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                                                                     EXHIBIT 8.1


               [LETTERHEAD OF WALLER LANSDEN DORTCH & DAVIS, PLLC]





                                 August 6, 2001


Orthodontic Centers of America, Inc.
3850 N. Causeway Boulevard, Suite 1040
Metairie, Louisiana 70002

Ladies and Gentlemen:

         We have acted as special counsel to Orthodontic Centers of America,
Inc., a Delaware corporation ("OCA"), in connection with (i) the proposed merger
(the "Merger") of OCA Acquisition Corporation, a Delaware corporation ("OCA
Merger Sub") and a wholly-owned subsidiary of OCA, with and into OrthAlliance,
Inc., a Delaware corporation ("OrthAlliance"), pursuant to the terms of the
Agreement and Plan of Merger, dated as of May 16, 2001, by and among OCA, OCA
Merger Sub and OrthAlliance (the "Merger Agreement") and (ii) the preparation
and filing of the Registration Statement on Form S-4 (the "Registration
Statement") with the Securities and Exchange Commission (the "Commission") under
the Securities Act of 1933, as amended (the "Securities Act"), which includes
the Proxy Statement/Prospectus of OrthAlliance and OCA (the "Proxy
Statement/Prospectus"). This opinion is provided pursuant to the requirements of
Item 601(b)(8) of Regulation S-K under the Securities Act.

                             INFORMATION RELIED UPON

         In rendering the opinion set forth herein, and with your consent, we
have examined and relied upon originals or copies, certified or otherwise
identified to our satisfaction, of the Merger Agreement, the Registration
Statement, the Proxy Statement/Prospectus, and the representations (which we
have neither investigated nor verified) given to us by certificate, dated August
2, 2001 by officers of OCA and OCA Merger Sub and by certificate, dated August
2, 2001 by an officer of OrthAlliance (collectively, the "Certificates"). In
addition, we have examined such other documents, agreements, and certificates
and made such investigations of law and fact as we have deemed necessary or
appropriate as a basis for the opinion set forth below.

         In our examination, we have assumed, with your consent, the genuineness
of all signatures, the legal capacity of natural persons, the authenticity of
all documents submitted to us as originals, the conformity to original documents
of all documents submitted to us as certified or photocopies and the
authenticity of the originals of such copies. As to any facts material to this
opinion which we did not independently establish or verify, we have relied upon
the accuracy and completeness of (i) the statements and representations made by
OCA, OCA Merger Sub and OrthAlliance and (ii) the Proxy Statement/Prospectus,
and we have assumed that such will be complete and accurate through the date
hereof and will continue to remain complete and accurate as of the Effective
Time. In addition, we have assumed, with your consent, that the statements
contained in the Certificates are complete and accurate on the date hereof and
will be complete and accurate as of the Effective Time, and that any
representation made in any of the documents referred to herein "to the best of
the knowledge and belief" (or similar qualification) of any person or party is
now and will be as of the Effective Time complete and accurate without such
qualification. We have also assumed that the transactions contemplated by the
Merger Agreement will be consummated in accordance therewith and as described in
the Proxy Statement/Prospectus and that the Merger will qualify as a statutory
merger under the applicable laws of the State of Delaware.

         Unless specified, capitalized terms used herein shall have the meanings
assigned to them in the Proxy Statement/Prospectus or the appendices thereto
(including the Merger Agreement). All references herein to the "Code" are to the
Internal Revenue Code of 1986, as amended.


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                                     OPINION

         On the basis of the foregoing, and subject to the assumptions,
qualifications and limitations stated herein, we are of the opinion that:

         (i) The Merger will be treated for federal income tax purposes as a
reorganization within the meaning of Section 368(a) of the Code; and

         (ii) OCA, OCA Merger Sub and OrthAlliance will each be a party to the
reorganization within the meaning of Section 368(b) of the Code.

         The opinion expressed herein is based upon existing statutory,
regulatory and judicial authority, any of which may be changed at any time with
retroactive effect. There can be no assurances that the opinion expressed herein
will be accepted by the Internal Revenue Service or, if challenged, by a court.
In addition, our opinion is based upon the documents that we have examined, the
additional information that we have obtained, and the facts set out in the
Certificates that we have assumed, with your consent, to be true and correct.
Our opinion cannot be relied upon if any of the facts contained in such
documents or in any such additional information is, or later becomes,
inaccurate, or if any of the facts set out in the Certificates is, or later
becomes, inaccurate. Our opinion is limited to the United States federal income
tax matters specifically covered thereby, and we have not been asked to address,
nor have we addressed, any other tax consequences that may result from the
Merger or any other transaction (including any transaction undertaken in
connection with the Merger).

         This letter is furnished to you for use in connection with the Merger,
as described in the Merger Agreement and the Proxy Statement/Prospectus, and is
not to be used, circulated, quoted, or otherwise referred to for any other
purpose without our express written permission. We hereby consent to the filing
of this opinion with the Commission as an exhibit to the Registration Statement,
and to the reference to our firm under the heading "THE MERGER-Certain Federal
Income Tax Consequences" in the Proxy Statement/Prospectus. In giving such
consent, we do not thereby admit that we are in the category of persons whose
consent is required under Section 7 of the Securities Act or the rules and
regulations of the Commission thereunder.


                                         Very truly yours,


                                         /s/ WALLER LANSDEN DORTCH & DAVIS, PLLC



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