EX-4

DESCRIPTION OF THE REGISTRANT’S SECURITIES REGISTERED
PURSUANT TO SECTION 12 OF THE SECURITIES EXCHANGE ACT OF 1934

BIOLASE, Inc. (“BIOLASE,” “we,” “us” or “our”) has one class of securities registered under Section 12 of the Securities Exchange Act of 1934, as amended, namely our common stock, par value $0.001 per share. This summary does not purport to be complete and is subject to the applicable provisions of the General Corporation Law of the State of Delaware (the “DGCL”), as well as our Restated Certificate of Incorporation, as amended (our “Charter”), and our Eighth Amended and Restated Bylaws (our “Bylaws”), each of which is included as an exhibit to our Annual Report on Form 10-K and incorporated by reference herein.

Under our Charter, we are authorized to issue 180,000,000 shares of our Common Stock and 1,000,000 shares of preferred stock, par value $0.001 per share.

Voting Rights. Holders of our Common Stock are entitled to one vote per share. Each of our directors is elected by the affirmative vote of a majority of the votes cast with respect to such director in uncontested elections. In a contested election, each of our directors is elected by an affirmative vote of a plurality of the votes cast by the shares represented and entitled to vote with respect to the election of such director. A “contested election” is defined in our Bylaws as an election with respect to which, as of the record date for the meeting at which directors are to be elected, the number of nominees exceeds the number of directors to be elected at such meeting. Vacancies on the BIOLASE board of directors (our “Board”) may be filled by an affirmative vote of two-thirds of the remaining members of our Board or at a meeting of the stockholders in the manner set forth in the second preceding sentence.

Dividend Rights. Subject to any preferential rights of any outstanding shares of our preferred stock to receive dividends before any dividends may be paid on our Common Stock, the holders of our Common Stock will be entitled to share ratably in any dividends that may be declared by our Board out of funds legally available for the payment of dividends. Our ability to pay dividends on our Common Stock will be limited by restrictions on our ability to pay dividends or make distributions to our stockholders and on the ability of our subsidiaries to pay dividends or make distributions to us, in each case, under the terms of our current, and any future, agreements governing our indebtedness.

Other Rights. Each holder of our Common Stock is subject to, and may be adversely affected by, the rights of the holders of any series of preferred stock that our Board may designate and we may issue in the future. Holders of our Common Stock have no preemptive, conversion or other rights to subscribe for additional shares. Our Common Stock does not carry any redemption rights or any preemptive rights enabling a holder to subscribe for, or receive shares of, any class of our Common Stock or any other securities convertible into shares of any class of our Common Stock.

Liquidation Rights. Subject to any preferential rights of any outstanding shares of our preferred stock, in the event of our liquidation, dissolution or winding up, holders of our Common Stock are entitled to share ratably in the assets remaining after payment of liabilities and the liquidation preferences of any outstanding preferred stock.

Standstill Agreements. Pursuant to (1) a standstill agreement with Jack W. Schuler, Renate Schuler and the Schuler Family Foundation (collectively, the “Schuler Parties”), dated November 10, 2015 (as amended on August 1, 2016 and November 9, 2017, the “Schuler Standstill Agreement”), and (2) a standstill agreement with Larry N. Feinberg, Oracle Partners, L.P., Oracle Institutional Partners, L.P., Oracle Ten Fund Master, L.P., Oracle Associates, LLC and Oracle Investment Management, Inc. (collectively, the “Oracle Parties”) dated November 10, 2015 (as amended on August 1, 2016 and November 9, 2017, the “Oracle Standstill Agreement” and, together with the Schuler Standstill Agreement, the “Standstill Agreements”), each of the Schuler Parties and the Oracle Parties agreed with respect to itself and its associates and affiliates (i) not to purchase or acquire any shares of our Common

Stock if such a purchase would result in aggregate beneficial ownership by it and its affiliates and associates in excess of 41% of the issued and outstanding shares of our Common Stock and (ii) not to sell, transfer or otherwise convey shares of our Common Stock (or warrants or other rights to acquire shares of our Common Stock) to anyone who will immediately thereafter beneficially own shares in excess of 20% of the issued and outstanding shares of our Common Stock, as a result of such transfer and other transfers from third parties.

Our Charter authorizes our Board to provide for the issuance of shares of preferred stock in one or more series without further authorization from stockholders. Prior to issuance of shares of each series, our Board is required by the DGCL and our Charter to fix the designation, powers, preferences and rights of the shares of such series and the qualifications, limitations or restrictions thereof.

We are subject to Section 203 of the DGCL (“Section 203”). In general, Section 203 prohibits a publicly held Delaware corporation from engaging in “business combination” transactions with any “interested stockholder” for a period of three years following the time that the stockholder became an interested stockholder, unless:

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prior to the time the stockholder became an interested stockholder, either the applicable business combination or the transaction which resulted in the stockholder becoming an interested stockholder is approved by the corporation’s board of directors;

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upon consummation of the transaction which resulted in the stockholder becoming an interested stockholder, the interested stockholder owned at least 85% of the voting stock of the corporation outstanding at the time the transaction commenced, excluding for purposes of determining the voting stock outstanding (but not the voting stock owned by the interested stockholder) shares owned by directors who are also officers of the corporation and shares owned by employee stock plans in which the employee participants do not have the right to determine confidentially whether shares held subject to the plan will be tendered in a tender or exchange offer; or

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at or subsequent to the time that the stockholder became an interested stockholder, the business combination is approved by the corporation’s board of directors and authorized at an annual or special meeting of stockholders by the affirmative vote of at least 66 2/3% of the outstanding voting stock which is not owned by the interested stockholder.

A “business combination” is defined to include, in general and subject to exceptions, a merger of the corporation with the interested stockholder; a sale of 10% or more of the market value of the corporation’s consolidated assets to the interested stockholder; certain transactions that result in the issuance of the corporation’s stock to the interested stockholder; a transaction that has the effect of increasing the proportionate share of the corporation’s stock owned by the interested stockholder; and any receipt by the interested stockholder of loans, guarantees or other financial benefits provided by the corporation. An “interested stockholder” is defined to include, in general and subject to exceptions, a person that (1) owns 15% or more of the outstanding voting stock of the corporation or (2) is an “affiliate” or “associate” (as defined in Section 203) of the corporation and was the owner of 15% or more of the corporation’s outstanding voting stock at any time within the prior three year period.

A Delaware corporation may opt out of Section 203 with an express provision in its original certificate of incorporation or by an amendment to its certificate of incorporation or bylaws expressly electing not to be governed by Section 203 and approved by a majority of its outstanding voting shares. We have not opted out of Section 203. As a result, Section 203 could delay, deter or prevent a merger, change of control or other takeover of BIOLASE that our stockholders might consider to be in their best interests, including transactions that might result in a premium being paid over the market price of our Common Stock, and may also limit the price that investors are willing to pay in the future for our Common Stock.

The ability to authorize undesignated preferred stock makes it possible for our Board to issue one or more series of preferred stock with voting or other rights or preferences. Thus, our Board could authorize the issuance of shares of preferred stock that have priority over our Common Stock with respect to dividends or rights upon liquidation or with terms and conditions that could have the effect of delaying, deferring or preventing a transaction or a change of control of BIOLASE that might involve a premium price for holders of our Common Stock or otherwise be in their best interests.

Our Bylaws establish advance notice procedures with respect to stockholder proposals and the nomination of candidates for election as directors, other than nominations made by or at the direction of our Board or a committee of our Board.

Our stockholders may take action by written consent in lieu of a meeting as provided in our Bylaws. Our Bylaws provide that certain procedures, including notifying our Board and awaiting a record date, must be followed for stockholders to act by written consent. A special meeting of our stockholders may be called only by our Board, the Chairman of the Board, the Executive Vice Chairman, the Chief Executive Officer or the President. A special meeting may also be called at the request of stockholders holding a majority of the aggregate number of shares of capital stock of BIOLASE issued and outstanding and entitled to vote at that meeting (subject to certain timeliness and content requirements of the demand).

Our Charter may be amended by the affirmative vote of a majority of the aggregate number of shares of each class of our capital stock issued and outstanding after a resolution of our Board declaring the advisability of such amendment has been adopted in accordance with Delaware law. Our Bylaws may be amended by the affirmative vote of a majority of the aggregate number of shares of each class of our capital stock issued and outstanding (and entitled to vote on the subject matter) present in person or represented by proxy at a meeting of stockholders provided that notice thereof is stated in the written notice of the meeting. Our bylaws may also be amended by a majority of our Board in accordance with Delaware law and our Charter, except that certain sections of our Bylaws (including but not limited to certain provisions regarding special meetings, voting, officers and approval of securities issuances) require either the affirmative vote of two-thirds of the persons then serving as directors on our Board or our stockholders.

Unless our Board acting on behalf of BIOLASE selects an alternative forum, the Court of Chancery of the State of Delaware (or, if the Court of Chancery does not have jurisdiction, another state court located within the State of Delaware or, if no court located within the State of Delaware has jurisdiction, the federal district court for the District of Delaware) shall be the sole and exclusive forum for (i) any derivative action or proceeding brought on behalf of BIOLASE, (ii) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees to BIOLASE or our stockholders, (iii) any action asserting a claim against BIOLASE or any of our directors, officers or other employees arising pursuant to any provision of the DGCL, our Charter or our Bylaws, (iv) any action asserting a claim against BIOLASE or any of our directors, officers or other employees arising pursuant to any provision of the DGCL, our Charter or our Bylaws or (v) any action asserting a claim against BIOLASE or any of its directors, officers or other employees governed by the internal affairs doctrine of the State of Delaware.

Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock is deemed to have notice of and consented to the above-described forum selection provisions.

Our Common Stock is listed on The Nasdaq Capital Market under the symbol “BIOL.”