Were lateral techniques necessary in ridges with 4–5 mm of residual bone?
Tooth loss in the posterior maxilla is often associated with bone resorption and maxillary sinus pneumatisation, which limits the availability of bone for implant placement. Maxillary sinus elevation via the lateral approach, initially described by Boyne and James and later refined by Tatum, became established as a predictable technique for the treatment of the atrophic posterior maxilla. Numerous clinical studies and systematic reviews have reported implant survival rates exceeding 90%, even in situations of severe bone atrophy. These results contributed to establishing the lateral approach as the therapeutic standard, particularly in cases with residual bone height below 5mm. However, this paradigm developed in a context in which available alternatives were limited, especially regarding implant length and their biomechanical behavior.
For decades, this type of procedure has been widely used for posterior maxillary atrophy in various clinical scenarios. Nevertheless, advances in implant design and surgical techniques have progressively modified this approach. In particular, the introduction of short and extra-short implants, together with improvements in transcrestal sinus elevation techniques, has opened new, less invasive therapeutic possibilities. This evolution raises an important question regarding the relevance of lateral sinus elevation in cases with residual bone heights of 4–5mm. Today, with the availability of extra-short implants, such procedures are no longer justified from the standpoint of patient morbidity. However, a key question that arises in retrospect is whether they were truly indicated at the time. Despite its high predictability, the lateral approach is not without drawbacks. It is a more invasive surgical technique, associated with increased morbidity, longer operative time, and a non-negligible risk of complications, such as sinus membrane perforation or postoperative infections. Naturally, reflecting from the perspective of current knowledge, techniques, and available resources leads to a different interpretation, as it is important to consider that the indication of this technique in ridges with moderate residual bone height may have been influenced more by technological limitations than by strict biological necessity. In other words, the objective of achieving greater implant lengths may have driven the selection of more invasive procedures.
The present article reviews the evolution of maxillary sinus management over time and proposes a reflection on the traditional indications of the lateral approach. Considering current evidence and clinical experience, it questions whether certain procedures considered standard in the past were truly necessary or rather a consequence of the technological limitations of the time. The aim is to contribute to a more conservative implantology, grounded in biological principles and oriented toward minimising invasiveness without compromising clinical outcomes.
Materials and Methods
The present study is designed as a narrative review with a reflective component, based on the integration of available scientific evidence and accumulated clinical experience in the treatment of the atrophic posterior maxilla.
A bibliographic search was conducted in the PubMed/MEDLINE database to identify relevant studies on maxillary sinus elevation via lateral and transcrestal approaches, as well as on the use of short and extra-short implants in the posterior maxilla. The search included articles published up to 2025 and was limited to studies in humans and in the English language.
Combinations of the following MeSH terms and keywords were used: “sinus floor elevation”, “lateral sinus lift”, “transcrestal sinus elevation”, “osteotome sinus floor elevation”, “short implants”, “extra-short implants”, “posterior maxilla”, and “residual bone height”.
Systematic reviews, meta-analyses, clinical trials, and longitudinal studies with a minimum follow-up of one year were included. In addition, widely cited classical studies that contributed to the historical development of these techniques were considered in order to contextualise the evolution of the therapeutic paradigm.
Article selection was performed in a directed manner, prioritising those with the highest level of evidence and clinical relevance. The extracted information was organised according to the main axes of the study: historical evolution of the lateral approach, associated limitations and complications, evidence on short and extra-short implants, development of transcrestal techniques, and comparative studies between different therapeutic strategies.
Additionally, the analysis was complemented by the authors’ clinical experience in oral implantology, incorporating a critical perspective oriented toward decision-making in daily clinical practice. This approach allowed not only the synthesis of the available evidence, but also its reinterpretation considering current technological and biological advances.
Given the narrative and reflective nature of the study, no formal statistical analysis or systematic assessment of risk of bias was performed. However, rigorous criteria were applied in the selection and discussion of the literature, with the aim of providing a balanced and clinically relevant overview of the topic.
Results
The analysed literature shows a high predictability of the different therapeutic strategies used in the atrophic posterior maxilla, although with relevant differences in terms of invasiveness, complications, and the actual need for bone augmentation procedures.
Results of the lateral maxillary sinus approach
Sinus elevation via the lateral approach has consistently demonstrated high implant survival rates. In a classical systematic review, Wallace and Froum reported survival rates exceeding 90% with follow-ups of up to three years. Subsequently, Del Fabbro et al., in a meta-analysis including more than 6,000 implants, observed a cumulative survival rate of 91.8% at three years and 90.1% at five years. More recent studies have confirmed these long-term outcomes, with survival rates ranging from 90% to 96% in follow-ups exceeding 10 years. However, these rates are associated with a non-negligible incidence of intraoperative and postoperative complications. Sinus membrane perforation is reported in approximately 10–35% of cases, while postoperative complications (infection, sinusitis, graft failure) range between 2% and 5%.
Results of short and extra-short implants
The use of short implants has been extensively studied in recent years. In the meta-analysis by Lemos et al., which included more than 3,000 short implants, a survival rate of 96.2% was reported, with no significant differences compared to conventional-length implants placed after sinus elevation. Similarly, Thoma et al., in a multicenter trial, reported survival rates above 95% for implants ≤6 mm, with significantly lower complication rates compared to bone augmentation procedures. In randomised clinical trials, such as that by Felice et al., no statistically significant differences in implant survival were found between short implants placed in residual bone and those placed after lateral sinus elevation.
Results of transcrestal sinus elevation
Transcrestal sinus elevation has also shown favorable outcomes. In a Cochrane review, Esposito et al. concluded that transcrestal techniques allow implant placement with survival rates exceeding 90% in follow-ups of up to five years. More recently, Stacchi et al. reported survival rates of 96–98% when transcrestal elevation is combined with reduced-length implants, even in situations with limited residual bone height. The incidence of complications in these procedures is lower than that reported for the lateral approach, with membrane perforation rates generally below 5%.
Comparison between techniques
Comparative studies are difficult to interpret, mainly due to the heterogeneity of the techniques and procedures employed, as well as the different loading and drilling protocols that may influence the outcome. In systematic reviews and clinical trials, no significant differences in survival have been found between short implants placed in residual bone and those placed after lateral sinus elevation procedures. However, differences are observed in terms of morbidity, surgical time, and complications. Bone augmentation procedures, particularly the lateral approach, show higher rates of adverse events, longer treatment duration, and greater patient impact (Figure 1).
Results in relation to residual bone height
Regarding residual bone height, several studies have shown that short implants can be predictably placed in ridges with 4–5 mm of bone, achieving primary stability and high survival rates. Different studies report implant survival rates between 97–99% for short implants placed in the atrophic posterior maxilla without lateral elevation, with transcrestal elevation, or with direct placement without adjunctive techniques. Here again, there is a heterogeneous group in terms of lengths, diameters, techniques, and procedures, making it difficult to unify the results to obtain a consensus value. Additionally, favorable outcomes with high survival rates have been reported in situations with less than 5mm of residual height, which was initially considered a threshold for rehabilitation using transcrestal elevation, mainly due to the challenge of achieving three-dimensional primary stability (influenced by different implant designs and drilling and placement techniques).
These findings allow for an additional consideration from a clinical perspective. Although the lateral approach has proven to be an effective and predictable technique, current evidence suggests that, in certain scenarios with moderate residual bone height, its indication may not have been essential. In this regard, it is reasonable to consider that some cases historically treated with lateral sinus elevation – particularly in ridges with 4–5mm of residual bone – could have been managed using less invasive techniques, such as short implants or transcrestal elevation, without compromising clinical outcomes (Figures 2–16). This approach, in addition to being supported by clinical experience, is reinforced by comparative studies and clinical trials that have not demonstrated significant differences in implant survival between both approaches but have shown greater morbidity associated with bone augmentation procedures, as discussed in each of the previous sections.
Figures 2–17 show two cases performed using different approaches among those discussed in the present review.
Discussion
The analysed results confirm that both maxillary sinus elevation via the lateral approach and less invasive strategies, including the use of short implants and transcrestal elevation, can achieve high and comparable survival rates of implants placed in the atrophic posterior maxilla. However, beyond the predictability of these techniques, the available data invites a deeper reflection on the actual indication of bone augmentation procedures in certain clinical scenarios.
The lateral approach has historically been considered the therapeutic standard in situations of limited residual bone height, especially below 5mm. This position has been supported by solid and reproducible clinical outcomes over time. Nevertheless, this paradigm developed in a context in which implant length was considered a determining factor for success, and in which the available alternatives were limited. Current evidence has substantially modified this perspective. Today, it is possible to achieve adequate primary stability of implants in situations of bone atrophy (2–4mm) through drilling protocols and implant morphology; therefore, performing a regenerative procedure to place a longer implant is becoming increasingly less common. Several meta-analyses have demonstrated that short and extra-short implants present survival rates comparable to those of longer implants placed after sinus elevation, even in the posterior maxilla. Moreover, these strategies are associated with lower morbidity, shorter treatment time, and a significant reduction in postoperative complications.
In this context, it is pertinent to reconsider the indication of the lateral approach in ridges with residual bone height of 3–5mm. The available data suggests that, in many of these cases, equivalent clinical outcomes can be achieved using fewer invasive approaches. This raises the possibility that some of the classical indications for the lateral approach may not have responded to a strict biological necessity, but rather to the technological limitations existing at the time when these protocols were established.
This reinterpretation does not imply questioning the validity of the lateral approach but rather contextualising its use. In fact, it remains an essential technique in situations of severe atrophy (with 1–2mm of residual height) or when it is not possible to achieve primary stability through other planning strategies or techniques. However, its application in scenarios of moderate atrophy should be reevaluated considering current evidence. From a biological perspective, this shift in approach is also consistent. Less invasive techniques allow preservation of the existing residual bone, reducing the need for more aggressive regenerative procedures. In this sense, treatment is oriented not only toward achieving functional rehabilitation, but also toward doing so while respecting tissues to a greater extent and minimising surgical impact, thereby facilitating potential retreatments in the future if necessary.
This data should be considered. However, this study presents limitations inherent to its design. As a narrative review with a reflective component, no systematic assessment of risk of bias or formal quantitative analysis of the data was performed. In addition, the heterogeneity of the included studies may influence the interpretation of the results. Despite this, studies with a high level of evidence and clinical relevance were selected, allowing for a well-founded overview of the topic.
Conclusions
Overall, the available evidence supports a paradigm shift in the management of the atrophic posterior maxilla. Rather than replacing one technique with another, this shift involves adapting indications toward more conservative approaches, in which the use of invasive procedures is reserved for situations in which they truly provide an additional clinical benefit.
From this perspective, contemporary implantology tends toward a more individualised practice, in which treatment selection is not based solely on established protocols, but on a critical evaluation of the evidence and the optimisation of the balance between efficacy and morbidity.
References available on request.
