First Upper Molar Replacement Options
For replacing a missing first upper molar in a healthy adult, a dental implant is the definitive treatment of choice, with the specific approach determined by residual bone height: standard implants (≥8mm length) when bone height exceeds 9mm, short implants or transalveolar sinus augmentation when bone height is 5-9mm, and lateral window sinus augmentation when bone height is 3-5mm. 1
Primary Treatment: Dental Implant Restoration
The first upper molar should be replaced with an implant-supported restoration to maintain optimal masticatory function and prevent complications. 1 While first molar occlusion alone provides approximately 90% chewing efficiency, replacement prevents super-eruption of the opposing tooth, which occurs frequently in unopposed posterior teeth (approximately 20% extrude ≥2mm). 2
Treatment Algorithm Based on Residual Bone Height (RBH)
The height of subantral bone is the primary determinant of surgical approach: 1
When RBH > 9mm:
- Place a standard implant (length ≥8mm) or short implant (length <8mm) without bone augmentation 1
- This is the most straightforward approach with minimal surgical complexity 1
- Maintain at least 1mm of bone apical to the implant fixture 1
When RBH is 5-9mm:
- Two options exist: transalveolar maxillary sinus floor augmentation (MSFA) with simultaneous standard implant placement, OR short implant placement without augmentation 1
- Transalveolar MSFA is less invasive than lateral window approach but offers limited visibility 1
- Short implants avoid augmentation entirely but require favorable crown-to-implant ratio 1
When RBH is 3-5mm:
- Perform lateral window MSFA with simultaneous implant placement 1
- This provides increased visibility compared to transalveolar approach 1
- More invasive and technically demanding, with higher complication rates 1
When RBH ≤3mm:
- Perform lateral window MSFA with delayed implant placement 1
- Alternative options include tilted implants or distal cantilevers, though these have limited long-term evidence 1
Alternative Treatment Options
Fixed Dental Prosthesis (Bridge)
If adjacent teeth require crowns or have existing restorations, a traditional fixed bridge may be considered. However, this requires preparation of healthy adjacent teeth and does not prevent bone resorption. 1
Removable Partial Denture
This is the least favorable option for a single missing molar, as it provides inferior function, requires removal for cleaning, and does not prevent bone loss. 3
No Replacement
In select cases where the patient perceives no chewing deficiency and accepts the aesthetic gap, monitoring without replacement is acceptable. 2 However, this requires vigilant monitoring for super-eruption of the opposing tooth, which can complicate future restorative treatment. 2
Critical Considerations for Implant Placement
Timing of Implant Placement Post-Extraction
If the first molar was recently extracted, timing matters significantly for anterior teeth but is less critical for molars: 1
- Early implant placement (4-8 weeks post-extraction) allows soft tissue healing and is ideal for multi-rooted teeth like first molars 1
- Early placement with partial bone healing (12-16 weeks) is indicated when extended peri-apical lesions prevent proper 3D implant positioning 1
- Socket grafting at extraction is strongly recommended to preserve ridge dimensions and avoid complex augmentation procedures later 1
Implant Diameter Selection
For molar replacement with adequate bone width, use regular diameter implants (>3.7mm) or wide diameter implants as the gold standard. 4 Narrow diameter implants (<3.5mm) should only be considered when moderate horizontal bone resorption prevents placement of regular diameter implants and the patient refuses lateral bone augmentation. 4
Common Pitfalls to Avoid
Do not place immediate implants (Type 1) in posterior maxilla unless you are a highly experienced surgeon with ideal anatomical conditions (intact facial bone wall >1mm, thick gingival biotype, no infection). 1 This complex procedure is rarely indicated for first molars.
Do not underestimate sinus proximity. Always obtain CBCT imaging to accurately measure residual bone height before planning implant placement in the posterior maxilla. 1
Do not ignore crown-to-implant ratio when selecting short implants, as unfavorable ratios increase prosthetic complications. 1
Do not use antibiotics without surgical intervention if infection is present—proper drainage and source control are mandatory. 5
Long-Term Prognosis
Implant-supported prostheses in the posterior maxilla demonstrate excellent long-term survival rates (>99% at 20 years) when proper protocols are followed. 6 The treatment provides predictable restoration of function with minimal complications when appropriate patient selection and surgical technique are employed. 1, 6