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\begin{document}

\title{Bicortical stability of implants placed in severely atrophic posterior
maxilla; a novel technique}



\author[1]{mojtaba salehi karizmeh}%
\author[2]{Mahboube  hasheminasab}%
\author[1]{Narges Hajiani}%
\affil[1]{Tehran University of Medical Sciences}%
\affil[2]{University of the Pacific Arthur A Dugoni School of Dentistry}%


\vspace{-1em}



  
  \date{May 22, 2024}


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\selectlanguage{english}
\begin{abstract}
Simultaneous implant placement with sinus floor augmentations is
possible when appropriate primary stability could be achieved. In
current study, a novel technique is described to perform a single stage
implant placement with bicortical stability in severe atrophic maxilla
that can shorten the treatment time of an edentulous patient.%
\end{abstract}%



\sloppy


Bicortical stability of implants placed in severely atrophic posterior
maxilla; a novel technique

Abstract

Maxillary sinus lift is a common procedure to achieve adequate alveolar
bone height in patients with sinus hyper-pneumatization. Simultaneous
implant placement with sinus floor augmentations is possible when
appropriate primary stability could be achieved. In severe atrophic
posterior maxillary ridge, vertical bone height is sometimes less than 4
mm, which may hinder simultaneous implant placements and necessitate two
stage procedure. In current study, a novel technique is described to
perform a single stage implant placement with bicortical stability in
severe atrophic maxilla that can shorten the treatment time of an
edentulous patient. During the procedure, to achieve an adequate access
a conventional lateral window osteotomy is performed. After elevating
the Schneiderian membrane using conventional instruments, an autologous
ramus block is harvested from the mandible and then the block will be
fixed in correct location in the sinus using screws with appropriate
length to build sufficient stability as superior cortex for simultaneous
implant insertion.

Introduction

Implant-supported prostheses have become one of the best treatments for
edentulous patients. Significant vertical maxillary defects create a
challenging situation to rehabilitate edentulous posterior maxilla,
which is a consequence of maxillary sinus hyper-pneumatization and
long-term alveolar ridge resorption. This situation indicates a
necessity to restore the bone crest anatomy accompanying with sinus
floor elevation (1, 2). There are many surgical options using different
biomaterials of different components to reestablish an adequate bone
volume for implant placement. Most of these surgical options require
multi-staged procedures which might lead to patients' discomfort and
long treatment time specially in severely atrophic posterior maxilla
(less than 4mm residual bone)(1). In addition, the volume of the
augmented space tends to decrease during healing, especially in delayed
implant insertion. The amount of resorption also depends on types of
grafting materials used for sinus augmentation(3). Nevertheless,
intraoperative complications such as sinus membrane perforation tends to
increase in two stage surgeries. This complication may lead to
dislodgement of graft material into the sinus and graft failure (4, 5).

Today there are typically two sinus lift protocols: two-stage and
one-stage techniques. Technique selection is based on the amount of
residual bone height, which provides the initial implant stability.
Clinical evidence suggests that the minimum bone height to provide
simultaneous implant insertion is 4-5 mm (6, 7).

The aim of this study is to present a new technique that provides a good
bicortical primary stability of implants in patients with limited
residual bone height in posterior maxilla in a single stage surgery.

Surgical technique

In present study, we describe a new technique to achieve an acceptable
bicortical stability during implant insertion in severely atrophic
posterior maxillary ridge. This procedure can be performed in patients
having residual bone height between 1 to 3 mm, which is approved with
CBCT before the procedure. Patients should have no history of poor
controlled systemic disease such as diabetes and no history of sinusitis
(fig-1). During the procedure, a conventional lateral window osteotomy
is performed and adequate access to sinus cavity is achieved. Then the
Schneiderian membrane is elevated using conventional sinus lift
instruments. Future location of implants is allocated on alveolar ridge
according to the CBCT \& the exact locations are measured using
calibrated probe. After exposing the maxillary sinus, an autogenous
block graft is harvested from lateral cortex of unilateral mandibular
ramus. The block size should be compatible with the size of the bone
window and the location of implants apexes are marked on the ramus block
graft. Then the graft is placed inside the exposed sinus with its
smallest dimension and is rotated in the sinus so that it is parallel to
the alveolar bone and in the right position (fig-2). After that, the
ramus blocks are fixed in correct location using screws with appropriate
length. These screws are placed through the alveolar bone to the ramus
graft in a location other than determined locations for implants and
together with the block graft, they hold the sinus membrane elevated. In
the following step, the implants are placed in both alveolar ridge and
ramus block graft. The primary stability of implants is established by
bicortical stability, one with alveolar ridge at the crestal level of
implants and one with ramus graft at the level of implants apexes
(fig-3). Finally, the space between the two cortexes is filled with
biocompatible allograft bone materials and the lateral window is covered
using a membrane. Then the mucoperiosteal flap is sutured. After follow
up period of 30 months, all the implants are osteointegrated completely
and no obvious bone loss is observed.

Discussion

The purpose of this study is to describe a new method to perform a
single stage implant placement in atrophic posterior maxilla, with
residual bone height between 1 to 3mm. Using this method, a bicortical
primary implant stability is achieved despite the very limited amount of
crestal bone. In previous studies, different methods for atrophic
posterior maxilla reconstruction have been introduced. Allogenic
cancellous bone blocks were used for maxillary sinus floor elevation in
severely atrophic posterior maxilla but it impose a secondary stage
surgery to the patient for implant placement (8). Simultaneous implant
placement and sinus floor elevation have been performed using
leukocyte-and platelet- rich fibrin as a sole graft material (9).
Another reconstruction technique is simultaneous implant placement
concomitant with maxillary sinus floor augmentation in posterior maxilla
using mixture of bioactive glass granules and autogenous bone (10). In
another study, simultaneous porcine bone layer insertion accompanied by
graft less maxillary sinus floor augmentation has leaded to effective
bone formation (11). In all mentioned techniques, implant placement
cannot be implemented in residual bone height less than 3mm due to
inadequate primary stability.

In our presented technique, we fix the cortical bone to make it stable
enough. This way the graft can provide adequate retention and stability
for implants. In addition, bicortical primary stability achieved by
superior cortical layer eliminates the second stage of the surgery and
accelerates the healing process of patients. In addition, there is no
need to remove the bone retaining screws. Based on our experience, the
morbidity of donor site was mild and none of the patients complained of
any neurosensory changes and no significant complications such as
infection was found. Another advantage of this study is being
cost-effective by eliminating the second surgery stage.

In general, one stage implant placement at the time of sinus floor
elevation in severely atrophic posterior maxilla using cortical ramus
graft can provide a proper primary stability, which can decrease
treatment time, but a clinical trial is necessary to assess the efficacy
of this new technique.

Acknowledgments

The authors reported no conflicts of interest to this study.

References

1. Cha HS, Kim A, Nowzari H, Chang HS, Ahn KM. Simultaneous sinus lift
and implant installation: prospective study of consecutive two hundred
seventeen sinus lift and four hundred sixty-two implants. Clin Implant
Dent Relat Res 2014;16:337-347.

2. Silva LD, de Lima VN, Faverani LP, de Mendonca MR, Okamoto R,
Pellizzer EP. Maxillary sinus lift surgery-with or without graft
material? A systematic review. Int J Oral Maxillofac Surg
2016;45:1570-1576.

3. Masuda K, Silva ER, Alccayhuaman KAA, Botticelli D, Xavier SP.
Histologic and Micro-CT Analyses at Implants Placed Immediately After
Maxillary Sinus Elevation Using Large or Small Xenograft Granules: An
Experimental Study in Rabbits. Int J Oral Maxillofac Implants
2020;35:739-748.

4. Testori T, Tavelli L, Yu SH, Scaini R, Darnahal A, Wallace SS, et al.
Maxillary Sinus Elevation Difficulty Score with Lateral Wall Technique.
Int J Oral Maxillofac Implants 2020;35:631-638.

5. Al-Dajani M. Incidence, Risk Factors, and Complications of
Schneiderian Membrane Perforation in Sinus Lift Surgery: A
Meta-Analysis. Implant Dent 2016;25:409-415.

6. d'Elia C, Baldini N, Gabriele G, Nuti N, Juloski J, Gennaro PJJoO.
the Simultaneous sinus lift and implant placement using lateral approach
in atrophic posterior maxilla with residual bone height of 5 mm or less.
A systematic review. 2019;11.

7. Le BT, Borzabadi-Farahani A. Simultaneous implant placement and bone
grafting with particulate mineralized allograft in sites with buccal
wall defects, a three-year follow-up and review of literature. J
Craniomaxillofac Surg 2014;42:552-559.

8. Chaushu G, Vered M, Mardinger O, Nissan J. Histomorphometric analysis
after maxillary sinus floor augmentation using cancellous bone-block
allograft. J Periodontol 2010;81:1147-1152.

9. Molemans B, Cortellini S, Jacobs R, Pinto N, Teughels W, Quirynen M.
Simultaneous sinus floor elevation and implant placement using
leukocyte- and platelet-rich fibrin as a sole graft material. Int J Oral
Maxillofac Implants 2019;34:1195-1201.

10. Turunen T, Peltola J, Yli-Urpo A, Happonen RP. Bioactive glass
granules as a bone adjunctive material in maxillary sinus floor
augmentation. Clin Oral Implants Res 2004;15:135-141.

11. Luongo R, Sgaramella N, Traini T, Bugea C. Graftless Maxillary Sinus
Floor Augmentation with Simultaneous Porcine Bone Layer Insertion: A 1-
to 5-Year Follow-up Study. Int J Oral Maxillofac Implants
2020;35:808-815.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image1/image1}

\end{center}
\end{figure}

Figure-1. Preoperative Panoramic radiograph of a patient with severe
bilateral atrophic posterior maxillary ridge.\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image2/image2}

\end{center}
\end{figure}

Figure-2. Ramus graft fixation in bilateral sinus lift procedure using
bicortical screws\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/image3/image3}

\end{center}
\end{figure}

Figure-3. Post-operative Panoramic radiograph

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