In Maples v. Workers' Comp. Appeals Bd. (1980) 111 Cal.App.3d 827, the court held that the WCAB erred in permitting the insurance carrier for the employer to claim an overpayment of temporary disability indemnity payments against petitioner's permanent disability award. (Maples, supra, 111 Cal.App.3d at pp. 829-830.) The carrier had received a medical evaluation opinion in November of 1977 that found the employee to be permanent and stationary. (Id. at p. 830.) However, the first notice the carrier gave the employee of the opinion was in a supplemental medical report from the same doctor, filed and served in September 1978, reaffirming the permanent and stationary status opinion as of the date of the prior examination and report. (Ibid.) The carrier stopped paying temporary disability indemnity as of August 9, 1978, but did not immediately advise the employee of the reason for the termination. (Maples, at pp. 830-831.) The Maples opinion held the carrier estopped, as a matter of law, from claiming that temporary disability ended prior to the employee's receipt of the report containing the opinion his condition was permanent and stationary. (Maples, supra, 111 Cal.App.3d at p. 839.) The opinion notes that the carrier had violated provisions of the Labor Code and WCAB rules in failing to timely file with the appeals board and serve on the employee the original medical report and in failing to file a petition to terminate temporary disability indemnity within 10 days of the cessation of payments. (Id. at pp. 834-835.) The full disclosure of medical reports as required by WCAB rules is essential to the expeditious determination of the controversies submitted to the appeals board and failure to disclose is prejudicial to the injured worker. This prejudice is, inter alia, that the allowance of credit for a temporary disability overpayment can be disruptive of the purpose of permanent disability indemnity, delay receipt by the injured worker of additional workers' compensation benefits and his return to employment, and prevent the worker's doctor from recommending further medical or surgical procedures. (Id. at pp. 836-837.)