Section 19

to the effect that at any time or during any period specified in the certificate any person was or was not a registered dentist, or had or did not have in force a practising certificate; or (b)as to any entry in the appropriate register, or the removal from the appropriate register of any entry,shall, in the absence of proof to the contrary, and without further proof of the signature appended to the certificate, be sufficient evidence of the matters specified therein.