Mastoid Obliteration Using Bioceramic Scaffold After Canal Wall Down Mastoidectomy: A Systematic Review

Abstract

Canal wall down mastoidectomy (CWD) effectively eradicates cholesteatoma and chronic otitis media but frequently results in a problematic open mastoid cavity. Mastoid obliteration aims to reduce cavity-related morbidity. Bioceramic materials, including hydroxyapatite (HA), tricalcium phosphate (TCP), and bioactive glass (BAG), have been increasingly adopted because of their osteoconductive, biocompatible, and antimicrobial properties. This systematic review evaluates the clinical outcomes and complications of bioceramic mastoid obliteration following CWD. A systematic literature search of PubMed, Scopus, and Web of Science was conducted for studies published between 2005 and 2025, following PRISMA guidelines. Clinical studies reporting outcomes of bioceramic mastoid obliteration after CWD were included. Thirteen clinical studies were included. HA-, TCP-, and BAG-based materials demonstrated high obliteration success rates (>90% in most series). BAG S53P4 was consistently associated with low infection rates and favorable epithelialization, whereas earlier HA cement formulations were occasionally associated with revision-requiring complications. Bioceramic scaffolds represent safe and effective materials for mastoid obliteration after CWD. BAG offers additional antibacterial advantages, while HA provides predictable volume stability. Further prospective and comparative studies are required to establish material superiority and long-term outcomes.

1. Introduction

Cholesteatoma is a destructive epithelial lesion characterized by keratinizing squamous epithelium within the middle ear and mastoid, capable of progressive bone erosion and severe complications, including hearing loss, vestibular dysfunction, facial nerve paralysis, and intracranial involvement [1,2]. The canal wall down mastoidectomy is commonly used for the eradication of chronic otitis media with cholesteatoma. Unfortunately, even with careful surgical technique, over 10% of patients experience the complication of developing a troublesome mastoid cavity [1,2]. Mastoid obliteration aims to replace the open mastoid cavity with viable material that is devoid of cholesteatoma and infection. The resulting epithelized lateral surface ablates the mucosalized and pneumatized mastoid space while isolating the mucosalized mesotympanic space [3]. The primary goals of obliteration include reducing chronic drainage, preventing cavity-related complications, improving cosmesis, and enabling safer imaging modalities postoperatively. The choice of obliteration material is crucial, as it must support tissue integration, resist infection, and maintain structural volume over time. Traditional obliteration materials include autologous fat, bone pâté, or cartilage [2,3]. Although autologous materials are the greatest choice for reconstructing the posterior ear canal and mastoid obliteration, they have drawbacks such as donor site morbidity, atrophy, resorption, and difficulty in fashioning. Finding enough material is frequently difficult due to the volume of prior operations [4]. Other methods include “allografting,” which uses bone tissue from another individual, and “xenografting,” which uses bone grafts made from animal tissues. However, complications, including tissue incompatibility, increased immunological reactions, and the possibility of disease transfer, could result from these techniques. Allografts also lead to a delayed osseointegration process.

Due to the swift advancements in biomaterials over the past few years, mastoid obliteration can effectively solve these issues. Both biological and synthetic materials may be utilized for the process of mastoid obliteration.

Bioceramic materials—engineered ceramics designed for use in biological environments—have emerged as an ideal class of scaffolds for otologic reconstruction [2]. These materials, including hydroxyapatite (HA), tricalcium phosphate (TCP), and bioactive glass, mimic the mineral phase of bone and are inherently osteoconductive. They have emerged as promising alternatives in mastoid obliteration due to their osteoconductivity, biocompatibility, and long-term stability. Their success in craniofacial and orthopedic applications has led to increased interest in otologic use [5,6]. HA resembles natural bone mineral in structure and composition, allowing for osteoconduction and long-term volumetric stability. One kind of glass–ceramic biomaterial that adheres to bone and promotes tissue regeneration is called bioactive glass. It develops a coating on its surface that resembles hydroxyapatite after implantation, enabling it to fuse with bone cells and eventually be replaced by new bone. It is helpful in dental and orthopedic applications, including bone healing, enamel rebuilding, and implant coatings, because of its biocompatibility and osteogenic potential.

The S53P4 bioactive glass (BAG) variant, in particular, has demonstrated superior antibacterial properties, making it highly suitable for infected mastoid cavities or revision surgery. Clinical studies report decreased bacterial biofilm formation and reduced need for long-term antibiotics when using BAG [7].

This systematic review synthesizes contemporary clinical evidence on the outcomes and complications of bioceramic mastoid obliteration following CWD, with emphasis on material-specific performance and emerging tissue engineering strategies.

2. Materials and Methods

2.1. Protocol and Reporting

This systematic review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guideline.

2.2. Search Strategy

A comprehensive literature search of PubMed, Scopus, and Web of Science was performed for articles published between January 2005 and June 2025 (Figure 1). Search terms included “mastoid obliteration,” “bioceramic,” “hydroxyapatite,” “bioactive glass,” “tricalcium phosphate,” and “temporal bone.” Reference lists of included studies were manually screened.

2.3. Eligibility Criteria

Inclusion criteria were clinical studies or case series involving at least five patients, use of bioceramic materials for mastoid or epitympanic obliteration following CWD, a minimum follow-up of six months, and reporting of clinical outcomes or complications.

Exclusion criteria included case reports with fewer than five patients, purely preclinical studies, non-English articles, conference abstracts without full text, and studies lacking outcome data specific to bioceramic obliteration.

2.4. Study Selection and Data Extraction

Two independent reviewers screened titles, abstracts, and full texts. Disagreements were resolved by consensus. Extracted data included material type, surgical technique, number of ears, follow-up duration, clinical outcomes, complications, and radiologic findings.

2.5. Risk of Bias Assessment

The risk of bias of included studies was independently assessed by two reviewers using the ROBINS-I tool for non-randomized studies. The following domains were evaluated: bias due to confounding, selection of participants, classification of interventions, deviations from intended interventions, missing data, measurement of outcomes, and selective reporting. Disagreements were resolved by consensus.

3. Results

3.1. Clinical Outcomes

The reviewed studies consistently reported favorable outcomes with the use of bioceramic scaffolds in mastoid obliteration (Table 1, Table 2 and Table 3). Across the 13 studies analyzed, obliteration success rates exceeded 90% in most series [8,9,10,11]. Integration of the scaffold into native bone was confirmed through postoperative imaging, such as CT or MRI, in the majority of patients. In particular, hydroxyapatite-based scaffolds exhibited minimal resorption and maintained volume long-term [12,13].

The difference between biological HA and synthetic HA was studied. Whereas synthetic HA is produced chemically, biologic HA is HA that is found in natural sources such as bones. Although they have the same chemical formula (Ca₁₀(PO₄)₆(OH)₂), synthetic and biological HA are different in terms of composition, structure, and characteristics [14]. Synthetic HA is more homogeneous and pure, while biologic HA has inherent inadequacies and substitutions that affect its bioactivity and rate of degradation. While naturally produced HA can provide improved mechanical performance and particular biofunctions from trace elements, synthetic HA is frequently employed in dental and orthopedic implants because of its biocompatibility and capacity to promote bone formation [14]. In Jang et al.’s preclinical study, after 12 weeks of mastoid obliteration using Sprague–Dawley, neither biological HA nor artificial synthetic HA showed any indications of resorption. Micro-CT and confocal microscopy results, however, showed that the biological HA group’s rapid osteoconductive bone growth was superior to that of the artificial synthetic HA group [15]. After mastoid obliteration using allograft bone and BAG, the postoperative assessment revealed that bone allografts was disappointing in early follow-up, with significant resorption leading to a 40.0% revision surgery rate [16]. Both kinds of HA are widely utilized in dentistry and medicine for orthopedic purposes, dental implants, and bone regeneration. The particular application and required qualities frequently determine which of the biological and synthetic HA is best [17].

Recently, Linderboom et al. performed mastoid obliteration with HA vs. bone pâté in CWD with cholesteatoma and chronic suppurative otitis media [11]. According to an evaluation of mastoid obliteration, bone pâté and HA are safe and efficient obliteration materials that respect the short-term limitation and have high success rates in producing a dry ear, low recidivism rates, and good hearing outcomes. Furthermore, our research indicates that, in contrast to bone pâté, hydroxyapatite causes fewer postoperative wound infections.

BGA is distinguished by its capacity to adhere to teeth and bone. Although the parent bioactive glasses are amorphous, heat treatment is a particular procedure that causes partial crystallization, producing a glass–ceramic material that combines the bioactivity of the glass with the improved mechanical qualities (such as high strength and fracture toughness) of the crystalline phases. It is a composite material that contains two distinct crystalline phases, apatite and beta-wollastonite, as well as a residual amorphous glassy phase [18]. Even when the body was subjected to load-bearing circumstances, it demonstrated bioactivity and a rather high mechanical strength that only gradually declined [19]. The bioactive glasses have the ability to promote the creation of new bone tissue, adhere to the surrounding soft and hard tissues, change into a substance resembling hydroxyapatite both in vitro and in vivo, and release ions that stimulate the expression of osteogenic genes [20]. Although they both aid in bone regeneration, HA and BAG work in different ways. Superior osteoinductive and osteoconductive effects can result from BAG’s faster resorption and ion release, as well as its capacity to customize its composition and properties [21,22]. This makes it a more adaptable and perhaps more useful material for bone regeneration in specific applications. Compared to mastoidectomy alone, obliteration of the mastoid cavity utilizing BAG S53P4 considerably improves the accomplishment of a dry and safe ear in patients with continuously discharging noncholesteatomatous chronic otitis media. Crucially, S53P4 BAG obliteration did not result in any negative outcomes [23].

Several studies evaluated postoperative hearing outcomes [11,24]. Although mastoid obliteration is not primarily aimed at hearing restoration, patients undergoing concurrent tympanoplasty procedures often showed stable or improved air–bone gaps postoperatively. The obliteration also minimized debris accumulation and reduced the frequency of cavity cleaning in canal wall down mastoidectomy cases. Vivicorsi et al. [25] compared the HA between BAG. When evaluating the mid-term viability and stability of biomaterial grafts, postoperative CT scans of mastoid obliteration appear to be a valid method. BHA appears to offer more optimal osseointegration than BAG, with no discernible differences in graft resorption and clinical tolerance.

3.2. Complications

Reported complication rates were low. No scaffold-related infections or long-term foreign-body reactions were reported. Bioactive glass scaffolds demonstrated added benefit by reducing postoperative infection rates, possibly due to their intrinsic antibacterial ion release [26,27].

Recently, Choong et al. reported a systematic review of the complications of mastoid obliteration materials [10]. A total of 2578 ears were taken into consideration. The autologous group experienced 142 (6.8%) serious problems and 165 (7.9%) mild issues overall. The overall rate of complications is 14.8%. Recurrent and lingering disease necessitating revision surgery were the main consequences. The allogenic group experienced three (5.6%) serious problems and ten (18.5%) mild issues. The cumulative complication rate was 24%.

Table 1. Summary of included clinical studies on mastoid obliteration using bioceramic scaffolds (2005–2025).

Author	Ears	Material and FU Duration	Results and Complications	Ref.
Hashimi S et al. [28]	26	HA cement, 1 yr	1 case explantation. EAC granulation, wound dehiscence.	J Laryngol Otol. 2025;139(6):458–463
Liu M et al. [29]	56	HA	achieved complete epithelialization within 60 days post-operation was significantly higher in the CGF/HA group than in the HA group.	Braz J Otorhinolaryngol 2025;91(3):101561
Chomarat J et al. [30]	236	108 control, 66 Bone pâté, 62 BAG	Highlights the benefits of bone pâté obliteration versus BAG.	Eur Arch Otorhinolaryngol 2025;282(11):5635–5643
Kroon VJ et al. [31]	208	124 BAG. 84 non-ob 1 year	Continuous discharge: 1, revision: 10 in the non-obliteration group.	Otol Neurotol 2025;46(8):949–955
Zwiez A et al. [32]	28	21 sticky bone, 7 BAG 9 months	No difference between the 2 groups.	J Clin Med 2025;14(5):1681
Kroon VJ et al. [33]	97	97 BAG 3.9 years	Only 1 retroauricular skin defect. Ossiculoplasty: 42, 11.2 dB improvement.	OTO Open 2023;7(4):e96.
G Leonard C et al. [34]	90	BAG 6.59 months	Recurred cholesteatoma: 2, delayed healing: 12. In all cases, conservative management resulted in complete healing.	J Int Adv Otol 2021;17(3):234–238.
Sorour SS et al. [35]	20	BAG 1–3 years	No granulation, foreign-body reaction, or extrusion; no displacement of BAG material No recurrent facial palsy or cholesteatoma Significant hearing improvement.	Am J Otolaryngol 2018;39(3):282–285.
Sahli-Vivicorsi S et al. [16]	21	Biological HA vs. BAG 10.4 months	Biological HA seems to provide a more optimal osseointegration versus BG, with no significant differences in graft resorption and clinical tolerance.	Eur Arch Otorhinolaryngol 2022;279(9):4379–4388
Yung M et al. [36]	140 revision	HA	Revision mastoidectomy using HA was highly successful in converting troublesome mastoid cavities into dry, water-resistant ears. The cumulative complication rate was 16.6%.	J Laryngol Otol 2011;125(3):221–226
Minoda R et al. [37]	12	Beta-TCP	53.8 months TBCT, no continuous discharge,	Otol Neurotol 2007;28(8):1018–1021
Yanagihara N et al. [38]	42	Bone pâté combined with HA for 1 year CWUMT with mastoid obliteration Second-stage ossiculoplasty 1 year after the first-stage operation	No postoperative complications nor residual cholesteatoma were encountered.	Otol Neurotol 2009;30(6):766–770
Vos J et al. [23]	23	BAG, 2.4 years (1.1–4.1) CWD or CWU with mastoid obliteration	Safe and not prone to adverse events. The positive effect of BAG is more prominently observed in revision procedures.	Eur Arch Otorhinolaryngol 2017;274(12):4121–4126.

Table 1. Summary of included clinical studies on mastoid obliteration using bioceramic scaffolds (2005–2025).

Author	Ears	Material and FU Duration	Results and Complications	Ref.
Hashimi S et al. [28]	26	HA cement, 1 yr	1 case explantation. EAC granulation, wound dehiscence.	J Laryngol Otol. 2025;139(6):458–463
Liu M et al. [29]	56	HA	achieved complete epithelialization within 60 days post-operation was significantly higher in the CGF/HA group than in the HA group.	Braz J Otorhinolaryngol 2025;91(3):101561
Chomarat J et al. [30]	236	108 control, 66 Bone pâté, 62 BAG	Highlights the benefits of bone pâté obliteration versus BAG.	Eur Arch Otorhinolaryngol 2025;282(11):5635–5643
Kroon VJ et al. [31]	208	124 BAG. 84 non-ob 1 year	Continuous discharge: 1, revision: 10 in the non-obliteration group.	Otol Neurotol 2025;46(8):949–955
Zwiez A et al. [32]	28	21 sticky bone, 7 BAG 9 months	No difference between the 2 groups.	J Clin Med 2025;14(5):1681
Kroon VJ et al. [33]	97	97 BAG 3.9 years	Only 1 retroauricular skin defect. Ossiculoplasty: 42, 11.2 dB improvement.	OTO Open 2023;7(4):e96.
G Leonard C et al. [34]	90	BAG 6.59 months	Recurred cholesteatoma: 2, delayed healing: 12. In all cases, conservative management resulted in complete healing.	J Int Adv Otol 2021;17(3):234–238.
Sorour SS et al. [35]	20	BAG 1–3 years	No granulation, foreign-body reaction, or extrusion; no displacement of BAG material No recurrent facial palsy or cholesteatoma Significant hearing improvement.	Am J Otolaryngol 2018;39(3):282–285.
Sahli-Vivicorsi S et al. [16]	21	Biological HA vs. BAG 10.4 months	Biological HA seems to provide a more optimal osseointegration versus BG, with no significant differences in graft resorption and clinical tolerance.	Eur Arch Otorhinolaryngol 2022;279(9):4379–4388
Yung M et al. [36]	140 revision	HA	Revision mastoidectomy using HA was highly successful in converting troublesome mastoid cavities into dry, water-resistant ears. The cumulative complication rate was 16.6%.	J Laryngol Otol 2011;125(3):221–226
Minoda R et al. [37]	12	Beta-TCP	53.8 months TBCT, no continuous discharge,	Otol Neurotol 2007;28(8):1018–1021
Yanagihara N et al. [38]	42	Bone pâté combined with HA for 1 year CWUMT with mastoid obliteration Second-stage ossiculoplasty 1 year after the first-stage operation	No postoperative complications nor residual cholesteatoma were encountered.	Otol Neurotol 2009;30(6):766–770
Vos J et al. [23]	23	BAG, 2.4 years (1.1–4.1) CWD or CWU with mastoid obliteration	Safe and not prone to adverse events. The positive effect of BAG is more prominently observed in revision procedures.	Eur Arch Otorhinolaryngol 2017;274(12):4121–4126.

3.3. Comparative Outcomes Based on Material Type

HA-based scaffolds were most commonly used and showed consistent obliteration success, long-term volume maintenance, and high biocompatibility. β-TCP scaffolds, while resorbable and osteoconductive, had mixed results in terms of volume preservation. Bioactive glass offered superior infection resistance and epithelialization benefits. Future comparative trials may help determine the superiority of each bioceramic type and composite formulation based on patient-specific factors and surgical indication.

Overall, the included studies demonstrated low to moderate risk of bias (Table 2 and Table 3). The most frequent sources of bias were confounding and participant selection, reflecting the predominantly retrospective and non-randomized study designs. Outcome measurement and reporting bias were generally low, as most studies reported objective clinical and radiologic outcomes. No study was judged to have a critical risk of bias.

Table 2. Risk of bias assessment of included studies using the ROBINS-I.

Study (First Author, Year)	Confounding	Selection of Participants	Classification of Intervention	Deviations from Intended Intervention	Missing Data	Outcome Measurement	Selective Reporting	Overall Risk
Hashmi et al., 2025 [28]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Liu et al., 2025 [29]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Chomarat et al., 2025 [30]	Moderate	Moderate	Low	Low	Moderate	Moderate	Low	Moderate
Kroon et al., 2025 [31]	Moderate	Low	Low	Low	Low	Moderate	Low	Low–Moderate
Zwierz et al., 2025 [32]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Kroon et al., 2023 [33]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Leonard et al., 2021 [34]	Moderate	Moderate	Low	Low	Moderate	Moderate	Low	Moderate
Sorour et al., 2018 [35]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Sahli-Vivicorsi et al., 2022 [16]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Yung et al., 2011 [36]	Serious	Moderate	Low	Low	Moderate	Moderate	Low	Moderate–Serious
Minoda et al., 2007 [37]	Serious	Moderate	Low	Low	Moderate	Moderate	Low	Moderate–Serious
Yanagihara et al., 2009 [38]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Vos et al., 2017 [23]	Moderate	Low	Low	Low	Low	Low	Low

Table 2. Risk of bias assessment of included studies using the ROBINS-I.

Study (First Author, Year)	Confounding	Selection of Participants	Classification of Intervention	Deviations from Intended Intervention	Missing Data	Outcome Measurement	Selective Reporting	Overall Risk
Hashmi et al., 2025 [28]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Liu et al., 2025 [29]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Chomarat et al., 2025 [30]	Moderate	Moderate	Low	Low	Moderate	Moderate	Low	Moderate
Kroon et al., 2025 [31]	Moderate	Low	Low	Low	Low	Moderate	Low	Low–Moderate
Zwierz et al., 2025 [32]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Kroon et al., 2023 [33]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Leonard et al., 2021 [34]	Moderate	Moderate	Low	Low	Moderate	Moderate	Low	Moderate
Sorour et al., 2018 [35]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Sahli-Vivicorsi et al., 2022 [16]	Moderate	Low	Low	Low	Low	Low	Low	Low–Moderate
Yung et al., 2011 [36]	Serious	Moderate	Low	Low	Moderate	Moderate	Low	Moderate–Serious
Minoda et al., 2007 [37]	Serious	Moderate	Low	Low	Moderate	Moderate	Low	Moderate–Serious
Yanagihara et al., 2009 [38]	Moderate	Moderate	Low	Low	Low	Moderate	Low	Moderate
Vos et al., 2017 [23]	Moderate	Low	Low	Low	Low	Low	Low

Table 3. Risk of bias summary of included studies assessed using the ROBINS-I tool. Green indicates low risk, yellow indicates moderate risk, and red indicates serious risk of bias.

Bias Domain	Low Risk	Moderate Risk	Serious Risk
Confounding	0	11	2
Participant selection	6	7	0
Intervention classification	13	0	0
Deviations from intervention	13	0	0
Missing data	9	4	0
Outcome measurement	5	8	0
Selective reporting	13	0	0

Table 3. Risk of bias summary of included studies assessed using the ROBINS-I tool. Green indicates low risk, yellow indicates moderate risk, and red indicates serious risk of bias.

Bias Domain	Low Risk	Moderate Risk	Serious Risk
Confounding	0	11	2
Participant selection	6	7	0
Intervention classification	13	0	0
Deviations from intervention	13	0	0
Missing data	9	4	0
Outcome measurement	5	8	0
Selective reporting	13	0	0

4. Discussion

4.1. Bioceramic Materials and Limitations

This systematic review highlights a paradigm shift in otologic surgery toward biologically active materials that support tissue regeneration. Compared to autologous materials, bioceramic scaffolds provide consistent structural support and excellent integration, particularly when combined with regenerative agents. HA remains the most widely studied and clinically implemented, with predictable outcomes in both volume preservation and patient tolerance.

Mastoid obliteration using bioceramic materials has evolved from a simple cavity-filling technique to a biologically driven reconstructive strategy. While BAG and HA-based materials provide excellent osteoconductive scaffolding and long-term volume stability, postoperative complications such as delayed epithelialization, granulation tissue formation, and material exposure remain clinically relevant. These complications are frequently related to limited vascularization and delayed biological integration of the obliterated mastoid cavity.

The overall methodological quality of the available literature was acceptable, although limited by observational designs. Importantly, no study demonstrated a critical risk of bias, supporting the reliability of the reported safety and efficacy outcomes of bioceramic mastoid obliteration.

Limitations of this review include the predominance of observational studies, heterogeneity in surgical techniques, and inconsistent outcome reporting. Long-term, prospective comparative studies with standardized definitions are required to establish optimal material selection.

4.2. Future Direction

HA-based bioceramics demonstrate slower osteoconductive remodeling compared with BAG, which may contribute to delayed epithelialization. Application of synthetic and natural hydrogel scaffolds for bone tissue engineering that are motivated by the biology and structure of the extracellular matrix (ECM).

Emerging tissue engineering strategies integrating bioceramic scaffolds with biological adjuncts such as platelet-rich plasma, bone morphogenetic proteins, and mesenchymal stem cells show promise in accelerating osteogenesis and epithelialization. However, these approaches remain largely experimental in otologic surgery. The integration of growth factors and stem cells into scaffold design represents a key advancement. Recombinant human bone morphogenetic protein-2 (rhBMP-2) and mesenchymal stem cells (MSCs) are widely studied in orthopedic and craniofacial applications for enhancing osteogenesis. When applied to otologic surgery, these agents show promise in accelerating healing and reducing fibrosis within the obliterated cavity [15,39,40] (Table 4, Figure 2 and Figure 3).

Table 4. Tissue engineering strategies for bioceramic mastoid obliteration.

Component	Example	Biological Role	Expected Benefit
Scaffold	BAG (S53P4)	Osteoconduction, antibacterial	Volume stability, infection control
Growth factor	BMP-2	Osteoinduction	Accelerated bone regeneration
Platelet product	PRP	Angiogenesis, healing	Reduced early complications
Cells	MSCs	Osteogenic differentiation	True bone regeneration

BMP-2: bone morphogenic protein-2, PRP: platelet-rich plasma, MSCs: mesenchymal stem cells.

Table 4. Tissue engineering strategies for bioceramic mastoid obliteration.

Component	Example	Biological Role	Expected Benefit
Scaffold	BAG (S53P4)	Osteoconduction, antibacterial	Volume stability, infection control
Growth factor	BMP-2	Osteoinduction	Accelerated bone regeneration
Platelet product	PRP	Angiogenesis, healing	Reduced early complications
Cells	MSCs	Osteogenic differentiation	True bone regeneration

BMP-2: bone morphogenic protein-2, PRP: platelet-rich plasma, MSCs: mesenchymal stem cells.

Platelet-rich plasma (PRP) represents a clinically feasible biological adjunct. As an autologous source of platelet-derived growth factor, vascular endothelial growth factor, and transforming growth factor-β, PRP enhances angiogenesis and soft tissue healing. PRP-augmented bioceramic obliteration may therefore reduce early postoperative complications such as persistent otorrhea and granulation tissue formation, which are among the most frequently reported minor adverse events following canal wall down mastoidectomy [41,42].

More advanced regenerative strategies incorporate mesenchymal stem cells seeded onto bioceramic scaffolds. Mesenchymal stem cells actively participate in osteogenesis and matrix remodeling, offering the potential for true biological reconstruction of the mastoid cavity [39,43,44,45,46]. Although these approaches remain largely experimental in otology, they may ultimately reduce long-term foreign-body reactions and improve radiologic interpretability during follow-up [47].

A growing area of interest is the use of custom 3D-printed scaffolds, which allow the material to conform precisely to irregular bone defects [6,40,48,49]. This level of personalization may lead to faster incorporation, lower complication rates, and better cosmetic results. Moreover, future iterations of bioceramic scaffolds may incorporate antibacterial ions, drug-eluting layers, or biosensors to monitor healing in real time. While the findings in this review are promising, most included studies were limited by small sample sizes and heterogeneity in surgical technique. Standardized outcome reporting and imaging protocols would aid in the comparison of future studies. Long-term follow-up studies are also essential to evaluate resorption rates, chronic inflammatory responses, and the durability of the scaffold in the middle ear environment.

Future clinical research should focus on prospective comparative studies evaluating bioceramic mastoid obliteration with and without biological augmentation. Standardized definitions of complications, long-term radiologic surveillance using diffusion-weighted MRI, and patient-reported outcome measures are essential to establish the true clinical value of tissue engineering-enhanced mastoid obliteration.

5. Conclusions

Bioceramic scaffolds, including HA, TCP, and BAG, are safe and effective materials for mastoid obliteration after canal wall down mastoidectomy. HA offers predictable long-term volume stability, whereas BAG provides additional antibacterial advantages. Future randomized controlled trials and standardized outcome reporting are necessary to determine material superiority and validate emerging tissue engineering approaches.