i would advice antibiotic coverage, followed by extraction of 3rd molar, then endodotic therapy of 2nd molar, as after endontic treatment of 2nd molar there might be leverage of forces while removing 3rd molar which might fracture the then brittle non vital 2nd molar
i would advice a proper try of ceramic veneers using glycerine which is ideal to check the fit and the shade matching
, followed by a thorough isolation , and acidetch protocal and priming and bonding using dual cure resin cements viz- Panavia
and to prevent the slight dicolouration of prepared tooth the shade of base cements can be modified by using Dual cure cement-Variolink (ivoclar Vivadent)