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A Fine Place To Start by Dr. LeRoy Horton

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Categories: Implant Dentistry;
Dentaltown Magazine 

With its anatomical and aesthetic disposition, the mandibular first premolar is a good site to practice immediate implant placement

by Dr. LeRoy Horton

In my years teaching implants to doctors, I have observed that most programs—including my own—start the hands-on process with posterior edentulous sites. This is because they present with the least possible technical difficulty to the practitioner; hence, they are a great way to introduce a beginner to hands-on surgical experience.

Once enough repetitions are performed and comfort is achieved with the basic principles of implant surgery, the natural progression is immediate implant placement. When done correctly, the success rates are equal to implants placed in edentulous sites, yet shave several months off the entire process.1

I have found that the best tooth for this learning is the mandibular first premolar:
  • Molars (upper and lower) can often be difficult to remove, let alone in a way that preserves bone, and creating an osteotomy in the midst of two to three empty sockets can be a challenge.

  • Anterior teeth present with high aesthetic demands as well as anatomical challenges, because they are often positioned on the very facial of the alveolar process.

  • Upper premolars also tend to be in such a position within the bone and this adds a degree of difficulty to creating the osteotomy in the correct position.
The mandibular premolar arguably presents with the easiest anatomical and aesthetic disposition. This case will primarily demonstrate the step-by-step process from extraction to implant placement and discuss the evidence-based principles at each step. Secondarily, I make the practice-based argument that the mandibular first premolar extraction site can be the most ideal site for clinicians to begin their immediate implant practice.

We will be exploring a case in which tooth #28 has fractured to the gum line (Figs. 1a and 1b) and implant therapy was the chosen course of treatment.
Dental Implant Placement
Fig. 1a
Dental Implant Placement
Fig. 1b


Checklist and diagnostics
Upon initial examination, I like to go through my basic checklist:
  • Medical history/medications: no contraindications.

  • Oral health: multiple edentulous areas, mild periodontal inflammation (patient already had scaling and root planning performed), no pending emergencies/infections, several restorative needs.

  • General occlusion: missing molars; canine-to-canine occlusion suggests Class I relationships.

  • Anterior occlusion: mild wear, 1mm overjet, 2mm overbite.

  • Biotype: medium thickness.

  • Aesthetic demand: minimal.

  • Goal: to remove the remaining root and place an immediate implant.
This basic checklist is a preliminary one; it is not meant to plan the entire case but serves as a filter that tells me whether this is going to be a relatively simple case (as this is) or a more complex one that will require some time set aside for further planning (diagnostic models and wax-ups).

A cone beam image was taken to assess several anatomical factors.

We can see from Figs. 2a–2c why this is such a favorable case for a young implantologist to foray into immediate implant placement: Tooth #28 is almost centered in the alveolar bone, with a thick lingual cortical plate and a thinner but intact facial plate. This root, as most lower premolars are, is a singular conical root of average length.2
Dental Implant Placement
Fig. 2a
Dental Implant Placement
Fig. 2b
Dental Implant Placement
Fig. 2c


The angulation of the mandible in this cross section appears very straight and vertical, with a healthy appearance of trabecular bone between the cortices. The very straight nature of the bone means there are fewer angles to accommodate when drilling the osteotomy. The socket will provide a great reference point for initial drilling angle in the coronal plane from superior to inferior, and the practitioner will mainly have to focus on just the sagittal angulation from mesial to distal. In other words, all you have to do is drill straight down.

The inferior alveolar nerve was traced on the viewing software and it exits the mental foramen directly under Tooth #29 about 9mm inferior to its apex and 4mm distal to the area below the planned #28 implant site. This is a common spatial orientation of the foramen, making the mandibular first premolar a more technically safe implant site than the second premolar.3

To recap key points:
  • Ease of extraction: Conical roots of lower premolars are most often dislodged with simple elevation or rotational forces using standard or pediatric size 151 forceps.

  • Safe distance from vital anatomy: In the mandible, the inferior alveolar nerve usually exits out of the mental foramen closer to the second premolar, not the first.

  • 90-degree vertical alveolus: The fewer angles the clinician has to accommodate in the surgery, the less complicated it will be.
Beginning the surgery with PRF
For dentists using autologous platelet products (Figs. 3a–3c), the best time to start your blood draw is right after numbing. There are a lot of different spin protocols available these days, depending on the type of final product you are looking for. It must be remembered that the speed of the spin is a factor of the design of your particular centrifuge so we cannot be too attached to one particular number when it comes to RPMs; we should instead be more focused in the amount of G-force generated by the RPMs. This is dictated by the size of the rotor assembly, the pitch of the tube holder, etc.
Dental Implant Placement
Fig. 3a
Dental Implant Placement
Fig. 3b
Dental Implant Placement
Fig. 3c


In general, for standard platelet-rich fibrin (PRF) membrane, 200G’s has become the minimal relative force needed to create a solid enough membrane without damaging the platelets by over-spinning and to retain more white blood cells, which will help modulate the inflammation process in your surgery site.4

Evidence has shown that adding platelet products will make the allograft easier to handle, because the plasma is viscous and can be made to solidify, creating what is known as “sticky bone.” Not only can this make your surgery easier, but also it adds almost 20 times the amount of platelets that will release growth factors critical to healing, compared with a natural blood clot. The fibrin matrix helps keep these growth factors in place longer, all assisting the healing process, in particular vascularization.4,5

Chart 1 illustrates the flow chart for surgery when incorporating platelet products.
A Fine Place To Start

 Extraction
The extraction with lower premolars is usually very simple. If there is enough tooth structure above the bone, take a 15 blade scalpel and gently do a sulcular incision to separate any attachment in the sulcus to the tooth structure. Then, using a standard or smaller-size 151 forceps in rotational motions, these very conical teeth will come out very easily. I prefer a smaller or pediatric-size forceps so that the beaks don’t inadvertently pressure or damage the neighboring teeth because rotational movements may impede on the space of the neighboring teeth. In this case, however, the tooth structure on the lingual is broken to the bone level (Figs. 4a and 4b), not allowing for a point of purchase by the forceps without removing bone.
Dental Implant Placement
Fig. 4a
Dental Implant Placement
Fig. 4b


Because this is the type of case where there isn’t much tooth to grab onto, and compromised neighboring teeth, I recommend laying a conservative buccal flap and removing interproximal bone on one side using a surgical 557 bur, without extending beyond the buccal and lingual plates. This will allow you to get a small elevator into the trough and elevate against bone only, without inadvertently putting pressure on other teeth. The aforementioned conical nature is favorable to elevating forces. Refer to the cone-beam section pictured earlier and you can see why within 10 seconds, this particular tooth was out of the socket (Fig. 5). Bone removed without damaging the buccal and lingual plate will simply fill in with the natural healing process without compromising the vertical dimension, and in the case of immediate implant will be aided by the bone graft material used.6

Dental Implant Placement
Fig. 5
Placing the implant
The implant placement at this point, given the aforementioned favorabilities, is easy. You will start your osteotomy with the drill laterally pressed against the lingual plate within the socket (Fig. 6). This will keep your implant positioned centrally within the alveolar process apically and as far as allowable from the thin buccal plate crestally, to allow for allograft to be placed in that subsequent gap.

Dental Implant Placement
Fig. 6

I recommend underpreparing the osteotomy by one size to ensure that primary stability is achieved. Because only the apical third or so of the implant will be engaging the bone, you can avoid having your planned implant size freely spinning with no retention.

If you’re not placing an immediate provisional or healing collar, you want to achieve at least 20Ncm of torque, but more will ensure that the implant will stay stable even only with that apical engagement. As you are packing the allograft and potentially putting forces on the implant, you do not want it easily displaced.

If you will be placing a provisional or a healing collar, aim for 35–50Ncm. Over the first few weeks, as the bone is remodeling, there will be a loss of up to 60% of the implant mechanical stability, so a low initial torque could lead to early failure due to micromovement from masticatory forces.7,8 We want to make sure that in this period there is enough residual retention left to withstand these forces until the bone remodels to a stronger biologic connection to the implant.

In fact, if you are in trabecular bone, you can prepare the osteotomy just enough to fit the apex of the implant into it. Then use quite a bit of force to tighten it down, as studies show you can go upwards of 170Ncm with no detriment so long as you are safely with in medullary bone. In comparison to cortical bone, medullary bone is much more vascular and able to remodel in response to compression.9

In Figs. 7a–7d, you can see that the tooth was removed and the implant inserted to approximately 3mm below the estimated gingival margin. This will help maintain as much of the papilla as possible in the interproximal of either side.10
Dental Implant Placement
Fig. 7a
Dental Implant Placement
Fig. 7b
Dental Implant Placement
Fig. 7c
Dental Implant Placement
Fig. 7d


Allograft was placed along the buccal gap and the mesial where the extraction trough was made. The graft was placed not only in the gap but also above the bone on the buccal, to add volume to the soft tissue as it heals.11,12 Then a piece of PRF membrane was placed over the implant and a healing cap placed through it, creating a poncho effect. The fibrin membrane is thus held in place by the healing collar and covers the entire socket further, helping keep the graft in place. Sutures are then positioned using a mattress technique to firmly affix the gingiva against the collar.

Because infection is always of some concern, adding PRF/PRP to the graft and surgery site provides an added level of protection, as well as improved soft and hard-tissue healing.13 There are many differing opinions on antibiotic protocols, ranging from none to just a prophylactic dose, as well as perioperative protocols. This decision is case-dependent and multifactorial; no single recommendation would be the right one for every single patient.14

Postoperative return
A postoperative cone beam image was taken to confirm the placement, with an intraoral photograph about 10 days later. Figs. 8a–8c show the implant was placed as planned, with minimal angular complications given the straight nature of the bone. The soft tissue on the buccal is pink and firm with visible thickness.
Dental Implant Placement
Fig. 8a
Dental Implant Placement
Fig. 8b
Dental Implant Placement
Fig. 8c


Conclusion
Immediate implants are a viable part of a thriving implant practice, especially in American culture, which values expediency. The viability comes in the success rates achieved when performed correctly by the practitioner. Given that all doctors must progress from beginner to expert, I hope I have provided some good strategies for success, as well as made the case that the mandibular first premolar is a great starting point for doctors to expand their skill set.
Earn CE credit and learn about
immediate anterior implants

Dr. LeRoy Horton’s CE course takes readers through a step-by-step process of
performing an immediate implant placement in the anterior maxilla, with
discussion of principles that will aid in surgical, restorative and aesthetic success.
To get started, click here.


References
1. Ribeiro FS, Pontes AE, Marcantonio E, Piattelli A, Neto RJ, Marcantonio E Jr. Success rate of immediate nonfunctional loaded single-tooth implants: immediate versus delayed implantation. Implant Dent. 2008 Mar;17(1):109-17. doi: 10.1097/ID.0b013e318166cb84. PMID: 18332764.
2. Blaine M. Cleghorn, William H. Christie, Cecilia C.S. Dong. The root and root canal morphology of the human mandibular second premolar: A Literature Review, Journal of Endodontics, Volume 33, Issue 9, 2007, Pages 1031-1037
3. Pyun JH, Lim YJ, Kim MJ, Ahn SJ, Kim J. Position of the mental foramen on panoramic radiographs and its relation to the horizontal course of the mandibular canal: a computed tomographic analysis. Clin Oral Implants Res. 2013 Aug;24(8):890-5. doi: 10.1111/j.1600- 0501.2011.02400.x. Epub 2012 Jan 6. PMID: 22220715.
4. Dohan Ehrenfest DB, Del Corso M, Diss A, Mouhry J, Charrier JB. Three dimensional architecture and cell composition of a Choukroun’s platelet-rich fibrin clot and membrane. J Periodontol. 2010;81(4):546-55
5. Shahram Ghanaati, MD, DMD, PhD; Carlos Herrera-Vizcaino, DDS; Sarah Al-Maawi, DMD; Jonas Lorenz, DMD; Richard J Miron, DDS; Katja Nelson, DMD, PhD; Frank Schwarz, DMD, PhD; Joseph Choukroun, MD; Robert Sader, MD, DMD, PhD. Fifteen years of platelet rich fibrin in dentistry and oral-maxillofacial surgery: How high is the level of scientific evidence? J Oral Implantol (2018) 44 (6): 471–492.
6. Grunder U, Gracis S, Capelli M. Influence of the 3-D bone-to-implantrelationship on esthetics. Int J Periodontics Restorative Dent 2005;25:113–119. 7. Baldi D, Lombardi T, Colombo J, et al. Correlation between insertion torque and implant stability quotient in tapered implants with knife edge thread design. Biomed Res Int 2018;2018:7201093.
8. Szmukler-Moncler S, Piattelli A, Favero GA, Dubruille JH. Considerations preliminary to the application of early and immediate loading protocols in dental implantology. Clin Oral Implants Res. 2000;11:12–25
9. Berardini M, Trisi P, Sinjari B, Rutjes AW, Caputi S. The effects of high insertion torque versus low insertion torque on marginal bone resorption and implant failure rates: A systematic review with meta-analyses. Implant Dent. 2016 Aug;25(4):532-40.
10. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of the bone on the presence or absence of the interproximal dental papilla. J Periodontol. 1992 63:995-996
11. Chu S, Salama M, Salam H, Garber D et al. The dual-zone therapeutic concept of managing immediate implant placement and provisional restoration in the anterior extraction sockets. Compendium of Cont Dent Ed. 2012 33;
12. Tarnow DP, Chu SJ, Salama M, Stappert C. Flapless post-extraction socket implant placement in the esthetic zone: Part 1. The effect of bone grafting and/or provisional restoration of facial-palatal ridge dimensional change – a retrospective cohort study. Int J Perio and Rest Dent 2014, 34(3):323-31
13. Hoaglin DR, Lines GK. Prevention of localized osteitis in mandibular third-molar sites using platelet-rich fibrin. Int J Dent 2013;2013:875380
14. Surapaneni H et al. Antibiotics in dental implants: A review of literature. J Pharm Bioallied Sci. 2016 Oct;8(Suppl 1): 28-31

Author Bio
LeroyHorton Dr. LeRoy Horton completed his bachelor’s degree in biology from Pacific Lutheran University in Washington state in 2003, then earned his DDS degree from the University of Washington School of Dentistry in 2007. Having always been fascinated with dental implants, Horton pursued advanced training over the years, attaining fellowships and completing master’s courses. Eventually he earned his board certification as a diplomate of the International Congress of Oral Implantologists. He currently owns two practices in the greater Seattle area and serves our profession as a nationally recognized AGD instructor

 

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