Primary and secondary stability in implants placed in low-density bone using conventional vs. osseodensification technique: a systematic review and meta-analysis

Abstract

Background

One of the most important clinical challenges in implant dentistry is achieving stability in low-density bone. Identifying a method that maximizes implant stability in bones of low quantity and quality is crucial. Osseodensification (OD) has been suggested as an alternative to conventional drilling (CD) to improve implant stability. This study compared the primary and secondary stability of two commonly used techniques for implant placement in low-density bone: CD and OD.

Methods

Search was conducted in PubMed, Scopus, Web of Science, EMBASE, and Google Scholar up to January 2024. Studies that evaluated dental implant placement in low-density bone using the OD technique and compared it with CD were included in this study. These studies assessed primary and secondary stability using the Implant Stability Quotient (ISQ). Additionally, other outcomes such as marginal bone loss (MBL), crestal bone level (CBL), probing depth (PD), and plaque index (PI) were analyzed. The meta-analysis was conducted using a random-effects model and presented as overall mean differences along with 95% confidence intervals (CIs) and p-values for each outcome. Subgroup analyses were also performed for a few outcomes, primarily by follow-up time or anatomical site of intervention. The Comprehensive Meta-Analysis software, version 2, was used for all analyses.

Results

Seven studies met the inclusion criteria. The follow-up periods varied across studies and included 4, 6, 8, and 12 months. There are no statistically significant differences between OD and CD groups in primary stability (MD = 4.13, P = 0.13) or secondary stability (MD = 1.78, P = 0.11). No significant differences were found in MBL and PI. However, for PD, the OD group showed a significantly lower PD at 12 months. In the CBL outcome, a significant difference in favor of OD was observed only at the palatal site.

Conclusion

There is not enough strong evidence to say that OD is better than CD in the long term. More randomized clinical trials (RCTs) with standardized protocols and longer follow-up periods are recommended. Additional long-term, well-designed comparative human studies are needed to declare the advantages and disadvantages of the OD technique vs. the CD technique. There was some heterogeneity across sites, gender, duration of follow-up, implant system, and operator, but not affect the comparability and generalizability of this meta-analysis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-025-07201-w.

Introduction

Dental implants are currently considered one of the most effective methods for replacing missing teeth [1]. Implant success depends on achieving both primary and secondary stability, especially in patients with low-density bone [2, 3]. Primary stability arises from the mechanical interaction between the implant and the bone walls immediately after placement [4], while secondary stability refers to long-term biological process of osseointegration, whereby bone forms a direct interface with the implant surface. Secondary stability is absent at the time of implant placement and develops progressively over time [3].

Primary stability depends on various factors, including bone quality and density, implant morphological characteristics such as surface treatment, and an atraumatic surgical technique used for placement [4]. Among these factors, achieving adequate stability in low-density bone, commonly encountered in the posterior maxillary and mandibular, is particularly challenging due to reduced bone density, increased porosity, and diminished mechanical strength [5]. Poor primary implant stability can lead to micromovement, which negatively affects osseointegration [6]. Therefore, optimizing implant stability in these regions is crucial to the long-term success and survival of dental implants [7]. Consequently, osteotomy site preparation for dental implant placement is a critical step in implant surgical procedures and affects implant survival [4].

The CD method typically involves osteotomy site preparation using a stepped series of cylindrical or tapered drills that cut and remove bone tissue in a clockwise rotation before implant placement [8]. This method is widely used because it is simple, time-efficient, and cost-effective [9]. However, the heat generated during this process may cause tissue injury and necrosis of surrounding structures, complicate proper three-dimensional positioning, and increase risk of damage to important anatomical structures such as the inferior alveolar nerve and the Schneiderian membrane [9, 10]. Additionally, severe bone compression may lead to ischemia, raising concerns about secondary stability [11].

In contrast, the OD technique is a newer approach that uses single-fluted Densah burs operated counterclockwise at 800–1500 rpm to compact and densify bone during site preparation, rather than simply removing bone. This technique is believed to improve both primary stability by increasing bone-implant contact and secondary stability by stimulating bone formation around the implant [8, 12, 13]. Although bone can withstand some mechanical strain, overloading may initiate microcracks that lead to interfacial remodeling and eventual MBL. Excessive insertion torque poses an additional risk by compressing the bone, reducing its blood supply, and increasing the risk of failed osseointegration [14]. Several studies have indicated that OD may offer superior results in terms of implant stability, particularly in low-density bone, although findings have varied across clinical settings [15].

Despite growing interest in OD as an alternative to the CD technique, the comparative efficacy of these methods for primary and secondary stability remains unclear. While some studies suggest that OD may enhance initial stability and promote favorable bone healing, others report no significant differences in long-term osseointegration outcomes [16, 17].

Given these conflicting findings, a systematic review and meta-analysis is warranted to synthesize available data and provide a clearer understanding of the relative benefits of CD compared with OD for implant placement in low-density bone. These discrepancies can be explained by differences in study design (RCT vs. clinical trials), the metrics used to quantify stability (insertion torque vs. resonance frequency analysis), variability in implant macrogeometry and bur design, definitions of “low-density bone,” sample sizes, and differences in operator experience and follow-up duration. This systematic review and meta-analysis aimed to compare the effectiveness of CD and OD in achieving primary and secondary stability of dental implants placed in low-density bone (bone types III and IV). By analyzing data from multiple studies, this review seeks to provide an evidence-based understanding of how these techniques perform across comparable clinical conditions, with the ultimate goal of guiding clinical decision-making and improving outcomes for patients requiring implants in challenging bone types.

Methods

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist [18].

Research question and PICO framework

The structured research question guiding this systematic review was: “In patients requiring dental implants in low-density bone, does the OD technique provide superior primary and secondary stability compared with CD techniques?”

The PICO framework used to guide this review was:

• Population (P): Patients requiring dental implants in low-density bone (bone types III and IV).

• Intervention (I): Osseodensification (OD) drilling technique for implant site preparation.

• Comparison (C): Conventional drilling (CD) technique for implant site preparation.

• Outcomes (O): Primary outcomes: Primary stability, secondary stability; Secondary outcomes: marginal bone loss (MBL), crestal bone level (CBL), probing depth (PD), and plaque index (PI).

Inclusion and exclusion criteria

The inclusion and exclusion criteria are described in Table 1:

Table 1.

Inclusion and exclusion criteria

Criterion	Inclusion	Exclusion
Study types	Original comparative clinical studies	Reviews, in vitro studies, studies without full-text access, academic theses
Population	Patients requiring implants in low-density bone (type III or IV)	Patients with systemic diseases or conditions
Intervention	Osseodensification drilling	Techniques other than osseodensification
Comparator	Conventional drilling	Studies without conventional drilling as comparator
Outcomes	Primary and secondary stability (ISQ)	Studies not reporting these outcomes
Follow-up duration	Minimum 3 months follow-up	Less than 3 months follow-up
Language	English	Non-English publications

Search strategy

A comprehensive search was conducted across PubMed, Web of Science (ISI), Scopus, EMBASE, and Google Scholar through January 2024. Key search terms were combined using the Boolean operators (“AND”, “OR”) to identify relevant studies. For PubMed, the full search string was:

(“osseodensification” OR “osseodensification drilling”) AND (“conventional drilling” OR “traditional drilling” OR “standard drilling”) AND (“primary stability” OR “secondary stability” OR “implant stability”).

The number of records initially retrieved from each database are reported below:

The initial search retrieved a total of 97 records from PubMed, 379 records from Web of Science (ISI), 94 records from Scopus, 88 records from EMBASE, and approximately 1,010 records from Google Scholar, of which only the first 100 records were screened.

Study selection process

All studies were imported into EndNote software (version 21.2) for organization. After duplicates were removed, two reviewers independently screened titles and abstracts to assess study eligibility against the inclusion and exclusion criteria. Full texts articles of potentially relevant studies were then assessed in detail. Any disagreements were resolved by consensus; a third reviewer adjudicated when necessary.

Data extraction

Data extraction was performed manually and independently by two reviewers using a self-designed data extraction form. Extracted data included the following variables: authors, publication year, study design, country, type of intervention, comparison group, total sample size, sample size in intervention and comparison groups, follow-up period, and outcomes measured.

All extracted data were organized in Microsoft Excel software. Any disagreements between reviewers were resolved through discussion to reach a consensus.

Quality appraisal

In this review, one reviewer screened all included studies independently, and a second reviewer then checked the scoring. Any disagreements in scoring were resolved through discussion and consensus.

RCT studies were evaluated with the ROB 2 tool [19]. ROB 2 covers five domains (bias arising from the randomization process, deviations from intended interventions, missing outcome data, outcome measurement, and selective reporting). Each domain, and the trial as a whole, is rated “low risk,” “some concerns,” or “high risk”.

non-RCT studies were assessed using the ROBINS-I tool, which evaluates risk of bias across seven domains: D1 (confounding), D2 (selection of participants), D3 (classification of interventions), D4 (deviations from intended interventions), D5 (missing data), D6 (measurement of outcomes), and D7 (selection of the reported result) [20]. For each domain and for the overall study, risk of bias is rated as “low,” “moderate,” “serious,” “critical,” or “no information (NI)”.

By combining ROB 2, and ROBINS-I, we applied design-specific, state-of-the-art instruments to ensure that the quality and credibility of every included study were critically evaluated.

Data analysis and synthesis

Comprehensive Meta-Analysis (CMA) software, version 3, was used for data analysis. Meta-analysis was conducted using a random-effects model given the high between studies heterogeneity Extracted data included means and standard deviations for the desired outcomes. I² values were calculated to assess statistical heterogeneity. Results were expressed as overall mean differences with 95% confidence intervals (CIs) and p values for each outcome. Subgroup analyses were also performed for selected outcomes, primarily by follow-up duration or anatomical site.

Results

Study selection

The search identified a total of 758 records via database searches, which were imported into EndNote software. After removing 417 duplicate records, 341 records remained for screened.

Following screening, 332 records were excluded after title and abstract review as not relevant to the research question. In the second phase, the full texts of the remaining 9 articles were assessed for eligibility. Two articles were excluded at this stage: one in vitro study and one study with irrelevant data [21, 22].

Finally, 7 studies met the inclusion criteria and were included in the final review [11, 23–28]. The PRISMA flow diagram of study selection is presented in Fig. 1.

Fig. 1.

Search process and study flow-diagram

Characteristics of included studies

The characteristics of the included studies are presented in Table 2. A total of seven studies published between 2020 and 2024, were included in this review. All included studies compared the OD with the CD techniques.

Table 2.

Summary characteristics of included study

Author, year	Study design	country	Intervention group	Comparison group	Sample size	Follow up period	Outcome(s)
Sultana, A., et al [23] 2020	non-randomized clinical trial	India	OD	CD	20 implants Group OD: 10 implants Group CD: 10 implants	Baseline, 6, 8 months	- The primary stability: in OD drills was slightly higher than with CD with no statistical significance difference (P > 0.05). - No significant difference between the two groups in terms of crestal bone levels (P > 0.05).
Rashmi [28] 2022	nonRCT	India.	OD	CD	20 implants Group OD: 10 implants Group CD: 10 implants	Baseline, 4, 6, 8 months	- No statistically significant difference in implant stability between the CD and OD drilling (P > 0.05). - No significant difference between the two groups in terms of crestal bone levels (P > 0.05).
Atef, M., et al. [26] (2021)	Prospective, observational study	Egypt	OD	CD	Seven females Group OD: 7 implants in one side Group CD: 7 implants on the other side	Baseline, 6, 7, 12 months	- No valuable difference existed between the two groups regarding primary and secondary stability, PI, bleeding on probing, PD, and MBL. - Statistically significant difference was seen in bone density in favor of OD group immediately after surgery
Shanmugam, M., et al. [11] (2024)	A Prospective RCT	India	OD	CD	30 participants Group OD: 15 participants Group CD: 15 participants	Baseline, 3, 6 months	- OD impacted the width at the apex (5 mm from the crest) and radiographic bone density. - OD did not affect implant stability and crestal width after osseointegration. - The mean difference of crestal width in CD and OD groups was 0.46 and 0.68 mm, respectively. - The mean difference of width at the apex (5 mm from the crest) was 0.74 and 0.58 mm for CD and OD groups, respectively.
Singh, I., et al. [24] (2022)	randomized clinical trial	India	OD	CD	24 patients Group OD: 12 patients Group CD: 12 patients	Baseline, 3, 6 months	- In OD group, the ISQ values at the time of placement, three months, and six months after implant placement showed a statistically significant difference - The difference in the ISQ values in CD group was not significant
Punnoose, K., et al. [25] (2022)	Prospective, observational study	India	OD	CD	13 patients Group OD: 13 implants Group CD: 13 implants	Baseline, 4 months	- The mean value of primary implant stability in OD group was 74.5 vs. 62.08 in CD group (P = 0.001). - The mean value of secondary implant stability in OD group after 4 months’ interval was 70.92 vs. 63.69 in CD group (P = 0.001).
Al Ahmari, N. M. [27] (2022)	non-randomized clinical comparative studies	Saudi Arabia	OD	CD	20 patients, 40 implants Group OD: 20 implants Group CD: 20 implants	Baseline, 7, 12 months	Immediately after surgery: - Bone density was statistically significant in favor of the OD group. - Primary and secondary stability, PI, bleeding on probe, PD, and even MBL were not significantly different between the two groups.

OD Osseodensification, CD Conventional drilling, marginal bone loss, MBL Probing depth, PD and plaque index, PI Implant Stability Quotient; ISQ

*RCT, Randomized controlled trial

Most studies were conducted in India, with additional studies taking place in Saudi Arabia and Egypt. The number of implants ranged from 14 to 40, while the number of patients ranged from 7 to 30. There was an approximately equal allocation between intervention and control groups.

All included studies evaluated the relationship between implant stability and the implant site preparation technique.

For example, Sultana et al. and Rashmi et al. found no statistically significant differences in implant stability or CBL changes between the OD and CD groups after 8 months of follow-up [23, 28].

Conversely, Shanmugam et al. reported an immediate increase in bone density following OD, although this improvement did not significantly affect implant stability or crestal width after 6 months [11].

Similarly, Singh et al. observed a significant increase in ISQ values favoring the OD group at placement and at 3 and 6 months postoperatively [24].

Punnoose et al. also demonstrated that the OD group exhibited significantly greater primary and secondary implant stability compared than the CD group (P = 0.001) [25].

However, Al Ahmari et al. found no difference between the two groups in terms of implant stability, PI, bleeding on probing, or MBL, although bone density during the immediate postoperatively phase was greater in the OD group [27].

Similarly, Atef et al. reported no statistically significant differences in primary and secondary implant stability between the two groups after 12 months of follow-up [26].

Quality assessment

Two randomized controlled trials were assessed using the ROB 2 tool, and five non-RCT studies were evaluated with the ROBINS-I tool. None of the included studies were excluded after the quality assessment.

For the RCTs, the overall ROB 2 judgment was “some concerns,” mainly due to issues in the randomization process (Domain 1), potential deviations from intended interventions (Domain 2), and possible bias in outcome measurement (Domain 5). Other domains were considered at low risk [11, 24].

The five studies evaluated with the ROBINS-I checklist were judged to have an overall moderate risk of bias. The main reason for this rating was the presence of concerns in Domain 1 (confounding), which was assessed as moderate in all included studies. In addition, one study received a moderate rating in Domain 3 (classification of interventions), another in Domain 6 (measurement of outcomes), and one more in Domain 7 (selection of the reported result) [23, 25–28].

A summary of the quality assessment scores of all included studies is presented in Fig. 2A-D and Supplementary File 1.

Fig. 2.

A: Traffic light plot of the ROBINS-I checklist B: Traffic light plot of the ROB 2 checklist. C: Summary plot of the ROBINS-I checklist, used to assess the observational studies. D: Summary plot of the ROB 2 checklist, used to assess the RCT

Meta-Analysis results

In total, meta-analysis was included for six outcomes, summarized as follows:

RFA1 (resonance frequency analysis shows primary or baseline Stability)

All included studies [11, 23–28] reported this outcome at the time of implant placement. Meta-analysis showed no statistically significant difference between OD and CD (MD = 4.13, 95% CI: −1.19 to 9.45, P = 0.13), with high heterogeneity (I² = 77%). Results are shown in Fig. 3.

Fig. 3.

Forest plot of comparison of RFA1 of the osseodensification drilling and conventional drilling

RFA2 (shows follow-up or secondary Stability)

This outcome was reported in all studies [11, 23–28] at various time intervals; therefore, subgroup analysis was performed according to the reported time intervals, which included 3, 4, 6, and 7 months (MD = 1.78, 95% CI: −0.40 to 3.96, P = 0.11), with high heterogeneity (I² = 61%). No significant difference was observed at any interval except at 4 months, which slightly favored OD (MD = 7.23, P < 0.00001) [25]. Because this result derives from a single study, it should be interpreted with caution and is not generalizable. Results are shown in Fig. 4.

Fig. 4.

Forest plot of comparison of RFA 2 of the osseodensification drilling and conventional drilling across different follow-up periods (3, 4, 6, and 7 months)

MBL

Three studies [26–28] reported this outcome at baseline and 4, 7, 8, and 12 months. Subgroup meta-analysis showed no statistically significant difference between OD and CD (MD = 0.18, 95% CI: −0.18 to 0.55, P = 0.32), with high heterogeneity (I² = 95%). At 4 months was a minor difference favoring OD noted (MD = 1.19, P < 0.00001); but this result was based on a single study and should be interpreted with caution, as it is not generalizable [28]. Results are shown in Fig. 5.

Fig. 5.

Forest plot of comparison of Marginal Bone Loss of the osseodensification drilling and conventional drilling across different follow-up periods at baseline, 4, 7, 8, and 12 months

PI

Two studies [26, 27] reported this outcome in 7 and 12 months Meta-analysis showed no statistically significant difference between OD and CD (MD = 0.01, 95% CI: −0.05 to 0.06, P = 0.82), with no heterogeneity (I² = 0%). Results are presented in Fig. 6.

Fig. 6.

Forest plot of comparison of Plaque Index of the osseodensification drilling and conventional drilling across different follow-up periods at 7 and 12 months

PD

Two studies [26, 27] reported this outcome in 7 and 12 months. Meta-analysis showed a statistically significant overall difference between OD and CD (MD =−0.25, 95% CI: −0.43 to −0.08, P = 0.005), with moderate heterogeneity (I² = 43%). In subgroup analyses by time point, the 12-month estimate favored OD (MD = −0.42, P = 0.001), whereas at 7 months no statistically significant difference was observed (MD = −0.11, P = 0.37). Given the limited number of studies, these findings should be interpreted with caution and are not generalizable. Results are presented in Fig. 7.

Fig. 7.

Forest plot of comparison of pocket depth of the osseodensification drilling and conventional drilling across different follow-up periods at 7 and 12 months

CBL

Two studies [23, 28] reported this outcome across four anatomical sites (labial–buccal, palatal, mesial, distal). Subgroup meta-analysis showed no statistically significant overall difference between OD and CD (MD =−0.37, 95% CI: −0.75 to 0.01, P = 0.06), with no heterogeneity (I² = 0%). At the palatal site, the estimate favored OD (MD = −0.67, 95% CI, P = 0.04); however, because this significance arises from a single subgroup (with a small evidence base), it should be interpreted with caution and is not generalizable. Results are shown in Fig. 8.

Fig. 8.

Forest plot of comparison of Crestal bone loss of the osseodensification drilling and conventional drilling at four anatomical sites (labial-buccal, palatal, mesial, and distal)

Discussion

The stability of dental implants is a cornerstone of their long-term success, particularly when implants are placed in low-density bone (bone types III and IV), which is commonly found in the posterior maxillary and mandibular. This systematic review and meta-analysis aimed to compare primary and secondary stability outcomes in implants placed in low-density bone using CD techniques versus the OD technique. Our findings indicate that both techniques can achieve successful outcomes, with no notable differences in their effects on primary and secondary implant stability. Furthermore, we found no clear advantage for OD compared to CD regarding MBL, PI, PD, and CBL.

Compared with recent OD versus CD reviews [29–31], our analysis is characterized by a D3–D4 low-density focus, a more extensive and current search (PubMed/MEDLINE, Embase, Scopus, Web of Science, and Google Scholar through January 2024), and a clinically focused outcome set combining ISQ at several time points (baseline, 3, 4, 6, and 7 months) with MBL, CBL, PI, and PD. We prespecified a random-effects model in Comprehensive Meta-Analysis and employed design-specific risk-of-bias tools (RoB 2 for RCTs, and ROBINS-I for nonrandomized studies). Unlike other syntheses that employed narrower databases, focused on histomorphometric surrogates, or combined human and animal evidence, we limited analyses to human clinical endpoints and performed anatomical-site subgroup analyses, providing time- and site-resolved estimates directly transferable to low-density (D3–D4) implant sites. Additional distinctions are presented in the Supplementary Materials (Supplementary File 2).

Primary stability is essential for minimizing micromotion and ensuring successful osseointegration. Inadequate primary stability can lead to micromotion exceeding the threshold for successful osseointegration (typically >50–150 μm), resulting in fibrous encapsulation and implant failure [32]. Primary stability is influenced by surgical technique, implant design, and the quality and quantity of the surrounding bone [3, 4, 33]. Several authors have postulated that the densification effect increases the mechanical strength of the surrounding bone, especially in low-density bone, thus enhancing primary stability [34]. The increased primary stability observed with OD is consistent with biomechanical models showing that bone compaction improves its mechanical properties [17]. The specialized drills used in OD create a lateral compression zone that enhances the bone’s resistance to displacement and to implant micromotion, which is a crucial factor in maintaining initial stability [21]. This process appears to be particularly beneficial in low-density bone, which is typically more prone to bone deformation and implant instability with CD methods are employed. However, combining the results in this meta-analysis did not confirm the benefits cited for the OD method. It appears that more human studies are needed to assess these results.

On the ISQ scale, values >70 denote high stability, 60–69 moderate stability, and < 60 low stability [35]. Huwiler et al. suggested that ISQ readings of 57–70 represent a stable healing phase, although they are not always predictive of subsequent loss of stability [36]. Conversely, ISQ values below 70–75 at placement or within 3–4 months are associated with a higher risk of failure [37]. When these reference thresholds are applied to this meta-analysis, both OD and CD yielded mean ISQ values that remained in the clinically acceptable range (≥ 57) from placement through 6 months of follow-up, with no sustained, statistically significant difference between techniques.

Secondary stability refers to the long-term stability achieved through osseointegration and is influenced by factors such as bone quality, implant surface characteristics, and the absence of micromotion during the healing phase [38]. Secondary stability was measured in the included studies at 3, 6, and 7 months after intervention; OD did not provide a significant advantage. A small trend favoring OD was observed at 1.5–3 months, but the data were insufficient to establish statistical significance. Only one study reported a temporary benefit of OD at 4 months [25]. The short-term gain may result from the way OD compresses the bone walls, providing the implant with higher stability. During normal bone healing, however, the initial compacted bone layer is resorbed and replaced by new bone, and the early benefit may fade [22, 25, 39, 40].

Generally, higher primary and secondary stability are expected in implants placed using the OD technique compared with the CD technique in low-density bone for three reasons:1) The primary mechanism of OD is bone compaction. In low-density bone, this compaction can lead to a denser layer of bone surrounding the implant. This increased density directly translates to greater initial mechanical interlock and thus higher primary stability, often measured by ISQ values and insertion torque [41, 42]. 2) Unlike CD techniques that remove bone and, in low-density scenarios, can further compromise the already limited bone support, OD compacts rather than removes bone, preserving existing bone volume and potentially enhancing its quality at the implant-bone interface [17]. 3) The denser bone achieved with OD may also positively influence secondary stability by providing a more favorable environment for osteoblast activity and bone apposition onto the implant surface [43].

Regarding MBL, the only exception occurred at 4 months, where Rashmi et al. (2022) reported less bone loss in the OD group [28]. This finding may suggest that initial bone resorption progresses more slowly after OD, whereas it continued in the CD group. Kitamura et al. showed that as little as 0.5 mm of crestal bone loss can increase peak peri-implant stress by approximately 25% [44]. Therefore, even small differences in MBL, such as the 4 month result, may alter load distribution and long-term stability. Clinically, improved crestal bone levels with OD could reduce the risk of early failure, but longer trials are needed to confirm this hypothesis.

In this study, there was no significant difference in the PI between the OD and CD techniques. Since reducing dental PI can be achieved through various treatment and oral-care protocols, the lack of clear information about oral hygiene protocols may affect the interpretation of results. Moreover, plaque accumulation depends on several factors, including implant material, surface topography, and microstructural features of the implant [45]. Plaque primarily accumulates at the interfaces of implant components, microgaps at the implant-abutment junction, the abutment-crown interface, and rough titanium surfaces. Increases in microgap size and surface roughness, as well as excessive restorative contours, can increase the risk of bacterial colonization and biofilm formation [46].

For PD, we observed a significant difference at 12 months favoring the OD technique, with no difference at 7 months. This late benefit is probably related to the way OD compresses the bone during drilling, rather than differences in study design. Densah burs compact the bone and push bone chips against the osteotomy walls. This preserves vital bone, increases local bone density, and provides the implant with stronger mechanical interlock. Because less bone is removed, the healing phase before final crown placement can be shorter. A shorter healing time may reduce inflammation, limit bone loss, and ultimately lead to shallower PD [23, 41]. Other risk factors such as smoking, poor oral hygiene, history of periodontitis, and lack of professional maintenance can also increase the likelihood of peri-implant disease and affect PD [47]. Additionally, both studies reporting PD were conducted in the lateral maxilla, and did not loading protocols. Therefore, we must be cautious before applying these results to other jaw areas or to immediate-loading situations. Variability in implant systems, surgical protocols, and bone-measurement methods may further limit data consistency, although statistical heterogeneity in this subgroup was low.

When combining all four sites (labial-buccal, palatal, mesial, and distal), there was no significant difference between OD and CD techniques. A clear advantage appeared only on the palatal side, where OD demonstrated less bone loss. This local benefit is probably linked to the way OD presses bone chips against the inner wall of the osteotomy, creating a denser palatal plate that resists early resorption. On the buccal side, where the cortical plate is thinner, both techniques performed similarly. Overall, OD neither harms nor clearly improves crestal bone levels under normal clinical conditions. Different healing patterns may also play a role. With OD, a thin buccal layer of bone is usually preserved, while CD often leaves a small buccal dehiscence. The remaining bone layer, together with the autogenous chips packed by the Densah bur, can accelerate revascularization and new bone growth. Maiorana et al. reported a similar effect when they used Bio-Oss to maintain the crestal contour and reduce natural resorption. Because bone graft particles in the OD site act as a scaffold, denser bone may form more quickly than in CD, where graft resorption takes longer and healing is slower [48].

This systematic review and meta-analysis has several limitations. First, the search was limited to studies published in English, which may have introduced publication bias and excluded other relevant research published in other languages.

Second, there was substantial heterogeneity among the included studies. Contributing factors likely include disparate implant macrogeometry, drilling speeds, follow-up periods (3–12 months), and small sample sizes (7–30 patients). Because of these differences, any advantage or disadvantage of the OD technique should be interpreted with caution until standardized protocols are tested in larger RCTs with ≥ 24 month endpoints.

Third, all studies were conducted in India, Saudi Arabia, or Egypt, which limits global generalizability given potential differences in bone density, dietary habits, and treatment protocols. Thus, generalizing these findings to other geographic regions or populations should be done cautiously, and future studies from other countries are recommended to confirm the global applicability of these results.

Fourth, although no study was excluded after quality appraisal, the overall methodological quality was only fair. The two RCTs was rated “some concerns” in the ROB 2 tool, owing to weaknesses in the randomization process and possible deviations from the intended protocol.

These limitations highlight the need for well-powered, rigorously designed RCTs that use a uniform implant design and drilling protocol, incorporate proper blinding, ensure transparent reporting of randomization and calibration procedures, and extend follow-up to at least 24 months. Such trials would provide a stronger evidence base for clinical decision-making.

Conclusions

This review indicates that OD and CD provide comparable outcomes for implant placement in D3-D4 bone and may therefore be considered safe alternatives. However, this equivalence is based on low certainty evidence from small, heterogeneous studies with ≤ 12 months of follow-up and moderate risk of bias. Because OD requires single-use densifying burs, specialized handpieces, and a steeper learning curve, its routine adoption cannot yet be justified until cost-effectiveness is demonstrated. Adequately powered, RCTs should: (i) apply standardized surgical protocols and double-blind outcome assessment, (ii) include economic endpoints such as instrument cost and chair time, (iii) stratify results by anatomical region as well as bone density, and (iv) report ≥ 24 months of follow-up. Until such data is available, OD should be regarded as a context-specific option rather than a demonstrably superior technique.

Abbreviations

OD

Osseodensification

CD

Conventional drilling

ISQ

Implant stability quotient

MBL

Marginal bone loss

CBL

Crestal bone level

PD

Probing depth

PI

Plaque index

PRISMA

Preferred Reporting Items for Systematic Reviews and Meta-Analyses

RCTs

Randomized clinical trials

MD

Mean difference

CIs

Confidence intervals

Authors’ contributions

Concept development of the study and title design were carried out by MM-M and MM. The methodology, design, and supervision of the systematic review and meta-analysis process were conducted by MA-Z. Database search was conducted by MA-Z, and study selection and data extraction were carried out by MM-M and MM. The quality of included studies was evaluated by MA-Z and MM. Statistical analysis was performed by MA-Z. The first draft of the manuscript was prepared by MM. All authors contributed to the revision and final editing of the manuscript and approved its final version.

Funding

Not applicable.

Data availability

All data generated or analysed during this study are included in this published article and its supplementary information files.

Declarations

Ethics approval and consent to participate

This article was extracted from a thesis approved by Birjand University of Medical Sciences, Birjand, Iran. This thesis received an ethical code of IR.BUMS.REC.1403.162, from Iran National Committee for Ethics in Biomedical research.

Consent for publication

Not Applicable.

Competing interests

The authors declare no competing interests.