Hi, this is Steve and thank you for your question...if possible, can you send a picture of the base of the pear tree trunk where it enters the soil? Thanks. 

From the picture, I would rule out insects or diseases as when we see dying/dead branches from the top down it normally is a root issue. Looking at the picture where the trunk meets the soil, it appears the tree was planted too deeply as there is no root flare. This can cause circling/girdling roots which can cause injury to the tree as many as a dozen or more years after planting by cutting off the flow of nutrients and water to the crown of the tree. A homeowner can attempt to correct this issue. Circling/girdling roots may be several inches below ground. Circling roots not embedded into the trunk should be cut and removed. For girdling roots putting pressure on the trunk, cut and remove the root without causing injury to the trunk. The tree will likely recover without any long-term effects. When girdling roots are embedded into the trunk, cut the root without causing injury to the trunk, if possible. However, do not remove the girdling root section if it is embedded into the trunk, as this opens the trunk to decay and the trunk will be structurally weak. The tree may or may not survive; only time will tell. Information from Florida, with visuals, is included in this link: https://hort.ifas.ufl.edu/woody/remove-girdling-roots.shtml

I would also suggest the dead branches be pruned out when possible. Also, from the picture, it appears the lawn is growing up to the trunk, if so, we recommend removing the lawn in a large circle and replacing with an organic mulch, such as wood chips. If these steps are more than you wish to tackle, you can search for a certified arborist in your area by going to https://www.treesaregood.org/findanarborist Again, thank you for your question and don’t hesitate to contact us with further questions on this or any landscape question, Steve.