Year Ended December 31, (in thousands, except share data)      2000     1999     1998 Operating Activities Net income (loss)  $ (2,854 )   $ 45,836  $ 33,813 Adjustments to reconcile net income (loss)  to net cash provided by operating activities:   Provision for bad debt expense 373 2,079 2,295   Depreciation and amortization 15,175 12,238 9,124   Deferred income taxes (7,792 )  1,273 (2,767 )    Cumulative effect of changes in accounting principles 50,576 678 —   Changes in operating assets and liabilities:     Service fee receivables (13,549 )  (27,491 )  (22,733 )      Supplies inventory 889 (2,305 )  (2,663 )      Prepaid expenses and other (2,309 )  (1,342 )  228     Advances to/amounts payable to orthodontic entities (8,233 )  (2,420 )  (1,756 )      Accounts payable and other current liabilities 7,368 (5,199 )  6,568 Net cash provided by operating activities 39,644 23,347 22,109 Investing Activities Purchases of property, equipment and improvements (20,271 )  (22,520 )  (17,638 )  Proceeds from (sales of) available-for-sale investments (16 )  204 19,674 Intangible assets acquired (28,246 )  (17,178 )  (42,216 )  Advances to orthodontic entities — (3,951 )  (4,906 )  Payments from orthodontic entities — 370 1,927 Net cash used in investing activities (48,533 )  (43,075 )  (43,159 )  Financing Activities Repayment of notes payable to affiliated orthodontists and long-term debt (6,530 )  (6,742 )  (7,864 )  Proceeds from long-term debt 7,483 30,577 20,055 Repayment of loans from key employee program 2,632 — — Issuance of common stock 4,299 114 595 Net cash provided by financing activities 7,884 23,949 12,786 Foreign currency translation adjustment (127 )  — — Change in cash and cash equivalents (1,132 )  4,221 (8,264 )  Cash and cash equivalents at beginning of year 5,822 1,601 9,865 Cash and cash equivalents at end of year  $ 4,690  $ 5,822  $ 1,601 Supplemental Cash Flow Information Cash paid during the year for:   Interest  $ 4,271  $ 2,499  $ 337   Income taxes  $ 31,568  $ 33,931  $ 19,287 Supplemental Disclosure of Noncash Investing and Financing Activities Notes payable and common stock issued to obtain Service Agreements  $ 5,974  $ 4,512  $ 13,609         See accompanying notes.