Evaluation of anatomical considerations in the posterior maxillae for sinus augmentation

Histological, radiological, and clinical outcomes of sinus floor elevation using a lateral approach for pre-/post-extraction of the severely compromised maxillary molars: a study protocol for a randomized controlled trial

BACKGROUND

The volume of residual alveolar bone is critical to the survival of dental implants. When the volume of alveolar bone in the posterior maxillary region is less than 4 mm, maxillary sinus floor elevation (MSFE) with the lateral approach is an effective option. Traditionally, this standard approach is usually conducted at 4-6 months after tooth extraction (standard MSFE). However, defective dentition due to extraction can impair mastication during the period of bone remodeling, especially if the molars on both sides are severely compromised and must be extracted. MSFE before extraction (modified MSFE) can take full advantage of residual tooth strength. However, the effectiveness and practicability of the modified MSFE procedure remain unknown. Therefore, the aim of this study was to compare the clinical outcomes of modified vs. standard MSFE, in order to provide references to periodontists.

METHODS/DESIGN

The study cohort included 25 adult patients (50 surgery sites) recruited from Peking University Hospital and School of Stomatology who met the inclusion criteria. The two sides of each patient will be randomly divided into two groups: a test group-modified MSFE or a control group-standard MSFE. The surgical duration and patient-reported outcomes (visual analog scale for discomfort) will be documented. Clinical indicators, including implant survival rates, mucosal conditions, and complications, will be recorded every 6 months during the 5-year follow-up period. The volume of the alveolar bone and marginal bone level will be assessed radiographically (cone-beam CT and periapical films) every 6 months. Histological analysis of biopsy samples retrieved from both sides will be performed to evaluate the biological features of the bone.

DISCUSSION

The current study will explore the implant survival rates, safety, reliability, effectiveness, and practicability of the modified MSFE procedure. Moreover, the extent of osteogenesis on the sinus floor will also be assessed. The results of this trial will provide strategies for the modified MSFE procedure to achieve ideal clinical outcomes.

TRIAL REGISTRATION

International Clinical Trials Registry Platform ChiCTR1900020648 . Registered on 1 January 2019.

Effect of bone quality and quantity on the primary stability of dental implants in a simulated bicortical placement

OBJECTIVES

Conventional dental implants inserted in the molar region of the maxilla will reach into the sinus maxillaris when alveolar ridge height is limited. When surgery is performed without prior augmentation of the sinus floor, primary stability of the implant is important for successful osseointegration. This study aimed at identifying the impact of bone quality and quantity at the implantation site on primary implant stability of a simulated bicortical placement.

MATERIALS AND METHODS

In our in vitro measurements, bone mineral density, total bone thickness and overall cortical bone thickness were assessed by micro-computed tomography (μCT) of pig scapulae, which resembled well the bicortical situation found in human patients. Dental implants were inserted, and micromotion between bone and implant was measured while loading the implant with an axial torque.

RESULTS

The main findings were that primary implant stability did not depend on total bone thickness but tended to increase with either increasing bone mineral density or overall cortical bone thickness.

CLINICAL RELEVANCE

Limited bone height in the maxilla is a major problem when planning dental implants. To overcome this problem, several approaches, e.g. external or internal sinus floor elevation, have been established. When planning the insertion of a dental implant an important aspect is the primary stability which can be expected. With other factors, the dimensions of the cortical bone might be relevant in this context. It would, therefore, be helpful to define the minimum thickness of cortical bone required to achieve sufficient primary stability, thus avoiding additional surgical intervention.

Retrospective study of maxillary sinus dimensions and pneumatization in adult patients with an anterior open bite

INTRODUCTION

The aim of this study was to evaluate differences in the maxillary sinus floor levels between adults with an anterior open bite and those without.

METHODS

This retrospective study included 30 subjects: 15 adults with an anterior open bite (mean age, 21.5 ± 4.3 years) and 15 control subjects with normal occlusion (mean age, 21.7 ± 3.1 years). Cone-beam computed tomography and lateral cephalograms were analyzed before treatment.

RESULTS

The open-bite group exhibited a significantly greater maxillary posterior alveolar height (P <0.05). The craniocaudal heights of the maxillary sinus in the region between the first and second molars and between the second premolar and first molar were significantly greater in the open bite group (40.5 and 39.0 mm, respectively) than in the control group (36.7 and 34.7 mm, respectively; P <0.05 for both). The basal bone heights in the regions between the first and second molars, the second premolar and first molar, and the first and second premolars were significantly smaller in the open-bite group than in the control group (P <0.001 for all).

CONCLUSIONS

Vertical pneumatization of the maxillary sinus floor in the region between the first and second molars and between the second premolar and first molar is greater in adults with an anterior open bite than in those without, whereas basal bone height in the maxillary posterior region is lower in the open-bite patients.

Dental pulp stem cells as a multifaceted tool for bioengineering and the regeneration of craniomaxillofacial tissues

Dental pulp stem cells, or DPSC, are neural crest-derived cells with an outstanding capacity to differentiate along multiple cell lineages of interest for cell therapy. In particular, highly efficient osteo/dentinogenic differentiation of DPSC can be achieved using simple in vitro protocols, making these cells a very attractive and promising tool for the future treatment of dental and periodontal diseases. Among craniomaxillofacial organs, the tooth and salivary gland are two such cases in which complete regeneration by tissue engineering using DPSC appears to be possible, as research over the last decade has made substantial progress in experimental models of partial or total regeneration of both organs, by cell recombination technology. Moreover, DPSC seem to be a particularly good choice for the regeneration of nerve tissues, including injured or transected cranial nerves. In this context, the oral cavity appears to be an excellent testing ground for new regenerative therapies using DPSC. However, many issues and challenges need yet to be addressed before these cells can be employed in clinical therapy. In this review, we point out some important aspects on the biology of DPSC with regard to their use for the reconstruction of different craniomaxillofacial tissues and organs, with special emphasis on cranial bones, nerves, teeth, and salivary glands. We suggest new ideas and strategies to fully exploit the capacities of DPSC for bioengineering of the aforementioned tissues.