No-prep restorative techniques
No-prep resin-bonded bridges are a well-known option for restoring single-tooth gaps in the anterior region. However, their long-term success remains closely related to proper handling of the material properties, adhesive technique and occlusion. If handled properly, the single-unit, single-retainer cantilever resin-bonded bridge has a definitive role in the treatment of missing front teeth.
To hold the pontic, only a veneer on the palatal side of the adjacent tooth is required (Figures 1–2). The mechanical resistance depends on adhesion to the enamel of the adjacent tooth, and is better when less enamel reduction is required. In short, the less prep done, the more the resistance. No-prep bridges do not weaken the abutment tooth and therefore leave its elastic modulus intact. Regarding materials: the speaker stated that the most frequently used is lithium disilicate, although the use of zirconia is becoming more common.
“The mechanical resistance depends on adhesion to the enamel of the adjacent tooth”
There are a number of clinical situations where resin-bonded all-ceramic cantilever bridges may be properly indicated:
- to replace anterior teeth in children
- cases involving congenitally missing teeth
- cases with retained teeth (such as canines)
- to prevent mesial drifting of molars to the space of a missing tooth by acting as a ‘tilt stopper’
- to replace lower incisors
- immediate cantilever after tooth extraction
- immediate reconstruction after a failed implant
- in patients who have a fear of or aversion to metal
- when price is an issue for the patient
- in patients with aggressive periodontitis
- even in cases involving full mouth rehabilitation
Molar replacement is not recommended with this kind of prosthesis because of mechanical issues. The cantilever would be too distal if used in the posterior region.
It has been observed that mesial contacts of implant crowns which are adjacent to natural teeth tend to open over time (Thilander. 2009; Daftary et al. 2013). With bonded bridges, this did not happen. As the bridge follows the movement of mesial teeth it closes the contact point. The mucosal contact of the pontic can be made to reshape the soft tissue achieving a high pink aesthetic appearance (Figures 3–4).
“The mucosal contact of the pontic can be made to reshape the soft tissue achieving a high pink aesthetic appearance”
The literature shows that single-retainer (cantilever) all-ceramic adhesive bridges perform better than bridges held on two retainers (Kern. 2005; Etemadi et al. 1997), and that single-unit resin-bonded cantilever bridges may perform (clinically) as well as single-unit implants and three-unit bridges with similar OHRQoL results (Lam et al. 2014).
Survival rates over 95% at 5 years and 90% at 10 years have been reported. The two most common complications are fractures and debonding, both of which are easily resolved (Sailer et al. 2013; Botelho et al. 2014; Sasse & Kern. 2014).
“Survival rates over 95% at 5 years and 90% at 10 years have been reported”
The speaker concluded by cautioning that, like most dental procedures, no-prep restorations are technique-sensitive. The rules of material science, adhesive technology and occlusion must be adhered to.