Biofilm Accumulation on Complete-Arch Subperiosteal Implant-Supported Prostheses: Influence of Pontic Design

Pingyi Jia, Jingwen Yang

Full text link: https://pubmed.ncbi.nlm.nih.gov/38233257/

Biofilm Accumulation on Complete-Arch Subperiosteal Implant-Supported Prostheses: Influence of Pontic Design

1. Scientific Reference

• Study Title: Biofilm accumulation on complete arch subperiosteal implant-supported prostheses: Effect of pontic type
• Authors: Pingyi Jia, Jingwen Yang
• Journal: The Journal of Prosthetic Dentistry
• Year of Publication: 2024
• DOI: 10.1016/j.prosdent.2023.12.015

2. Scientific Background

Long-span implant-supported prostheses must provide not only mechanical stability and functional rehabilitation but also allow effective plaque control throughout their lifespan. This challenge becomes particularly relevant in complete-arch restorations supported by subperiosteal implants, where access beneath the prosthesis can be limited. The design of the tissue-facing surface therefore represents an important consideration in prosthetic planning, as it may influence the patient’s ability to maintain adequate oral hygiene.

Although numerous restorative variables have been investigated in implant prosthodontics, the relationship between pontic morphology and biofilm retention beneath complete-arch subperiosteal prostheses has remained insufficiently documented. By examining how different pontic configurations affect simulated plaque accumulation, this experimental study contributes to the understanding of prosthetic design features that may influence maintenance and long-term biological management of implant-supported rehabilitations.

3. Study Objective

The purpose of this in vitro investigation was to determine whether the morphology of the intaglio surface, specifically the pontic design, influences biofilm accumulation beneath complete-arch prostheses supported by subperiosteal implants. The authors also explored whether anatomical variables, including transmucosal height and interimplant distance, were associated with the extent of retained biofilm.

4. Methodology

This research was conducted as an in vitro experimental study.

A total of 68 complete-arch subperiosteal implant-supported prostheses were fabricated with different interimplant distances and four pontic designs: saddle, flat, scalloped, and ovate.

To reproduce biofilm deposition under standardized laboratory conditions, the investigators applied a green aerosol to the intaglio surface of each prosthesis. Following a standardized cleaning procedure using dental floss, the restorations were digitized with an intraoral scanner. Residual colored areas were identified through a three-dimensional macroscopic quantification method to estimate biofilm retention. Interimplant distance and transmucosal height were also measured. Statistical analyses included Spearman correlation testing and generalized estimating equation (GEE) models adjusted for prosthesis location, cantilever presence, implant spacing, and transmucosal height.

5. Main Findings

The study demonstrated a significant association between transmucosal height and biofilm accumulation, with a reported correlation coefficient of 0.208 (P < .001), suggesting that increasing transmucosal height influences the amount of retained biofilm beneath the pontic region.

After adjustment for multiple prosthetic and anatomical variables, the generalized estimating equation models consistently showed that saddle pontics accumulated significantly more simulated biofilm than the other pontic configurations evaluated.

Conversely, flat and ovate pontics exhibited significantly lower levels of biofilm retention, indicating a more favorable intaglio morphology for plaque removal within the limitations of this laboratory model. The information provided does not report additional significant findings regarding interimplant distance beyond the analyses performed.

6. Clinical Analysis

Rather than focusing exclusively on prosthetic strength or esthetics, this investigation highlights the importance of prosthesis design from a maintenance perspective. Successful implant rehabilitation depends not only on surgical and restorative accuracy but also on the patient’s long-term ability to control plaque around the restoration.

Within the experimental conditions of this study, pontic geometry appeared to influence how readily simulated biofilm could be removed from the tissue-facing surface. The lower biofilm retention observed with flat and ovate pontics suggests that these designs may facilitate hygiene compared with saddle pontics, which create a more extensive tissue-contacting surface.

The observed relationship between transmucosal height and biofilm retention further indicates that soft-tissue dimensions should also be considered during prosthetic planning.

These findings should nevertheless be interpreted cautiously. The study was conducted under laboratory conditions using a simulated biofilm model, which cannot fully reproduce the complexity of the oral environment, including saliva, bacterial colonization, patient-specific hygiene practices, masticatory function, and biological tissue responses. Consequently, while the results provide valuable information for prosthetic design, they should not be interpreted as definitive clinical recommendations without confirmation through human clinical studies.

7. Clinical Applications

The findings may assist clinicians involved in the design of complete-arch implant-supported prostheses, particularly when long-term maintenance and accessibility for oral hygiene are important treatment objectives.

When planning prosthetic restorations on subperiosteal implants, consideration of pontic morphology may help optimize the cleansability of the prosthesis. These observations may also be relevant within digital implant workflows and CAD/CAM prosthetic fabrication, where intaglio surface design can be precisely controlled during restoration planning.

The available data do not support extending these conclusions to other implant-supported prosthetic designs or clinical scenarios beyond those investigated.

8. Level of Evidence, Limitations and Transparency

This investigation is an in vitro experimental study, representing preclinical evidence rather than direct clinical evidence.

Its methodology provides controlled experimental conditions and appropriate statistical analyses; however, laboratory simulations cannot fully reproduce the biological complexity of intraoral plaque formation and maintenance.

Beyond the inherent limitations associated with an in vitro design, the abstract does not provide additional methodological limitations.

No conflicts of interest or industry affiliations are reported within the information provided.

9. Key Points

• Study type: In vitro experimental study.
• Level of evidence: Preclinical laboratory investigation.
• Sample: 68 complete-arch subperiosteal implant-supported prostheses.
• Follow-up: Not applicable.
• Primary outcome: Biofilm accumulation on the intaglio surface according to pontic morphology.
• Main finding: Saddle pontics retained significantly more simulated biofilm than the other pontic designs.
• Additional finding: Greater transmucosal height was significantly associated with increased biofilm accumulation.
• Scientific conclusion: Pontic morphology and transmucosal height influence biofilm retention under the experimental conditions investigated.
• Limitations: In vitro design; additional methodological limitations are not specified in the available abstract.

10. Scientific Impact

This study expands current knowledge regarding prosthetic design considerations beyond mechanical performance by addressing a factor directly related to maintenance and biological health. It suggests that the morphology of the intaglio surface may influence plaque retention and therefore deserves consideration during the design phase of complete-arch implant-supported prostheses.

Although the findings originate from a laboratory model and require validation in clinical settings, they provide an experimental basis for future investigations evaluating how prosthetic design affects long-term peri-implant maintenance. The study contributes to ongoing efforts aimed at improving prosthetic rehabilitation through designs that facilitate oral hygiene while maintaining functional and restorative objectives.

11. Editorial Conclusion

This preclinical study indicates that pontic morphology influences simulated biofilm retention beneath complete-arch subperiosteal implant-supported prostheses. Flat and ovate pontic designs demonstrated lower biofilm accumulation than saddle pontics within the experimental model, while transmucosal height also showed a measurable association with plaque retention. Although clinical confirmation remains necessary, these findings encourage greater attention to prosthetic cleansability during the design of complex implant-supported rehabilitations.