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BACKGROUND: Non-carious cervical lesions (NCCLs) refer to the loss of dental hard tissue in the cervical region due to physical and/or chemical factors, often associated with the disappearance of the cemento-enamel junction (CEJ), posing challenges in both diagnosis and treatment of gingival recessions (GR). This case study introduces two protocols for multidisciplinary CEJ reconstruction prior to the root coverage therapy (RCT). METHODS: Two patients with GR and NCCLs were treated using two CEJ reconstruction techniques: both, analogically and digitally guided. For each case, the position of the therapeutic CEJ was predetermined using a combination of the methods described by Zucchelli and Cairo. Then, an analog or digital diagnostic wax-up was performed accordingly. In the analogically guided technique, a transparent silicone guide matrix was used to transfer information from the dental wax-up. In contrast, the digitally guided technique employed a rigid, translucent resin prosthetic guide matrix that was designed and printed. Restorations were fabricated using direct composite resin and RCT was performed 1 week later in both techniques. RESULTS: At 6 months, both cases demonstrated complete root coverage and effective healing of the soft tissues surrounding the restorations. CONCLUSIONS: Dimensional changes in materials and precise guide adjustment in the analog technique are operator-dependent and can affect the outcomes. Digital procedures, though effective, are costly and may limit their use. The usage of these two CEJ reconstruction techniques enhances communication within the multidisciplinary team and ensures optimal aesthetic outcomes and precise placement of the gingival margin. KEY POINTS: There are no established clinical protocols described in the literature for reconstructing the cemento-enamel junction (CEJ) once the position of a therapeutic CEJ has been predetermined and prior root coverage therapy (RCT). Performing a diagnostic wax-up (analogically or digitally) to reconstruct the therapeutic CEJ is crucial and facilitates the creation of a prosthetic guide that accurately reproduces the defined CEJ position. The reconstruction of the CEJ may improve the prognosis of RCT. PLAIN LANGUAGE SUMMARY: This study looked at a dental issue called non-carious cervical lesions, which happens when the hard tissue near the gum line of a tooth wears away, making it harder to treat gum recession. Two different approaches were tested to rebuild the lost tissue in the gum area before performing a procedure to cover the exposed roots. One approach used traditional methods with physical guides to help place the new tissue, while the other used advanced digital techniques to create a precise guide using 3D printing. After 6 months, both methods successfully covered the exposed roots and helped the gums heal properly. However, the traditional method's results can vary depending on the dentist's skill, while the digital method, although more accurate, can be expensive. Using these methods can improve teamwork among dental specialists and lead to better-looking results by ensuring the gum line is placed exactly where it should be.
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This study aimed to characterize the role of Pseudomonas aeruginosa low-molecular-mass penicillin-binding proteins (LMM PBPs), namely, PBP4 (DacB), PBP5 (DacC), and PBP7 (PbpG), in peptidoglycan composition, ß-lactam resistance, and ampC regulation. For this purpose, we constructed all single and multiple mutants of dacB, dacC, pbpG, and ampC from the wild-type P. aeruginosa PAO1 strain. Peptidoglycan composition was determined by high-performance liquid chromatography (HPLC), ampC expression by reverse transcription-PCR (RT-PCR), PBP patterns by a Bocillin FL-binding test, and antimicrobial susceptibility by MIC testing for a panel of ß-lactams. Microscopy and growth rate analyses revealed no apparent major morphological changes for any of the mutants compared to the wild-type PAO1 strain. Of the single mutants, only dacC mutation led to significantly increased pentapeptide levels, showing that PBP5 is the major dd-carboxypeptidase in P. aeruginosa. Moreover, our results indicate that PBP4 and PBP7 play a significant role as dd-carboxypeptidase only if PBP5 is absent, and their dd-endopeptidase activity is also inferred. As expected, the inactivation of PBP4 led to a significant increase in ampC expression (around 50-fold), but, remarkably, the sequential inactivation of the three LMM PBPs produced a much greater increase (1,000-fold), which correlated with peptidoglycan pentapeptide levels. Finally, the ß-lactam susceptibility profiles of the LMM PBP mutants correlated well with the ampC expression data. However, the inactivation of ampC in these mutants also evidenced a role of LMM PBPs, especially PBP5, in intrinsic ß-lactam resistance. In summary, in addition to assessing the effect of P. aeruginosa LMM PBPs on peptidoglycan structure for the first time, we obtained results that represent a step forward in understanding the impact of these PBPs on ß-lactam resistance, apparently driven by the interplay between their roles in AmpC induction, ß-lactam trapping, and dd-carboxypeptidase/ß-lactamase activity.