Efficient automated solid-phase synthesis of recognition-encoded melamine oligomers.

Recognition-encoded melamine oligomers (REMO) are synthetic polymers with an alternating 1,3,5-triazine-piperazine backbone and side chains equipped with either a phenol or phosphine oxide recognition unit. Here, we describe an automated method for highly efficient solid-phase synthesis (SPS) of REMO of any specified length and sequence. These SPS protocols are amongst the most robust reported to date, as demonstrated by the synthesis of a mixed-sequence 42-mer, which was obtained in excellent crude purity on a 100 mg scale. Starting from loaded Wang resin and dichlorotriazine monomer building blocks, the SPS methods were automated and optimised on a commercial peptide synthesiser. Major side products were identified using LCMS, and the undesired side reactions were suppressed by the choice of resin, solvent and coupling conditions. REMO have been shown to form high-fidelity length- and sequence-selective H-bonded duplexes, analogous to nucleic acids, and automated synthesis will facilitate exploration of related functional properties, such as molecular replication and programmable self-assembly.

Selective Duplex Formation in Mixed Sequence Libraries of Synthetic Polymers.

Recognition-encoded melamine oligomers (REMO) are synthetic polymers that feature an alternating 1,3,5-triazine-piperazine backbone and side-chains equipped with either a phenol or phosphine oxide recognition unit. An automated method for the solid-phase synthesis (SPS) of REMO of any specified sequence has been developed starting from dichlorotriazine monomer building blocks. Complementary homo-oligomers with either six phenols or six phosphine oxides were synthesized and shown to form a stable duplex in nonpolar solvents by NMR denaturation experiments. The duplex was covalently trapped by equipping the ends of the oligomers with an azide and an alkyne group and using a copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction. The SPS methodology was adapted to synthesize mixed sequence libraries by using a mixture of two different dichlorotriazine building blocks in each coupling cycle of an oligomer synthesis. The resulting libraries contain statistical mixtures of all possible sequences. The self-assembly properties of these libraries were screened by using the CuAAC reaction to trap any duplexes present. In mixed sequence libraries of 6-mers, the trapping experiments showed that only sequence-complementary oligomers formed duplexes at micromolar concentrations in dichloromethane. The automated synthesis approach developed here provides access to large libraries of mixed sequence synthetic polymers, and the covalent trapping experiment provides a convenient tool for screening functional properties of mixtures. The results suggest high-fidelity sequence-selective duplex formation in mixtures of 6-mer sequences of the REMO architecture.

Single piece flexible obturator for the management of complex maxillary defects: A clinical report.

Cysts, a common occurrence in the jaws, are managed with different conservative and radical approaches. Although surgical excision is usually the treatment of choice, it can result in an open defect that compromises the oronasal seal and affects the patient's quality of life by interfering with daily intake of nutrition. These defects vary in anatomic geometry and extent depending upon etiology and require a prosthodontic intervention in the intermediate phase until a definitive closure is executed. An unconventional obturator design with a helical spring incorporated into a flexible obturator is described to manage 2 patients with challenging anterior maxillary cysts.

Utilizing DICOM data to generate custom computer-aided designing and computer-aided machining polyetheretherketone healing abutments for an ear prosthesis.

Soft tissue healing around implants may turn out to be the most decisive factor in the success or failure of the prosthesis. Dimension, configuration, and material of the healing abutments play a pivotal role in achieving optimal soft tissue architecture around implants. Digital imaging with computer-aided designing and computer-aided machining (CAD-CAM) technology, has made it easier to illustrate, design, replicate maxillofacial structures, and generate its supporting elements in a reliable, faster, and more convenient manner. This case report highlights the issue relevant to the implant-supported prosthetic replacement, on a site previously attempted for surgical reconstruction of the missing ear. Presurgical DICOM data were used to obtain custom CAD-CAM polyetheretherketone (PEEK) healing abutments on implants in a patient with an excessive amount of tissue in the missing right ear region. It is probably the first extraoral use of PEEK as a healing abutment in the workflow of implant retained maxillofacial prosthetics. No issue warranting the removal of the PEEK component was observed during the duration of its use.

A custom made extraoral aid for retaining interim obturator in edentulous patients with bilateral maxillectomy: A report of four patients.

It is a considerable challenge for a prosthodontist to rehabilitate and sustain the prosthesis in edentulous patients with bilateral maxillectomy. Compelling evidence is lacking with respect to the treatment outcome when the maxillary defects are closed surgically in comparison to their prosthetic rehabilitation. Four edentulous male patients, with bilateral maxillectomy defects were referred for prosthodontic intervention to meet their nutritional and speech issues. In the absence of intra oral supporting and retentive structures, it was decided to retain the obturator utilizing extraoral aid to address their functional needs. Customized headgear face-bow retained obturators were adequately retentive and did serve its purpose well in all four patients. It also gave the liberty to alter retention and refine the prosthesis at will, provided access to the operated site for a quick evaluation of disease recurrence, and was economical to the patients. Considering the encouraging outcome experienced in this special category of individuals, it would be reasonable to believe that the headgear face-bow assembly has an immense potential to function as a valuable, prudent, and a viable retentive aid for a non-implant retained obturator in edentulous patients with extensive maxillary defect.