Soft and hard tissue evaluation of guided socket shield implant cases.

BACKGROUND: The socket-shield (SS) technique results in long-term functional osseo- and dento-integration, preserving the dimensional stability of hard and soft tissues over time. This study aimed to describe the successful implementation of a surgical technique to facilitate "SS" cases. METHODS: The cases included males and females aged 32-81 years consecutively treated between 2020 and 2023 (longest follow-up, 3.5 years). For each case, pre- and post-operative cone-beam computed tomography (Digital Imaging and Communications in Medicine files) and intraoral optical scans (IOS; STL files) were performed. Digital immediate implant placement and simultaneous tooth extraction and SS production were planned using an implant planning software. Implants were planned considering sagittal-ridge and tooth-root angular-configuration. Surgical guides were used to perform the digitally-supported SS technique. All cases were planned and surgically performed by one operator (Pedro M. Trejo). Preoperative digital IOS-models were superimposed to post-operative models to assess soft-tissue changes. Pre and post sagittal views were used to assess the radiographic buccal-plate thickness at various healing times. An investigator not involved with case planning or treatment performed measurements. RESULTS: Results reflected soft-tissue stability with minimal mean thickness change at 0-, 1-, 2-, and 3-mm measurement levels of 0.03, -0.2, 0.14, -0.07, and 0.04 mm, respectively, with a mean gingival-margin change of 0.04 mm. The free gingival-margin change ranged from a 0.58-mm gain in height to a -0.57-mm loss. The mean radiographic buccal-plate thickness post-operatively was 2.04 mm (range, 0.7-2.9 mm). CONCLUSION: The digitally-supported guided SS technique enables predictable immediate implant-placement positions and stable buccal peri-implant soft and hard tissues over time. KEY POINTS: Why are these cases new information? The uniqueness of the surgical technique described herein is that it results in favorable positions of immediate, socket-shielded (SSed), implant placements, with soft- and hard-tissue stability as the byproduct. What are the keys to successful management of these cases? Digitally, plan for the best possible implant position within the alveolar housing to satisfy prosthetic requirements, and then adjust this position to accommodate the socket shield dimensions. Digitally, provide a space/gap between the future dentinal shield and the implant. Clinically, allow for time to carve the final position and dimensions of the shield. Plan ahead the extent of the apical third of the SS, and the removal of the apex, if dealing with a long root. What are the primary limitations to success in these cases? Inadequate use of digital technology; case-sensitive technique requires proper execution of each digital and technical clinical step.

Improvement in salt-tolerance of Aspergillus oryzae γ-glutamyl transpeptidase via protein chimerization with Aspergillus sydowii homolog.

γ-Glutamyl transpeptidase is one of the key enzymes involved in glutamate production during high-salt fermentation of soy sauce and miso by koji mold, Aspergillus oryzae. However, the activity of γ-glutamyl transpeptidase from A. oryzae (AOggtA) is markedly reduced in the presence of NaCl, thus classifying it as a non-salt-tolerant enzyme. In contrast, the homologous protein from the xerophilic mold, A. sydowii (ASggtA) maintains its activity under high-salt conditions. Therefore, in this study, a chimeric enzyme, ASAOggtA, was designed and engineered to improve salt-tolerance in AOggtA by swapping the N-terminal region, based on sequence and structure comparisons between salt-tolerant ASggtA and non-salt-tolerant AOggtA. The parental AOggtA and ASggtA and their chimera, ASAOggtA, were heterologously expressed in A. oryzae and purified. The chimeric enzyme inherited the superior activity and stability from each of the two parent enzymes. ASAOggtA showed > 2-fold greater tolerance than AOggtA in the presence of 18% NaCl. In addition, the chimera showed a broader range of pH stability and greater thermostability than ASggtA. AOggtA and ASAOggtA were sy over the range pH 3.0 to pH 10.5. Thermal stability was found to be in the order AOggtA (57.5 °C, t1/2 = 32.5 min) > ASAOggtA (55 °C, t1/2 = 20.5 min) > ASggtA (50 °C, t1/2 = 12.5 min). The catalytic and structural characteristics indicated that non-salt-tolerant AOggtA would not undergo irreversible structural changes in the presence of NaCl, but rather a temporary conformational change, which might result in reducing the substrate binding and catalytic activity, on the basis of kinetic properties. In addition, the chimeric enzyme showed hydrolytic activity toward L-glutamine that was as high as that of AOggtA. The newly-designed chimeric ASAOggtA might have potential applications in high-salt fermentation, such as miso and shoyu, to increase the content of the umami-flavor amino acid, L-glutamate.

Isolation and characterization of a salt-tolerant γ-glutamyl transpeptidase from xerophilic Aspergillus sydowii.

Xerophilic Aspergillus molds isolated from halo-alkaliphilic and dry environments are attractive genetic resources for obtaining salt- and osmo-adaptive enzymes. A. sydowii MA0196 secreted the largest amount of γ-glutamyl transpeptidase (GGT) during solid-state fermentation at a low initial water activity (a w = 0.85). Gel filtration analysis revealed that the molecular mass of the purified native enzyme (MA0196 GGT) was 120 kDa. SDS-PAGE analysis showed that MA0196 GGT consists of two subunits with molecular masses of 56.4 and 33 kDa, indicating production from a proenzyme via autoproteolysis. Deglycosylation of the subunits by N-glycosidase F yielded 40.9 and 19.6 kDa species. MA0196 GGT retained transpeptidase and hydrolysis activities and their catalytic efficiency (k cat/K m) under high salt and low water activity. The enzyme displayed broad substrate specificity toward γ-glutamyl acceptors such as amino acids and the imidazole dipeptides, carnosine and anserine. Carnosine and L-glutamine were converted into γ-glutamyl-ß-alanyl-L-histidine by MA0196 GGT with a 32.9% yield in the presence of 2% (v/v) dimethyl sulfoxide. Phylogenetic analysis indicated that MA0196 GGT forms a distinct lineage from A. oryzae and A. sojae GGTs. These excellent properties indicate that MA0196 GGT can be used in salted fermentation and for producing bioactive peptides. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-022-03259-3.