Purpose: A completely edentulous or partially edentulous maxilla involving missing anterior teeth may impact speech production and lead to reduced speech intelligibility. The aim of this study was to prospectively evaluate the effect of a dental prosthetic rehabilitation on speech intelligibility in patients with a toothless or interrupted maxillary arch by means of an automatic, standardized speech recognition system. Materials and Methods: The speech intelligibility of 45 patients with complete tooth loss or a loss including missing anterior teeth in the maxilla was evaluated by means of a polyphone-based automatic speech recognition system that assessed the percentage of correctly recognized words (word accuracy). To replace inadequate maxillary removable dentures, 20 patients from the overall sample had been rehabilitated with complete dentures and 25 patients with telescopic prostheses. Speech recordings were made in four recording sessions (with and without existing prostheses and then at 1 week and 6 months after placement of newly fabricated prostheses). Results: Significantly higher speech intelligibility was observed in both patient groups compared to the original results without the dentures inserted. After 6 months of adaptation, both groups had reached a level of speech quality that was comparable to the healthy control group. However, patients receiving new telescopic prostheses showed significantly higher levels of speech intelligibility compared to those receiving new complete dentures. Within 6 months, speech intelligibility did not significantly improve from the level found 1 week after insertion of new prostheses for both groups. Conclusion: Patients benefit from the fabrication of new dentures in terms of speech intelligibility, regardless of the type of prosthesis. However, telescopic crown prostheses yield significantly better speech quality compared to complete dentures.