A Technique Combining Straumann Zygomatic and BLX Implants for full arch rehabilitation PART 1
The consideration of Zygoma implants is typically thought to be reserved only for severe bone atrophy from long-term edentulism and denture wearing. However, bone atrophy is not the only contributor to a lack of bone. Other osseo-destructive mechanisms include odontogenic pathology, sinus anatomy, and pneumatization following extraction, as well as iatrogenic factors (failed prior treatments), and may well be present in dentate individuals with terminal or dysfunctional dentitions.
In such patients, early planning and treatment, which may include Zygomatic implants, before they face full edentulism can be highly advantageous not only through halting the progression of odontogenic diseases and its associated additional surgical constraints, but also in a patient’s journey and physical, mental and social wellbeing. Early treatment offers additional means of controlling the outcome both surgical and restorative, as well as a significant improvement in the patient experience and quality of life.
Traditionally the advanced nature of Zygomatic implants and suspected complications historically reported in the literature have led to a reluctance by clinicians to use this method before other alternatives have been all but exhausted.
However, when anatomical, biological, pathological, occlusal, or other constraints exist, which strain traditional implant treatment to the limits of its bioadaptive capacity, a new technique with Zygomatic implants may offer a more definitive alternative by working well within its limitations and a better controlled biomechanical equilibrium.
The following case report describes the new Straumann Zygomatic implant ZAGA flat used in combination with Straumann BLX implants for the successful immediate rehabilitation of a partially dentate patient who has worn partial dentures for many years and suffered from the consequences of partial dentures and significant oral dysfunction. The case report describes the rationale and the procedures leading to the fitting of final fixed implant-supported restorations within 24 hours from the surgery.
The patient was 61 years old female, non-smoker, diabetic (Type 2) on Metformin - well controlled, has mild osteoporosis, takes Vitamin D, mildly overweight (BMI 34.2) and has no other relevant systemic conditions.
The suffered cycles of failed dental work and tooth loss predominantly from decalcification and recurrent caries. She was referred by her dentist for bimaxillary implant-supported rehabilitation after exploring her options and considering her desires for a more definitive solution, functioning teeth and a ‘nice smile’.
On presentation she had many missing teeth and carried upper and lower partial dentures, which she had for 30 years but has not been able to wear at all since the loss of tooth 34 shortly prior to her presentation, which served as the last remaining natural occlusal stop. She had severe oral dysfunction and was unable to bite or chew numerous foods. She was embarrassed to smile. (Fig. 1)
Oral hygiene was poor, and the remaining natural teeth had mild periodontitis with generalized horizontal bone loss (20% in the upper and 40% in the lower). The teeth were structurally compromised from large restorations and recurrent caries, and some were affected by drifting and/or supraeruption. The skeletal bases were in a Class 2 Div 2 correlation, and there was a gross collapse of the Occlusal Vertical Dimension with no stop by any natural teeth. (Fig. 2, 3, 4)
Rationale for Zygomatic Implants
For the purpose of this article the presentation will focus on the upper arch. The option to preserve the patient’s remaining upper teeth was considered but excluded due to the guarded-to-poor prognosis of those teeth, and importantly also due to the limitations/constraints of such option and obstacles to achieving the desired outcome in terms of dental and gingival aesthetics, function, hygiene, and longevity.
The removal of all the remaining upper natural teeth was preferred by both the patient and the referring dentist.
Rehabilitation with full fixed implant-supported restorations provides an opportunity to better control the outcome and an improved flexibility in the planning and design process in order to reach the functional and aesthetic expectations of the patient, as well as to facilitate improved hygiene.
Before relying on the radiographic images to plan implant positions, it was critical to assess the clinical situation and gum display. On smiling there was a moderate gum display in the upper (including in the edentulous segment), and tooth (but no gum) display in the lower. This was an important consideration in planning her treatment, and dictated a need for a moderate alveolectomy.
Radiographic Assessment of Zygomatic Bone and Sinus Condition
(Fig. 5) Below there is a panoramic reconstruction of a 3-D Cone Beam CT file with the re-slice curve following the maxillary arch anteriorly and diverging laterally to capture the Zygomatic bone. This allow assessment of the maxillary bone and sinuses along the path of the planned Zygoma implants, as well as the shape and thickness of the Zygomatic bone itself (Fig. 6).
The left sinus (Fig. 5) is normal, but on the right there is thickening of the sinus mucosa. This thickening may be related to past odontogenic pathology but is inconsequential as there otherwise appears to be normal drainage and a patent opening of the osteo-meatal complex.
The thickness and cross-sectional shape of the Zygomatic bone in (Fig. 6) is not ideal and an implant with a smaller apex and thinner core, like Straumann Zygomatic Implant ZAGA Flat, has a particular advantage in such cases.
Taking the required alveolectomy into account, the volume of maxillary bone was borderline but adequate for four implants from 5 to 5 (angulated in the posterior). Whilst this would typically provide adequate mechanical support for fixed teeth, the radiographic bone quality was Type 3-4, which would later be confirmed at surgery. The poor quality of the bone would affect the stability of standard implants, thus Zygomatic implants was considered as a more predictable alternative, subject to further intra-operative assessment.
Digital Smile Design
Due to the absence of a natural occlusal stop it was important to establish and register the correct Occlusal Vertical Dimension in order for the laboratory to subsequently correlate the occlusion to the real life situation. This was achieved by construction an occlusal stop using composite material and bite registration using Coltene Jet Bite.
Using digitized pre-operative models and bite registration of the patients dentition the laboratory superimposed the digital smile design using full face photographs and digitally planned the ideal set up of teeth on planning software taking into account the patient’s aesthetic desires and open bite position.
The patient was provided with prescriptions according to the medication schedule ordinary used at our clinic.
The patient was treated under a General Anesthetic (TIVA) with a combination of propofol, midazolam, and remifentanil. Patients recover quickly using this technique, which is important for the subsequent try-in stage, which requires cooperation.
Dexamethasone 8mg, Cefazolin, IV Paracetamol