping force may cause the progression of bone loss.Better gum volume: Moving the tooth to the appropriate position ensures that the crown of the tooth is in harmony with the gum. Merely crowning an instanding (where a tooth is tipped or positioned inward) tooth to bulk it out labially (forward) tends to create an overhang at the gumline and an unattractive shadow.
Increased tooth trimming: If a tooth is protruding, then crowning it to realign it will often require more aggressive drilling to provide sufficient material bulk for aesthetics and to reposition the crown of the tooth. If teeth are overcrowded, reshaping of the opposing teeth is also required to ensure that bite pressure is distributed evenly when the jaw moves.
