Either braces, a dental implant or a bridge. The cheapest is a bridge. Do NOT allow your teeth to shift. More problems will occur. Find a reputable dentist to get an honest opinion. Braces and dental implant costs around $5,000.00 and a bridge from $800-$1200. Some orthodontists will brace a couple of teeth to keep that side from shifting. But most refuse to do it. Call around. The really decent ones love to help and answer questions.